add LST

G4:G431/CORDIC/Makefile

@@ -0,0 +1,13 @@
+BINARY      := cordic
+PREFIX      := /usr/bin/arm-none-eabi
+CFLAGS       = -std=c23
+CPPFLAGS     = -std=c++11
+# MCU code
+MCU         := G431xx
+# change this linking script depending on particular MCU model,
+LDSCRIPT    := stm32g431xb.ld
+LDLIBS      += -lm
+
+include ../makefile.g4
+include ../../makefile.stm32
+

G4:G431/CORDIC/astro.c

@@ -0,0 +1,204 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <math.h>
+#include <stdint.h>
+
+#include "astro.h"
+#include "cordic.h"
+
+static int sincosflag = 0; // math.h
+// longitude/latitude + in rad/hrs
+//static float longitude = 41.44143375f, latitude = 43.6535278f;
+static float lat_rad = 43.6535278f * M_PIf / 180.f;
+static float long_hrs = 41.44143375f / 15.f;
+
+static void sincosf_m(float angle, float *s, float *c){
+    if(s) *s = sin(angle);
+    if(c) *c = cos(angle);
+}
+
+static void (*sincosf)(float, float*, float*) = sincosf_m;
+
+void set_sincos(int iscordic){
+    if(iscordic) sincosf = cordic_sincos;
+    else sincosf = sincosf_m;
+    sincosflag = iscordic;
+}
+
+int get_sincos(){ return sincosflag; }
+
+/* Helper functions for angle normalization (single precision) */
+static float normalize_degrees(float angle){
+    angle = fmodf(angle, 360.0f);
+    if (angle < 0.0f) angle += 360.0f;
+    return angle;
+}
+
+static float normalize_hours(float hours){
+    hours = fmodf(hours, 24.0f);
+    if (hours < 0.0f) hours += 24.0f;
+    return hours;
+}
+
+/* 1. Compute Modified Julian Date from UNIX time (seconds since 1970-01-01 00:00:00 UTC) */
+float MJD_from_unix(uint32_t t){
+    return 40587.f + (float)t / 86400.0f;
+}
+
+float LST_from_unix(uint32_t t){
+    uint32_t days = t / 86400;
+    uint32_t sec  = t % 86400;
+
+    float mjd_int = 40587.0f + (float)days;
+
+    float T = (mjd_int - 51544.5f) / 36525.0f, T2 = T*T, T3 = T2*T;
+    float gmst0_sec = 24110.54841f + 8640184.812866f*T + 0.093104f*T2 - 6.2e-6f*T3;
+    float ut1_sec = (float)sec * 1.00273790935f;
+    float gmst_sec = gmst0_sec + ut1_sec;
+    float lst_hours = gmst_sec / 3600.0f + long_hrs;
+    return normalize_hours(lst_hours);
+}
+
+/* 3. Convert Hour Angle (HA) to Right Ascension (RA) and vice versa.
+   All angles in degrees. LST is Local Sidereal Time in degrees. */
+float ha_to_ra(float ha, float lst){
+    float ra = lst - ha;
+    return normalize_degrees(ra);
+}
+
+float ra_to_ha(float ra, float lst){
+    float ha = lst - ra;
+    // Hour angle is usually in range [-180,180)
+    ha = normalize_degrees(ha);
+    if (ha > 180.0f) ha -= 360.0f;
+    return ha;
+}
+
+/* 4. Convert Altitude-Azimuth coordinates to Equatorial (Hour Angle, Declination)
+   and back. All angles in degrees. Azimuth is measured from North through East. */
+void altaz_to_hadec(float alt_deg, float az_deg, float *ha_deg, float *dec_deg){
+    float alt = alt_deg * M_PIf / 180.0f;
+    float az  = az_deg  * M_PIf / 180.0f;
+
+    float sin_alt, cos_alt, sin_az, cos_az, sin_lat, cos_lat;
+    sincosf(alt, &sin_alt, &cos_alt);
+    sincosf(az,  &sin_az,  &cos_az);
+    sincosf(lat_rad, &sin_lat, &cos_lat);
+
+    /* Declination */
+    float sin_dec = sin_alt * sin_lat + cos_alt * cos_lat * cos_az;
+    float dec = asinf(sin_dec);
+
+    /* Hour angle (using atan2f for sign determination) */
+    float x = sin_alt * cos_lat - cos_alt * sin_lat * cos_az;
+    float y = -cos_alt * sin_az;
+    float ha = atan2f(y, x);   // radians
+
+    *ha_deg  = ha * 180.0f / M_PIf;
+    *dec_deg = dec * 180.0f / M_PIf;
+}
+
+void hadec_to_altaz(float ha_deg, float dec_deg, float *alt_deg, float *az_deg){
+    float ha  = ha_deg  * M_PIf / 180.0f;
+    float dec = dec_deg * M_PIf / 180.0f;
+
+    float sin_dec, cos_dec, sin_ha, cos_ha, sin_lat, cos_lat;
+    sincosf(dec, &sin_dec, &cos_dec);
+    sincosf(ha,  &sin_ha,  &cos_ha);
+    sincosf(lat_rad, &sin_lat, &cos_lat);
+
+    /* Altitude */
+    float sin_alt = sin_lat * sin_dec + cos_lat * cos_dec * cos_ha;
+    float alt = asinf(sin_alt);
+
+    /* Azimuth (from North through East) */
+    float x = sin_dec * cos_lat - cos_dec * sin_lat * cos_ha;
+    float y = -cos_dec * sin_ha;
+    float az = atan2f(y, x);   // radians, [-π, π]
+
+    *alt_deg = alt * 180.0f / M_PIf;
+    *az_deg  = az * 180.0f / M_PIf;
+    if (*az_deg < 0.0f) *az_deg += 360.0f;
+}
+
+/**
+ * @brief Calculate refraction constants A and B for the model dZ = A*tan(Z) + B*tan^3(Z)
+ *
+ * This is a single-precision adaptation of the SOFA iauRefco / ERFA eraRefco function.
+ * Optimized for microcontrollers without hardware double-precision support (e.g., STM32G431).
+ *
+ * @param phpa    Pressure at the observer (hPa = mbar)
+ * @param tc      Ambient temperature at the observer (degrees C)
+ * @param rh      Relative humidity at the observer (range 0-1)
+ * @param wl      Wavelength (micrometers). Use 0.55 for optical, >100 for radio.
+ * @param refa    Output: tan(Z) coefficient (radians)
+ * @param refb    Output: tan^3(Z) coefficient (radians)
+ */
+static void refco_f32(float phpa, float tc, float rh, float wl, float *refa, float *refb) {
+    // Restrict input parameters to safe values (clamp)
+    float t = tc;
+    if(t < -150.0f) t = -150.0f;
+    if(t > 200.0f)  t = 200.0f;
+
+    float p = phpa;
+    if(p < 0.0f)     p = 0.0f;
+    if(p > 10000.0f) p = 10000.0f;
+
+    float r = rh;
+    if(r < 0.0f)    r = 0.0f;
+    if(r > 1.0f)    r = 1.0f;
+
+    float w = wl;
+    if(w < 0.1f)  w = 0.1f;
+    if(w > 10.0f) w = 10.0f;
+
+    // Water vapour pressure at the observer
+    float pw = 0.0f;
+    if(p > 0.0f){
+        // Saturation vapour pressure (empirical formula)
+        float ps = powf(10.0f, (0.7859f + 0.03477f * t) / (1.0f + 0.00412f * t))
+                   * (1.0f + p * (4.5e-6f + 6e-10f * t * t));
+        pw = r * ps / (1.0f - (1.0f - r) * ps / p);
+    }
+
+    // Temperature in Kelvin
+    float tk = t + 273.15f;
+
+    // Refractive index minus 1 at the observer (gamma = (n - 1) at the observer)
+    float gamma;
+    // Optical/IR: wavelength-dependent formula
+    float wlsq = w * w;
+    gamma = ((77.53484e-6f + (4.39108e-7f + 3.666e-9f / wlsq) / wlsq) * p
+             - 11.2684e-6f * pw) / tk;
+
+    // Beta coefficient (from Stone, with empirical adjustments)
+    float beta = 4.4474e-6f * tk;
+
+    // Refraction constants (from Green)
+    if(refa) *refa = gamma * (1.0f - beta);
+    if(refb) *refb = -gamma * (beta - gamma / 2.0f);
+}
+
+//alt_corrected = alt_apparent + refraction
+float refraction(float phpa, float tc, float rh, float Z_rad){
+    float A, B;
+    refco_f32(phpa, tc, rh, 0.55, &A, &B);
+    float tanZ = tanf(Z_rad);
+    return A * tanZ + B * tanZ * tanZ * tanZ;
+}

G4:G431/CORDIC/astro.h

@@ -0,0 +1,32 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+void set_sincos(int iscordic);
+int get_sincos();
+float MJD_from_unix(uint32_t t);
+//float LST_from_mjd(float mjd);
+float LST_from_unix(uint32_t t);
+float ha_to_ra(float ha, float lst);
+float ra_to_ha(float ra, float lst);
+void altaz_to_hadec(float alt_deg, float az_deg, float *ha_deg, float *dec_deg);
+void hadec_to_altaz(float ha_deg, float dec_deg, float *alt_deg, float *az_deg);
+float refraction(float phpa, float tc, float rh, float Z_rad);

G4:G431/CORDIC/commproto.cpp

@@ -0,0 +1,266 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <cstring>
+
+extern "C"{
+#include <math.h>
+#include <stm32g4.h>
+
+#include "astro.h"
+#include "commproto.h"
+#include "cordic.h"
+#include "hardware.h"
+#include "strfunc.h"
+#include "test.h"
+}
+
+// sending function
+static int (*SEND)(const char *str) = nullptr;
+
+extern volatile uint32_t Tms;
+
+//static uint8_t curbuf[MAXSTRLEN];
+
+// COMMAND(USART,      "Read USART data or send (USART=hex)")
+
+#define STR_HELPER(x) #x
+#define STR(x) STR_HELPER(x)
+
+// list of all commands and handlers
+#define COMMAND_TABLE \
+    COMMAND(help,       "show this help") \
+    COMMAND(sets,       "set sin-cos to cordic (1) or math (0)") \
+    COMMAND(sincos,     "calculate sin/cos for given angle in degrees") \
+    COMMAND(testc,      "test CORDIC function: sincos, sin, cos, atan, sqrt, log") \
+    COMMAND(testm,      "test math function: sin, cos, atan, sqrt, log") \
+    COMMAND(time,       "show MJD and LST for given UNIX-time") \
+
+
+typedef struct {
+    const char *name;
+    const char *desc;
+} CmdInfo;
+
+// prototypes
+#define COMMAND(name, desc)   static errcodes_t cmd_ ## name(const char*, char*);
+COMMAND_TABLE
+#undef COMMAND
+
+static const CmdInfo cmdInfo[] = { // command name, description - for `help`
+#define COMMAND(name, desc)   { #name, desc },
+        COMMAND_TABLE
+#undef COMMAND
+};
+
+static const char* errtxt[ERR_AMOUNT] = {
+    [ERR_OK]        = "OK\n",
+    [ERR_BADCMD]    = "BADCMD\n",
+    [ERR_BADPAR]    = "BADPAR\n",
+    [ERR_BADVAL]    = "BADVAL\n",
+    [ERR_WRONGLEN]  = "WRONGLEN\n",
+    [ERR_CANTRUN]   = "CANTRUN\n",
+    [ERR_BUSY]      = "BUSY\n",
+    [ERR_OVERFLOW]  = "OVERFLOW\n",
+};
+
+const char *EQ = " = "; // equal sign for getters
+
+// send `command = `
+#define CMDEQ()   do{SEND(cmd); SEND(EQ);}while(0)
+// send `commandXXX = `
+#define CMDEQP(x)   do{SEND(cmd); SEND(u2str((uint32_t)x)); SEND(EQ);}while(0)
+// the same as last but with command as option and uint value
+#define SHOWPARU(cmd, x, val)  do{SEND(cmd); SEND(u2str((uint32_t)x)); SEND(EQ); SEND(u2str(val));}while(0)
+
+/**
+ * @brief splitargs - get command parameter and setter from `args`
+ * @param args (i) - rest of string after command (like `1 = PU OD OUT`)
+ * @param parno (o) - parameter number or -1 if none
+ * @return setter (part after `=` without leading spaces) or NULL if none
+ */
+static char *splitargs(char *args, int32_t *parno){
+    if(!args) return NULL;
+    uint32_t U32;
+    char *next = getnum(args, &U32);
+    int p = -1;
+    if(next != args && U32 <= MAXPARNO) p = U32;
+    if(parno) *parno = p;
+    next = strchr(next, '=');
+    if(next){
+        if(*(++next)) next = omit_spaces(next);
+        if(*next == 0) next = NULL;
+    }
+    return next;
+}
+
+/**
+ * @brief argsvals - split `args` into `parno` and setter's value
+ * @param args - rest of string after command
+ * @param parno (o) - parameter number or -1 if none
+ * @param parval - integer setter's value
+ * @return false if no setter or it's not a number, true - got setter's num
+ */
+static bool argsvals(char *args, int32_t *parno, int32_t *parval){
+    char *setter = splitargs(args, parno);
+    if(!setter) return false;
+    int32_t I32;
+    char *next = getint(setter, &I32);
+    if(next != setter){
+        if(parval) *parval = I32;
+        return true;
+    }
+    return false;
+}
+
+static errcodes_t cmd_help(const char*, char*){
+    SEND(REPOURL);
+    for(size_t i = 0; i < sizeof(cmdInfo)/sizeof(cmdInfo[0]); i++){
+        SEND(cmdInfo[i].name);
+        SEND(" - ");
+        SEND(cmdInfo[i].desc); SEND("\n");
+    }
+    return ERR_AMOUNT;
+}
+
+static const char* parse_func_name(char *args){
+    char *setter = splitargs(args, NULL);
+    if(!setter) return nullptr;
+    // remove trailing spaces
+    char *p = setter;
+    while(*p && *p > ' ') ++p;
+    *p = 0;
+    return setter;
+}
+
+// calculate sin/cos
+static errcodes_t cmd_sincos(const char *, char *args){
+    char *setter = splitargs(args, NULL);
+    float f;
+    if(!setter || !getfloat(setter, &f)) return ERR_BADVAL;
+    f = f/180.f * M_PIf;
+    SEND("mathsin="); SEND(float2str(sinf(f), 7));
+    SEND("\nmathcos="); SEND(float2str(cosf(f), 7));
+    float s, c;
+    cordic_sincos(f, &s, &c);
+    SEND("\ncordicsin="); SEND(float2str(s, 7));
+    SEND("\ncordiccos="); SEND(float2str(c, 7));
+    SEND("\n");
+    return ERR_AMOUNT;
+}
+
+// test math function
+static errcodes_t cmd_testm(const char*, char *args){
+    const char *fname = parse_func_name(args);
+    if(!fname) return ERR_BADPAR;
+    uint32_t elapsed = 0;
+    bool ok = true;
+    if(strcmp(fname, "sin") == 0){
+        elapsed = test_math_sin();
+    }else if(strcmp(fname, "cos") == 0){
+        elapsed = test_math_cos();
+    }else if(strcmp(fname, "atan") == 0){
+        elapsed = test_math_atan();
+    }else if(strcmp(fname, "sqrt") == 0){
+        elapsed = test_math_sqrt();
+    }else if(strcmp(fname, "log") == 0){
+        elapsed = test_math_log();
+    }else{
+        ok = false;
+    }
+    if(!ok) return ERR_BADVAL;
+    SEND("TIMEus=");
+    SEND(u2str(elapsed));
+    SEND("\n");
+    return ERR_AMOUNT;
+}
+
+
+// test CORDIC function
+static errcodes_t cmd_testc(const char*, char *args){
+    const char *fname = parse_func_name(args);
+    if(!fname) return ERR_BADPAR;
+    uint32_t elapsed = 0;
+    bool ok = true;
+    if(strcmp(fname, "sincos") == 0){
+        elapsed = test_cordic_sincos();
+    }
+    else if(strcmp(fname, "sin") == 0){
+        elapsed = test_cordic_sin();
+    }else if(strcmp(fname, "cos") == 0){
+        elapsed = test_cordic_cos();
+    }else if(strcmp(fname, "atan") == 0){
+        elapsed = test_cordic_atan();
+    }else if(strcmp(fname, "sqrt") == 0){
+        elapsed = test_cordic_sqrt();
+    }else if(strcmp(fname, "log") == 0){
+        elapsed = test_cordic_log();
+    }else{
+        ok = false;
+    }
+    if(!ok) return ERR_BADVAL;
+    SEND("TIMEus=");
+    SEND(u2str(elapsed));
+    SEND("\n");
+    return ERR_AMOUNT;
+}
+
+static errcodes_t cmd_time(const char *, char *args){
+    char *setter = splitargs(args, NULL);
+    if(!setter) return ERR_BADVAL;
+    uint32_t unix_time;
+    if(setter == getnum(setter, &unix_time)) return ERR_BADVAL;
+    float mjd = MJD_from_unix(unix_time);
+    SEND("MJD="); SEND(float2str(mjd, 7));
+    SEND("\nLST="); SEND(float2str(LST_from_unix(unix_time), 7));
+    SEND("\n");
+    return ERR_AMOUNT;
+}
+
+static errcodes_t cmd_sets(const char *cmd, char *args){
+    int32_t val;
+    if(argsvals(args, NULL, &val)) set_sincos(val);
+    CMDEQ();
+    if(get_sincos()) SEND("CORDIC\n");
+    else SEND("MATH\n");
+    return ERR_AMOUNT;
+}
+
+constexpr uint32_t hash(const char* str, uint32_t h = 0){
+    return *str ? hash(str + 1, h + ((h << 7) ^ *str)) : h;
+}
+
+const char *parse_cmd(int (*sendfun)(const char *), char *str){
+    SEND = sendfun;
+    char command[CMD_MAXLEN+1];
+    int i = 0;
+    while(*str > '@' && i < CMD_MAXLEN){ command[i++] = *str++; }
+    command[i] = 0;
+    while(*str && *str <= ' ') ++str;
+    char *restof = (char*) str;
+    uint32_t h = hash(command);
+    errcodes_t ecode = ERR_AMOUNT;
+    switch(h){
+#define COMMAND(name, desc) case hash(#name): ecode = cmd_ ## name(command, restof); break;
+        COMMAND_TABLE
+#undef COMMAND
+            default: SEND("Unknown command, try 'help'\n"); break;
+    }
+    if(ecode < ERR_AMOUNT) return errtxt[ecode];
+    return NULL;
+}

G4:G431/CORDIC/commproto.h

@@ -0,0 +1,53 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "version.inc"
+
+#ifdef EBUG
+#define RLSDBG "debug"
+#else
+#define RLSDBG "release"
+#endif
+
+#define REPOURL     "https://github.com/eddyem/stm32samples/tree/master/TODO "  RLSDBG " build #" BUILD_NUMBER "@" BUILD_DATE "\n"
+
+
+// error codes for answer message
+typedef enum{
+    ERR_OK,         // all OK
+    ERR_BADCMD,     // wrong command
+    ERR_BADPAR,     // wrong parameter
+    ERR_BADVAL,     // wrong value (for setter)
+    ERR_WRONGLEN,   // wrong message length
+    ERR_CANTRUN,    // can't run given command due to bad parameters or other
+    ERR_BUSY,       // target interface busy, try later
+    ERR_OVERFLOW,   // string was too long -> overflow
+    ERR_AMOUNT      // amount of error codes or "send nothing"
+} errcodes_t;
+
+// maximal length of command (without trailing zero)
+#define CMD_MAXLEN  15
+// maximal available parameter number
+#define MAXPARNO    255
+// maximal string length includint terminating zero
+#define MAXSTRLEN   256
+
+extern const char *EQ;
+const char *parse_cmd(int (*sendfun)(const char*), char *buf);

G4:G431/CORDIC/cordic.c

@@ -0,0 +1,151 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stm32g4.h>
+#include <math.h>
+#include "cordic.h"
+
+// default CSR settings
+#define CORDIC_CSR_DEF  (5 << CORDIC_CSR_PRECISION_Pos)
+
+// enable CORDIC
+static void cordic_enable(void){
+    RCC->AHB1ENR |= RCC_AHB1ENR_CORDICEN;
+    __DSB();
+}
+
+// Convert float to Q1.31 in [-1, 1)
+static int32_t float_to_q31(float x){
+    if(x >= 1.0f) x = 1.0f - 1e-6f;
+    if(x <= -1.0f) x = -1.0f + 1e-6f;
+    return (int32_t)(x * Q31_BASE);
+}
+
+// Convert Q1.31 to float
+static float q31_to_float(int32_t q){
+    return (float)q / Q31_BASE;
+}
+
+static void cordic_init(void){
+    static bool inited = false;
+    if(!inited){
+        cordic_enable();
+        inited = true;
+    }
+}
+
+#if 0
+// Common function for one arg (sin, cos, sqrt, log)
+static float cordic_scalar(uint32_t func_mode, float x, int arg_count){
+    cordic_init();
+    CORDIC->CSR = (func_mode << CORDIC_CSR_FUNC_Pos) |
+                  CORDIC_CSR_INSIZE_1 |            // in Q1.31
+                  CORDIC_CSR_OUTSIZE_0;            // out Q1.31
+    if(arg_count == 1){
+        CORDIC->WDATA = float_to_q31(x);
+    } else {
+...
+    }
+    cordic_wait_ready();
+    int32_t res = CORDIC->RDATA;
+    return q31_to_float(res);
+}
+#endif
+
+// sincos
+void cordic_sincos(float angle, float *s, float *c){
+    float norm = angle / M_PIf;
+    if(norm > 1.0f) norm = 1.0f;
+    if(norm < -1.0f) norm = -1.0f;
+    cordic_init();
+    CORDIC->CSR = (CORDIC_CSR_FUNC_SIN << CORDIC_CSR_FUNC_Pos) | CORDIC_CSR_DEF | CORDIC_CSR_NRES;
+    CORDIC->WDATA = float_to_q31(norm);
+    int32_t res = CORDIC->RDATA;
+    if(s) *s = q31_to_float(res);
+    res = CORDIC->RDATA;
+    if(c) *c = q31_to_float(res);
+}
+
+// sin
+float cordic_sin(float angle){
+    float norm = angle / M_PIf;
+    if(norm > 1.0f) norm = 1.0f;
+    if(norm < -1.0f) norm = -1.0f;
+    cordic_init();
+    CORDIC->CSR = (CORDIC_CSR_FUNC_SIN << CORDIC_CSR_FUNC_Pos) | CORDIC_CSR_DEF;
+    CORDIC->WDATA = float_to_q31(norm);
+    int32_t res = CORDIC->RDATA;
+    return q31_to_float(res);
+}
+
+// cos
+float cordic_cos(float angle){
+    float norm = angle / M_PIf;
+    if(norm > 1.0f) norm = 1.0f;
+    if(norm < -1.0f) norm = -1.0f;
+    cordic_init();
+    CORDIC->CSR = (CORDIC_CSR_FUNC_COS << CORDIC_CSR_FUNC_Pos) | CORDIC_CSR_DEF;
+    CORDIC->WDATA = float_to_q31(norm);
+    int32_t res = CORDIC->RDATA; // cos
+    return q31_to_float(res);
+}
+
+// atan2
+float cordic_atan(float val){
+    if(val > 1.f || val < -1.f) return NAN;
+    cordic_init();
+    CORDIC->CSR = (CORDIC_CSR_FUNC_ATAN << CORDIC_CSR_FUNC_Pos) | CORDIC_CSR_DEF;
+    CORDIC->WDATA = float_to_q31(val);
+    int32_t res = CORDIC->RDATA;
+    return q31_to_float(res) * M_PIf;
+}
+
+// sqrt
+float cordic_sqrt(float x){
+    if(x < 0.0f) x = 0.0f;
+    float scale = 1.0f;
+    if(x > 1.0f){
+        if(x < 100.f){ scale = 10.f; x /= 100.f;}
+        else if(x < 1e4f){ scale = 100.f; x /= 1e4f;}
+        else if(x < 1e6f){ scale = 1e3f; x /= 1e6f;}
+        else if(x < 1e10f){ scale = 1e5f; x /= 1e10f;}
+        else return NAN; // number is too big
+    }
+    cordic_init();
+    CORDIC->CSR = (CORDIC_CSR_FUNC_SQRT << CORDIC_CSR_FUNC_Pos) | CORDIC_CSR_DEF;
+    CORDIC->WDATA = float_to_q31(x);
+    int32_t res = CORDIC->RDATA;
+    return scale * q31_to_float(res);
+}
+
+// log
+float cordic_log(float x){
+    if(x <= 0.0f) x = 0.00001f;
+    float add = 0.f;
+    if(x > 1.0f){
+        if(x < 1000.f){ add = 6.907755279f; x /= 1000.f; }
+        else if(x < 1e6f){ add = 13.815510558f; x /= 1e6f; }
+        else if(x < 1e12f){ add = 27.63102112f; x /= 1e12f; }
+        else return NAN;
+    }
+    cordic_init();
+    CORDIC->CSR = (CORDIC_CSR_FUNC_LOG << CORDIC_CSR_FUNC_Pos) | CORDIC_CSR_DEF;
+    CORDIC->WDATA = float_to_q31(x);
+    int32_t res = CORDIC->RDATA;
+    return q31_to_float(res) * 0.6931471805599453f + add;
+}

G4:G431/CORDIC/cordic.cflags

@@ -0,0 +1 @@
+-std=c23

G4:G431/CORDIC/cordic.config

@@ -0,0 +1,3 @@
+#define EBUG
+#define STM32G4
+#define STM32G431xx

G4:G431/CORDIC/cordic.creator

@@ -0,0 +1 @@
+[General]

G4:G431/CORDIC/cordic.cxxflags

@@ -0,0 +1 @@
+-std=c++23

G4:G431/CORDIC/cordic.files

@@ -0,0 +1,21 @@
+astro.c
+astro.h
+commproto.cpp
+commproto.h
+cordic.c
+cordic.h
+flash.c
+flash.h
+hardware.c
+hardware.h
+main.c
+ringbuffer.c
+ringbuffer.h
+servo.c
+servo.h
+strfunc.c
+strfunc.h
+test.c
+test.h
+usart.c
+usart.h

G4:G431/CORDIC/cordic.h

@@ -0,0 +1,47 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#ifndef M_PIf
+#define M_PIf       3.141592653589793f
+#endif
+
+#define Q31_BASE    2147483648.0f
+
+// functions
+enum {
+    CORDIC_CSR_FUNC_COS = 0,
+    CORDIC_CSR_FUNC_SIN,
+    CORDIC_CSR_FUNC_PHASE,
+    CORDIC_CSR_FUNC_MOD,
+    CORDIC_CSR_FUNC_ATAN,
+    CORDIC_CSR_FUNC_COSH,
+    CORDIC_CSR_FUNC_ATANH,
+    CORDIC_CSR_FUNC_LOG,
+    CORDIC_CSR_FUNC_SQRT
+};
+
+void  cordic_sincos(float angle, float *s, float *c);
+float cordic_sin(float angle);
+float cordic_cos(float angle);
+float cordic_atan(float val);
+float cordic_sqrt(float x);
+float cordic_log(float x);

G4:G431/CORDIC/cordic.includes

@@ -0,0 +1,4 @@
+.
+../inc
+../inc/Fx
+../inc/cm

G4:G431/CORDIC/hardware.c

@@ -0,0 +1,69 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stm32g4.h>
+
+#include "hardware.h"
+
+volatile uint32_t Tms = 0;
+
+/* Called when systick fires */
+void sys_tick_handler(){
+    ++Tms;
+}
+
+static void timer_setup(){
+    RCC->APB1ENR1 |= RCC_APB1ENR1_TIM3EN;
+    __DSB();
+    TIM3->CR1 = 0;              // disable counter
+    TIM3->PSC = 84;             // 85 MHz / 85 = 1 MHz
+    TIM3->ARR = 0xFFFFFFFF;     // 32-bit auto-reload (maximum)
+}
+
+void timer_start(){
+    TIM3->CNT = 0;
+    TIM3->CR1 = TIM_CR1_CEN;
+}
+
+void timer_stop(){
+    TIM3->CR1 = 0;
+}
+
+uint32_t timer_read(){
+    return TIM3->CNT;
+}
+
+void gpio_setup(){
+    RCC->AHB2ENR = RCC_AHB2ENR_GPIOAEN | RCC_AHB2ENR_GPIOCEN;
+    __DSB();
+    // PC6 as output, PC13 as input with pulldown
+    GPIOC->MODER = (0xffffffff & ~(GPIO_MODER_MODE6 | GPIO_MODER_MODE13)) | MODER_O(6) | MODER_I(13);
+    GPIOC->PUPDR = PUPD_PD(13);
+    GPIOC->OTYPER = OTYPER_PP(6);
+    // PA9 (Tx), PA10 (Rx) as alternate functions (for USART1)
+    GPIOA->MODER = (0xabffffff & ~(GPIO_MODER_MODE9 | GPIO_MODER_MODE10)) |
+                   MODER_AF(9) | MODER_AF(10);
+    GPIOA->AFR[1] = AFRf(7, 9) | AFRf(7, 10);
+    // count milliseconds
+    SysTick_Config(SysFreq / 1000);
+
+    // Setup TIM3 for microsecond counting
+    timer_setup();
+}
+
+

G4:G431/CORDIC/hardware.h

@@ -0,0 +1,43 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+// KEY (intpullup->0) - PC13
+// LED - PC6
+#define KEY_PORT    GPIOC
+#define KEY_PIN     (1<<13)
+#define LED_PORT    GPIOC
+#define LED_PIN     (1<<6)
+#define KEY_PRESSED() (pin_read(KEY_PORT, KEY_PIN) == 1)
+#define LED_ON()    do{pin_set(LED_PORT, LED_PIN);}while(0)
+#define LED_OFF()   do{pin_clear(LED_PORT, LED_PIN);}while(0)
+#define LED_TOGG()  do{pin_toggle(LED_PORT, LED_PIN);}while(0)
+
+#define SERVO_AMOUNT    4
+
+#define MIN_USART_SPEED 1200
+#define MAX_USART_SPEED 3000000
+
+extern volatile uint32_t Tms;
+
+void gpio_setup();
+
+void timer_start();
+void timer_stop();
+uint32_t timer_read();

G4:G431/CORDIC/main.c

@@ -0,0 +1,71 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2023 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stm32g4.h>
+#include <string.h>
+
+#include "commproto.h"
+#include "hardware.h"
+#include "strfunc.h"
+#include "usart.h"
+
+// 40ms for debouncing
+#define TDEBOUNCE   (40)
+
+int main(void){
+    StartHSE();
+    // init storage first to take base values
+    gpio_setup();
+    usart_setup(115200);
+    bool pressed = false;
+    uint32_t Tblink = 0, Tkey = 0; // blink and key pressed time
+    uint32_t Tpressed = 0;
+    while(1){
+        USART_flags_t f = usart_process();
+        if(f.rxovrfl) usart_sendstr("Rx buffer overflow!\n");
+        if(f.txerr) usart_sendstr("Tx error!\n");
+        char *str = usart_getline();
+        if(str){
+            const char *ans = parse_cmd(usart_sendstr, str);
+            if(ans) usart_sendstr(ans);
+        }
+        if(Tms - Tblink > 499){
+            LED_TOGG();
+            Tblink = Tms;
+        }
+        if(KEY_PRESSED()){
+            if(!pressed){ // new event
+                pressed = true;
+                usart_sendstr("Key pressed\n");
+                timer_start();
+                Tpressed = Tms;
+            }
+            Tkey = Tms;
+        }else{ // key released
+            if(pressed && (Tms - Tkey) > TDEBOUNCE){ // wait for debounce
+                timer_stop();
+                uint32_t micros = timer_read();
+                uint32_t millis = Tms - Tpressed;
+                pressed = false;
+                usart_sendstr("Key released\n");
+                usart_sendstr("Tms="); usart_sendstr(u2str(millis));
+                usart_sendstr("\nTus="); usart_sendstr(u2str(micros)); usart_sendstr("\n");
+            }
+        }
+    }
+}

G4:G431/CORDIC/openocd.cfg

@@ -0,0 +1,4 @@
+set FLASH_SIZE 0x20000
+
+source [find interface/stlink-v2-1.cfg]
+source [find target/stm32g4x.cfg]

G4:G431/CORDIC/ringbuffer.c

@@ -0,0 +1,203 @@
+/*
+ * Copyright 2023 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+#include <stm32g4.h>
+#include "ringbuffer.h"
+
+#define CHK(b)  do{if(!b) return -1;}while(0)
+
+static int datalen(ringbuffer *b){
+    if(b->tail >= b->head) return (b->tail - b->head);
+    else return (b->length - b->head + b->tail);
+}
+
+// stored data length
+int RB_datalen(ringbuffer *b){
+    CHK(b);
+    if(0 == datalen(b)) return 0; // don't block for empty RO operations
+    if(b->busy) return -1;
+    b->busy = true;
+    int l = datalen(b);
+    b->busy = false;
+    return l;
+}
+
+static int hasbyte(ringbuffer *b, uint8_t byte){
+    if(b->head == b->tail) return -1; // no data in buffer
+    int startidx = b->head;
+    if(b->head > b->tail){ //
+        for(int found = b->head; found < b->length; ++found)
+            if(b->data[found] == byte) return found;
+        startidx = 0;
+    }
+    for(int found = startidx; found < b->tail; ++found)
+        if(b->data[found] == byte) return found;
+    return -1;
+}
+
+/**
+ * @brief RB_hasbyte - check if buffer has given byte stored
+ * @param b - buffer
+ * @param byte - byte to find
+ * @return index if found, -1 if none or busy
+ */
+int RB_hasbyte(ringbuffer *b, uint8_t byte){
+    CHK(b);
+    if(b->busy) return -1;
+    b->busy = true;
+    int ret = hasbyte(b, byte);
+    b->busy = false;
+    return ret;
+}
+
+// increment head or tail
+TRUE_INLINE void incr(ringbuffer *b, volatile int *what, int n){
+    *what += n;
+    if(*what >= b->length) *what -= b->length;
+}
+
+static int read(ringbuffer *b, uint8_t *s, int len){
+    int l = datalen(b);
+    if(!l) return 0;
+    if(l > len) l = len;
+    int _1st = b->length - b->head;
+    if(_1st > l) _1st = l;
+    if(_1st > len) _1st = len;
+    memcpy(s, b->data + b->head, _1st);
+    if(_1st < len && l > _1st){
+        memcpy(s+_1st, b->data, l - _1st);
+        incr(b, &b->head, l);
+        return l;
+    }
+    incr(b, &b->head, _1st);
+    return _1st;
+}
+
+/**
+ * @brief RB_read - read data from ringbuffer
+ * @param b - buffer
+ * @param s - array to write data
+ * @param len - max len of `s`
+ * @return bytes read or -1 if busy
+ */
+int RB_read(ringbuffer *b, uint8_t *s, int len){
+    CHK(b);
+    if(!s || len < 1) return -1;
+    if(0 == datalen(b)) return 0;
+    if(b->busy) return -1;
+    b->busy = true;
+    int r = read(b, s, len);
+    b->busy = false;
+    return r;
+}
+
+// length of data from current position to `byte` (including byte)
+static int lento(ringbuffer *b, uint8_t byte){
+    int idx = hasbyte(b, byte);
+    if(idx < 0) return 0;
+    int partlen = idx + 1 - b->head;
+    // now calculate length of new data portion
+    if(idx < b->head) partlen += b->length;
+    return partlen;
+}
+
+static int readto(ringbuffer *b, uint8_t byte, uint8_t *s, int len){
+    int partlen = lento(b, byte);
+    if(!partlen) return 0;
+    if(partlen > len) return -1;
+    return read(b, s, partlen);
+}
+
+/**
+ * @brief RB_readto fill array `s` with data until byte `byte` (with it)
+ * @param b - ringbuffer
+ * @param byte - check byte
+ * @param s - buffer to write data or NULL to clear data
+ * @param len - length of `s` or 0 to clear data
+ * @return amount of bytes written (negative, if len<data in buffer or buffer is busy)
+ */
+int RB_readto(ringbuffer *b, uint8_t byte, uint8_t *s, int len){
+    CHK(b);
+    if(!s || len < 1) return -1;
+    if(0 == datalen(b)) return 0;
+    if(b->busy) return -1;
+    b->busy = true;
+    int n = 0;
+    if(s && len > 0){
+        n = readto(b, byte, s, len);
+    }else{
+        incr(b, &b->head, lento(b, byte)); // just throw data out
+    }
+    b->busy = false;
+    return n;
+}
+
+int RB_datalento(ringbuffer *b, uint8_t byte){
+    CHK(b);
+    if(0 == datalen(b)) return 0;
+    if(b->busy) return -1;
+    b->busy = true;
+    int n = lento(b, byte);
+    b->busy = false;
+    return n;
+}
+
+// if l < rest of buffer, truncate and return actually written bytes
+static int write(ringbuffer *b, const uint8_t *str, int l){
+    int r = b->length - 1 - datalen(b); // rest length
+    if(r < 1) return 0;
+    if(l > r) l = r;
+    int _1st = b->length - b->tail;
+    if(_1st > l) _1st = l;
+    memcpy(b->data + b->tail, str, _1st);
+    if(_1st < l){ // add another piece from start
+        memcpy(b->data, str+_1st, l-_1st);
+    }
+    incr(b, &b->tail, l);
+    return l;
+}
+
+/**
+ * @brief RB_write - write some data to ringbuffer
+ * @param b - buffer
+ * @param str - data
+ * @param l - length
+ * @return amount of bytes written or -1 if busy
+ */
+int RB_write(ringbuffer *b, const uint8_t *str, int l){
+    CHK(b);
+    if(!str || l < 1) return -1;
+    if(b->length - datalen(b) < 2) return 0;
+    if(b->busy) return -1;
+    b->busy = true;
+    int w = write(b, str, l);
+    b->busy = false;
+    return w;
+}
+
+// just delete all information in buffer `b`
+int RB_clearbuf(ringbuffer *b){
+    CHK(b);
+    if(b->busy) return -1;
+    b->busy = true;
+    b->head = 0;
+    b->tail = 0;
+    memset(b->data, 0, b->length);
+    b->busy = false;
+    return 1;
+}

G4:G431/CORDIC/ringbuffer.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2023 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+typedef struct{
+    uint8_t *data;      // data buffer
+    const int length;   // its length
+    int head;           // head index
+    int tail;           // tail index
+    volatile bool busy; // == TRUE if buffer is busy now
+} ringbuffer;
+
+int RB_read(ringbuffer *b, uint8_t *s, int len);
+int RB_readto(ringbuffer *b, uint8_t byte, uint8_t *s, int len);
+int RB_hasbyte(ringbuffer *b, uint8_t byte);
+int RB_write(ringbuffer *b, const uint8_t *str, int l);
+int RB_datalen(ringbuffer *b);
+int RB_datalento(ringbuffer *b, uint8_t byte);
+int RB_clearbuf(ringbuffer *b);

G4:G431/CORDIC/strfunc.c

@@ -0,0 +1,378 @@
+/*
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <math.h> // isnan/isinf
+#include <stm32g4.h>
+#include <string.h>
+
+/**
+ * @brief hexdump - dump hex array by 16 bytes in string
+ * @param arr - array to dump
+ * @param len - length of `arr`
+ */
+void hexdump(int (*sendfun)(const char *), uint8_t *arr, uint16_t len){
+    char buf[52], *bptr = buf;
+    for(uint16_t l = 0; l < len; ++l, ++arr){
+        for(int16_t j = 1; j > -1; --j){
+            register uint8_t half = (*arr >> (4*j)) & 0x0f;
+            if(half < 10) *bptr++ = half + '0';
+            else *bptr++ = half - 10 + 'a';
+        }
+        if(l % 16 == 15){
+            *bptr++ = '\n';
+            *bptr = 0;
+            sendfun(buf);
+            bptr = buf;
+        }else *bptr++ = ' ';
+    }
+    if(bptr != buf){
+        *bptr++ = '\n';
+        *bptr = 0;
+        sendfun(buf);
+    }
+}
+
+/**
+ * @brief _2str - convert value into string buffer
+ * @param val - |value|
+ * @param minus - ==0 if value > 0
+ * @return buffer with number
+ */
+static char *_2str(uint32_t  val, uint8_t minus){
+    static char strbuf[12];
+    char *bufptr = &strbuf[11];
+    *bufptr = 0;
+    if(!val){
+        *(--bufptr) = '0';
+    }else{
+        while(val){
+            uint32_t x = val / 10;
+            *(--bufptr) = (val - 10*x) + '0';
+            val = x;
+        }
+    }
+    if(minus) *(--bufptr) = '-';
+    return bufptr;
+}
+
+// return string with number `val`
+char *u2str(uint32_t val){
+    return _2str(val, 0);
+}
+char *i2str(int32_t i){
+    uint8_t minus = 0;
+    uint32_t val;
+    if(i < 0){
+        minus = 1;
+        val = -i;
+    }else val = i;
+    return _2str(val, minus);
+}
+
+/**
+ * @brief uhex2str - print 32bit unsigned int as hex
+ * @param val - value
+ * @return string with number
+ */
+char *uhex2str(uint32_t val){
+    static char buf[12] = "0x";
+    int npos = 2;
+    uint8_t *ptr = (uint8_t*)&val + 3;
+    int8_t i, j, z=1;
+    for(i = 0; i < 4; ++i, --ptr){
+        if(*ptr == 0){ // omit leading zeros
+            if(i == 3) z = 0;
+            if(z) continue;
+        }
+        else z = 0;
+        for(j = 1; j > -1; --j){
+            uint8_t half = (*ptr >> (4*j)) & 0x0f;
+            if(half < 10) buf[npos++] = half + '0';
+            else buf[npos++] = half - 10 + 'a';
+        }
+    }
+    buf[npos] = 0;
+    return buf;
+}
+
+/**
+ * @brief omit_spaces - eliminate leading spaces and other trash in string
+ * @param buf - string
+ * @return - pointer to first character in `buf` > ' '
+ */
+char *omit_spaces(char *buf){
+    while(*buf){
+        if(*buf > ' ') break;
+        ++buf;
+    }
+    return buf;
+}
+
+/**
+ * @brief getdec - read decimal number & return pointer to next non-number symbol
+ * @param buf - string
+ * @param N - number read
+ * @return Next non-number symbol. In case of overflow return `buf` and N==0xffffffff
+ */
+static char *getdec(char *buf, uint32_t *N){
+    char *start = (char*)buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        if(c < '0' || c > '9'){
+            break;
+        }
+        if(num > 429496729 || (num == 429496729 && c > '5')){ // overflow
+            *N = 0xffffff;
+            return start;
+        }
+        num *= 10;
+        num += c - '0';
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+// read hexadecimal number (without 0x prefix!)
+char *gethex(char *buf, uint32_t *N){
+    char *start = buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        uint8_t M = 0;
+        if(c >= '0' && c <= '9'){
+            M = '0';
+        }else if(c >= 'A' && c <= 'F'){
+            M = 'A' - 10;
+        }else if(c >= 'a' && c <= 'f'){
+            M = 'a' - 10;
+        }
+        if(M){
+            if(num & 0xf0000000){ // overflow
+                *N = 0xffffff;
+                return start;
+            }
+            num <<= 4;
+            num += c - M;
+        }else{
+            break;
+        }
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+// read octal number (without 0 prefix!)
+static char *getoct(char *buf, uint32_t *N){
+    char *start = (char*)buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        if(c < '0' || c > '7'){
+            break;
+        }
+        if(num & 0xe0000000){ // overflow
+            *N = 0xffffff;
+            return start;
+        }
+        num <<= 3;
+        num += c - '0';
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+// read binary number (without b prefix!)
+static char *getbin(char *buf, uint32_t *N){
+    char *start = (char*)buf;
+    uint32_t num = 0;
+    while(*buf){
+        char c = *buf;
+        if(c < '0' || c > '1'){
+            break;
+        }
+        if(num & 0x80000000){ // overflow
+            *N = 0xffffff;
+            return start;
+        }
+        num <<= 1;
+        if(c == '1') num |= 1;
+        ++buf;
+    }
+    *N = num;
+    return buf;
+}
+
+/**
+ * @brief getnum - read uint32_t from string (dec, hex or bin: 127, 0x7f, 0b1111111)
+ * @param buf - buffer with number and so on
+ * @param N   - the number read
+ * @return pointer to first non-number symbol in buf
+ *      (if it is == buf, there's no number or if *N==0xffffffff there was overflow)
+ */
+char *getnum(char *txt, uint32_t *N){
+    char *nxt = NULL;
+    char *s = omit_spaces(txt);
+    if(*s == '0'){ // hex, oct or 0
+        if(s[1] == 'x' || s[1] == 'X'){ // hex
+            nxt = gethex(s+2, N);
+            if(nxt == s+2) nxt = (char*)txt;
+        }else if(s[1] > '0'-1 && s[1] < '8'){ // oct
+            nxt = getoct(s+1, N);
+            if(nxt == s+1) nxt = (char*)txt;
+        }else{ // 0
+            nxt = s+1;
+            *N = 0;
+        }
+    }else if(*s == 'b' || *s == 'B'){
+        nxt = getbin(s+1, N);
+        if(nxt == s+1) nxt = (char*)txt;
+    }else{
+        nxt = getdec(s, N);
+        if(nxt == s) nxt = (char*)txt;
+    }
+    return nxt;
+}
+
+// get signed integer
+char *getint(char *txt, int32_t *I){
+    char *s = omit_spaces(txt);
+    int32_t sign = 1;
+    uint32_t U;
+    if(*s == '-'){
+        sign = -1;
+        ++s;
+    }
+    char *nxt = getnum(s, &U);
+    if(nxt == s) return txt;
+    if(U & 0x80000000) return txt; // overfull
+    *I = sign * (int32_t)U;
+    return nxt;
+}
+
+// be careful: if pow10 would be bigger you should change str[] size!
+static const float pwr10[] = {1.f,   10.f,  100.f,  1000.f,  10000.f,  100000.f,  1000000.f,  10000000.f};
+static const float rounds[] = {0.5f, 0.05f, 0.005f, 0.0005f, 0.00005f, 0.000005f, 0.0000005f, 0.00000005f};
+#define P10L  (sizeof(pwr10)/sizeof(float) - 1)
+char *float2str(float x, uint8_t prec){
+    static char str[16] = {0}; // -117.5494E-36\0 - 14 symbols max!
+    if(prec > P10L) prec = P10L;
+    if(isnan(x)){ memcpy(str, "NAN", 4); return str;}
+    else{
+        int i = isinf(x);
+        if(i){memcpy(str, "-INF", 5); if(i == 1) return str+1; else return str;}
+    }
+    char *s = str + 14; // go to end of buffer
+    uint8_t minus = 0;
+    if(x < 0){
+        x = -x;
+        minus = 1;
+    }
+    int pow = 0; // xxxEpow
+    // now convert float to 1.xxxE3y
+    while(x > 1000.f){
+        x /= 1000.f;
+        pow += 3;
+    }
+    if(x > 0.) while(x < 1.){
+            x *= 1000.f;
+            pow -= 3;
+        }
+    // print Eyy
+    if(pow){
+        uint8_t m = 0;
+        if(pow < 0){pow = -pow; m = 1;}
+        while(pow){
+            int p10 = pow/10;
+            *s-- = '0' + (pow - 10*p10);
+            pow = p10;
+        }
+        if(m) *s-- = '-';
+        *s-- = 'E';
+    }
+    // now our number is in [1, 1000]
+    uint32_t units;
+    if(prec){
+        units = (uint32_t) x;
+        uint32_t decimals = (uint32_t)((x-units+rounds[prec])*pwr10[prec]);
+        // print decimals
+        while(prec){
+            int d10 = decimals / 10;
+            *s-- = '0' + (decimals - 10*d10);
+            decimals = d10;
+            --prec;
+        }
+        // decimal point
+        *s-- = '.';
+    }else{ // without decimal part
+        units = (uint32_t) (x + 0.5);
+    }
+    // print main units
+    if(units == 0) *s-- = '0';
+    else while(units){
+            uint32_t u10 = units / 10;
+            *s-- = '0' + (units - 10*u10);
+            units = u10;
+        }
+    if(minus) *s-- = '-';
+    return s+1;
+}
+
+char *getfloat(char *str, float *f){
+    str = omit_spaces(str);
+    int isminus = 0;
+    if(*str == '-'){
+        isminus = 1;
+        ++str;
+    }else if (*str == '+'){
+        ++str;
+    }
+    float result = 0.0f;
+    while(*str >= '0' && *str <= '9'){
+        result = result * 10.0f + (float)(*str - '0');
+        ++str;
+    }
+    if(*str != '.') goto retn;
+
+    ++str; // omit point
+    float frac = 0.0f;
+    float divisor = 1.0f;
+
+    while(*str >= '0' && *str <= '9'){
+        divisor *= 10.0f;
+        frac = frac * 10.0f + (float)(*str - '0');
+        ++str;
+    }
+
+    if(divisor > 1.0f){
+        result += frac / divisor;
+    }
+
+    if(*str == 'e' || *str == 'E'){ // exp
+        ++str;
+        int32_t E;
+        if(str != getint(str, &E)){
+            if(E > 0) while(E-- > 0) result *= 10.f;
+            else while(E++ < 0) result /= 10.f;
+        }
+    }
+
+retn:
+    if(f) *f = (isminus) ? -result : result;
+    return str;
+}
+

G4:G431/CORDIC/strfunc.h

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+char *omit_spaces(char *buf);
+void hexdump(int (*sendfun)(const char*), uint8_t *arr, uint16_t len);
+char *u2str(uint32_t val);
+char *i2str(int32_t i);
+char *float2str(float x, uint8_t prec);
+char *uhex2str(uint32_t val);
+char *gethex(const char *buf, uint32_t *N);
+char *getnum(char *txt, uint32_t *N);
+char *getint(char *txt, int32_t *I);
+char *getfloat(char *str, float *f);

G4:G431/CORDIC/test.c

@@ -0,0 +1,127 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <math.h>
+#include <stdint.h>
+#include <stm32g4.h>
+
+#include "test.h"
+#include "hardware.h"
+#include "cordic.h"
+
+// amount of iterations over test
+#define N_TESTS     1000
+
+static float arr[N_TESTS];
+
+
+// RNG
+static uint32_t rand_state = 123456789;
+static uint32_t next_rand(){
+    rand_state = rand_state * 1664525 + 1013904223;
+    return rand_state;
+}
+
+// fill array with random angles
+static void fill_random_sin_cos(){
+    for(int i = 0; i < N_TESTS; ++i){
+        // angle from -pi to +pi
+        arr[i] = (float)(next_rand() % 62831853) / 10000000.0f - 3.14159265f;
+    }
+}
+
+static void fill_random_atan(){
+    for(int i = 0; i < N_TESTS; ++i){
+        arr[i] = (float)(next_rand() % 2000000) / 1e6f - 1e6f; // [-1,1]
+    }
+}
+
+static void fill_random_sqrt(){
+    for(int i = 0; i < N_TESTS; ++i){
+        arr[i] = (float)(next_rand() % 10000) / 100.0f; // [0,100]
+    }
+}
+
+static void fill_random_log(){
+    for(int i = 0; i < N_TESTS; ++i){
+        arr[i] = (float)(next_rand() % 10000 + 1) / 100.0f; // [0.01, 100]
+    }
+}
+
+// main test template
+static uint32_t run_test(void (*gen)(), float (*func)(float)){
+    gen();
+    volatile float result = 0.0f; // don't let gcc to optimize this cycle
+    timer_start();
+    for(int i = 0; i < N_TESTS; ++i){
+        result = func(arr[i]);
+        (void) result;
+    }
+    timer_stop();
+    return timer_read();
+}
+
+static uint32_t run_test2(void (*gen)(), void (*func)(float, float*, float*)){
+    gen();
+    volatile float result1 = 0.f, result2 = 0.f; // don't let gcc to optimize this cycle
+    timer_start();
+    for(int i = 0; i < N_TESTS; ++i){
+        func(arr[i], (float*)&result1, (float*)&result2);
+        (void) result1;
+        (void) result2;
+    }
+    timer_stop();
+    return timer_read();
+}
+
+// ------------- math.h tests -------------
+uint32_t test_math_sin(){
+    return run_test(fill_random_sin_cos, sinf);
+}
+uint32_t test_math_cos(){
+    return run_test(fill_random_sin_cos, cosf);
+}
+uint32_t test_math_atan(){
+    return run_test(fill_random_atan, atanf);
+}
+uint32_t test_math_sqrt(){
+    return run_test(fill_random_sqrt, sqrtf);
+}
+uint32_t test_math_log(){
+    return run_test(fill_random_log, logf);
+}
+
+// ------------- CORDIC tests -------------
+uint32_t test_cordic_sincos(){
+    return run_test2(fill_random_sin_cos, cordic_sincos);
+}
+uint32_t test_cordic_sin(){
+    return run_test(fill_random_sin_cos, cordic_sin);
+}
+uint32_t test_cordic_cos(){
+    return run_test(fill_random_sin_cos, cordic_cos);
+}
+uint32_t test_cordic_atan(){
+    return run_test(fill_random_atan, cordic_atan);
+}
+uint32_t test_cordic_sqrt(){
+    return run_test(fill_random_sqrt, cordic_sqrt);
+}
+uint32_t test_cordic_log(){
+    return run_test(fill_random_log, cordic_log);
+}

G4:G431/CORDIC/test.h

@@ -0,0 +1,36 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+// libmath tests
+uint32_t test_math_sin();
+uint32_t test_math_cos();
+uint32_t test_math_atan();
+uint32_t test_math_sqrt();
+uint32_t test_math_log();
+
+// CORDIC tests
+uint32_t test_cordic_sincos();
+uint32_t test_cordic_sin();
+uint32_t test_cordic_cos();
+uint32_t test_cordic_atan();
+uint32_t test_cordic_sqrt();
+uint32_t test_cordic_log();

G4:G431/CORDIC/usart.c

@@ -0,0 +1,257 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stm32g4.h>
+#include <string.h>
+
+#include "hardware.h" // Tms
+#include "ringbuffer.h"
+#include "usart.h"
+
+// USART for text-based protocol, each data portion ends with '\n'
+// RX works over circular DMA
+
+// USART-depending part ------->
+// USART1 @ PA9 (Tx) - MUX25 - and PA10 (Rx) - MUX24
+// select USART and its DMA channels
+#define USARTx      USART1
+#define USARTxAPB   APB2ENR
+#define USARTxEN    RCC_APB2ENR_USART1EN
+#define USART_APBEN RCC_APB2
+// DMAMUX channels: 24 - USART1Rx, 25 - USART1Tx
+#define DMAMUXRXN   (24)
+#define DMAMUXTXN   (25)
+// DMA channels: 1 (0 in MUX) - Rx, 2 (1 in MUX) - Tx; TC and error flags
+// use DMA ch2/3 because they both have single IRQ
+#define DMAx        DMA1
+#define DMAxEN      (RCC_AHB1ENR_DMA1EN | RCC_AHB1ENR_DMAMUX1EN)
+#define DMACHRX     DMA1_Channel1
+#define DMARXTCF    DMA_ISR_TCIF1
+#define DMARXEF     DMA_ISR_TEIF1
+#define DMACHTX     DMA1_Channel2
+#define DMATXTCF    DMA_ISR_TCIF2
+#define DMATXEF     DMA_ISR_TEIF2
+#define DMAMUXRX    DMAMUX1_Channel0
+#define DMAMUXTX    DMAMUX1_Channel1
+#define USARTIRQn   USART1_IRQn
+#define DMARXIRQ    DMA1_Channel1_IRQn
+#define DMATXIRQ    DMA1_Channel2_IRQn
+
+// interrupt aliases
+static void usart_isr();
+static void dmatx_isr();
+static void dmarx_isr();
+void usart1_isr() __attribute__ ((alias ("usart_isr")));
+void dma1_channel1_isr() __attribute__ ((alias ("dmarx_isr")));
+void dma1_channel2_isr() __attribute__ ((alias ("dmatx_isr")));
+// <-------- USART-depending part
+
+// RX/TX DMA->CCR without EN flag
+#define DMARXCCR    (DMA_CCR_MINC | DMA_CCR_CIRC | DMA_CCR_TEIE)
+#define DMATXCCR    (DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE | DMA_CCR_TEIE)
+
+static volatile bool gotstring = true; // got '\n' in input stream -> force data reading to inbuf
+static volatile bool txrdy = true; // Tx DMA not busy
+static volatile USART_flags_t curflags; // current flags (cleared in `usart_process`)
+// rx/tx DMA buffers
+static uint8_t dmarxbuf[USARTRXDMABUFSZ];
+static uint8_t dmatxbuf[USARTTXDMABUFSZ];
+// index of last DMA read position
+static uint32_t dma_read_idx = 0;
+// for ringbuffer
+static uint8_t rbrxbuf[USARTRXBUFSZ], rbtxbuf[USARTTXBUFSZ];
+static ringbuffer TxRB = {.data = rbtxbuf, .length = USARTTXBUFSZ};
+static ringbuffer RxRB = {.data = rbrxbuf, .length = USARTRXBUFSZ};
+
+#define USART_BRR(speed)    ((SysFreq + (speed)/2) / (speed))
+
+static void reinit_rx_dma(){
+    dma_read_idx = 0;
+    RB_clearbuf(&RxRB);
+    DMACHRX->CCR = DMARXCCR; // stop to reload
+    DMACHRX->CNDTR = USARTRXDMABUFSZ;
+    DMACHRX->CMAR = (uint32_t) dmarxbuf;
+    DMACHRX->CCR = DMARXCCR | DMA_CCR_EN;
+}
+
+void usart_setup(uint32_t speed){
+    RCC->AHB1ENR |= DMAxEN; // enable DMA
+    // enable USART clocking
+    RCC->USARTxAPB |= USARTxEN;
+    // baudrate
+    USARTx->BRR = USART_BRR(speed);
+    // eol character: '/n'
+    USARTx->CR2 = USART_CR2_ADD_VAL('\n');
+    // enable DMA transmission
+    USARTx->CR3 = USART_CR3_DMAT | USART_CR3_DMAR;
+    // set up DMA channels
+    // Tx channel: mem++, mem->periph, 8bit, compl.&err. irq
+    DMACHTX->CCR = DMATXCCR;
+    DMACHTX->CPAR = (uint32_t) &USARTx->TDR; // peripherial address
+    // Rx channel: mem++, periph->mem, 8bit, compl.&err. irq
+    DMACHRX->CCR = DMARXCCR;
+    DMACHRX->CPAR = (uint32_t) &USARTx->RDR; // peripherial address
+    // set up DMAMUX channels
+    // enumeration of DMAMUX starts from 0 (DMA - from 1)!
+    DMAMUXRX->CCR = DMAMUXRXN;
+    DMAMUXTX->CCR = DMAMUXTXN;
+    // charmatch interrupt, enable transmitter and receiver, enable usart
+    USARTx->CR1 = USART_CR1_CMIE | USART_CR1_TE | USART_CR1_RE | USART_CR1_UE;
+    USARTx->ICR = 0xffffffff; // clear all flags
+    reinit_rx_dma();
+    NVIC_EnableIRQ(USARTIRQn);
+    NVIC_EnableIRQ(DMARXIRQ);
+    NVIC_EnableIRQ(DMATXIRQ);
+}
+
+/**
+ * @brief usart_sendbuf - send next data portion
+ * @return true if sent something
+ */
+static bool usart_sendbuf(){
+    if(!txrdy) return false;
+    int rd = RB_read(&TxRB, dmatxbuf, USARTTXDMABUFSZ);
+    if(rd < 1) return false; // nothing to write or busy
+    // set up DMA
+    DMACHTX->CCR = DMATXCCR;
+    DMACHTX->CMAR = (uint32_t) dmatxbuf;
+    DMACHTX->CNDTR = rd;
+    USARTx->ICR = USART_ICR_TCCF; // clear TC flag
+    txrdy = false;
+    // activate DMA
+    DMACHTX->CCR = DMATXCCR | DMA_CCR_EN;
+    return true;
+}
+
+int usart_send(const char *str, int len){
+    if(!str || len < 1) return 0;
+    uint32_t t = Tms;
+    int sent = 0;
+    do{
+        IWDG->KR = IWDG_REFRESH;
+        int put = RB_write(&TxRB, (uint8_t*)str, len);
+        if(put < 0) continue; // busy
+        else if(put == 0){
+            usart_sendbuf(); // no place
+            t = Tms;
+        }else{
+            len -= put;
+            sent += put;
+            str += put;
+        }
+    }while(len && (Tms - t) < USARTBLKTMOUT); // not more than `block` ms!
+    return sent;
+}
+
+int usart_sendstr(const char *str){
+    int l = strlen(str);
+    return usart_send(str, l);
+}
+
+static void addtoreadidx(int adder){
+    dma_read_idx += adder;
+    if(dma_read_idx >= USARTRXDMABUFSZ) dma_read_idx -= USARTRXDMABUFSZ;
+}
+
+// return current flags
+USART_flags_t usart_process(){
+    static uint32_t Tlast = 0;
+    USART_flags_t flags = curflags;
+    curflags.all = 0;
+    if(RB_datalento(&TxRB, '\n') > 1 || Tms - Tlast >= USARTSENDTMOUT){ // send buffer as we found '\n' or each 10ms
+        if(usart_sendbuf()) Tlast = Tms;
+    }
+    int remained = DMACHRX->CNDTR;
+    int write_idx = USARTRXDMABUFSZ - remained; // next symbol to be written
+    int available = (write_idx - dma_read_idx); // length of data available
+    if(available < 0) available += USARTRXDMABUFSZ; // write to the left of read
+    if(available == 0) return flags;
+    // add next data portion to RX ring buffer
+    if(available >= (USARTRXDMABUFSZ / 2) || gotstring){
+        // copy data in one or two chunks (wrap handling)
+        // check if we can write to RB `available` bytes
+        int rballow = RxRB.length - 1 - RB_datalen(&RxRB);
+        if(rballow < available){
+            if(available > USARTRXDMABUFSZ - 2){ // near overfull
+                flags.rxovrfl = 1;
+                reinit_rx_dma();
+                RB_clearbuf(&RxRB);
+                return flags;
+            }
+            if(rballow < 1) return flags;
+            available = rballow; // read at least as we can
+        }
+        if(dma_read_idx + available <= USARTRXDMABUFSZ){ // head before tail
+            int written = RB_write(&RxRB, &dmarxbuf[dma_read_idx], available);
+            if(written == available && dmarxbuf[dma_read_idx+available-1] == '\n') gotstring = 0;
+            if(written > 0) addtoreadidx(written);
+        }else{ // head after tail - two chunks
+            int first = USARTRXDMABUFSZ - dma_read_idx;
+            int written = RB_write(&RxRB, &dmarxbuf[dma_read_idx], first);
+            if(written != first){ // could write only part - just increase read index
+                if(written > 0) addtoreadidx(written);
+            }else{
+                dma_read_idx = 0;
+                int last = available - first;
+                written = RB_write(&RxRB, dmarxbuf, last);
+                if(written == last && dmarxbuf[last-1] == '\n') gotstring = 0;
+                if(written > 0) addtoreadidx(written);
+            }
+        }
+    }
+    return flags;
+}
+
+char *usart_getline(){
+    static char buff[MAX_INPLEN];
+    int l = RB_datalento(&RxRB, '\n');
+    if(l < 1){
+        l = RB_datalen(&RxRB); // Rx ringbuffer could be near overflow but without '\n'
+        if(l < MAX_INPLEN-1) return NULL; // allow to wait for last symbols
+    }
+    if(l > MAX_INPLEN-1){ // overflow -> read at least part of the string
+        l = MAX_INPLEN-1;
+    }
+    if(l != RB_read(&RxRB, (uint8_t*)buff, l)) return NULL;
+    buff[l] = 0; // return with '\n' at end of line (so user can detect non-finished overflowed lines)
+    return buff;
+}
+
+// interrupt by '\n'
+static void usart_isr(){
+    if(USARTx->ISR & USART_ISR_CMF){ // got '\n' @ USARTx
+        gotstring = true;
+    }
+    USARTx->ICR = 0xffffffff; // clear all flags
+}
+
+static void dmarx_isr(){
+    volatile uint32_t isr = DMAx->ISR;
+    if(isr & DMARXEF){ // error
+        reinit_rx_dma();
+        curflags.rxovrfl = 1;
+    }
+    DMAx->IFCR = DMARXEF; // clear all flags
+}
+
+static void dmatx_isr(){
+    volatile uint32_t isr = DMAx->ISR;
+    if(isr & DMATXTCF) txrdy = true;
+    if(isr & DMATXEF) curflags.txerr = 1;
+    DMAx->IFCR = DMATXTCF | DMATXEF; // clear all flags
+}

G4:G431/CORDIC/usart.h

@@ -0,0 +1,49 @@
+/*
+ * This file is part of the cordic project.
+ * Copyright 2026 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+// maximal length of input string (including '\n' and terminating zero)
+#define MAX_INPLEN      (128)
+// Rx/Tx ring buffer size
+#define USARTTXBUFSZ    (512)
+#define USARTRXBUFSZ    (512)
+// Rx/Tx DMA buffer size
+#define USARTTXDMABUFSZ (256)
+#define USARTRXDMABUFSZ (256)
+
+// blocking timeout - not more than 5ms
+#define USARTBLKTMOUT   (5)
+// send buffer each 10ms
+#define USARTSENDTMOUT  (10)
+
+typedef union{
+    struct{
+        uint8_t txerr       : 1; // transmit error
+        uint8_t rxovrfl     : 1; // receive buffer overflow
+    };
+    uint8_t all;
+} USART_flags_t;
+
+void usart_setup(uint32_t speed);
+int usart_send(const char *str, int len);
+char *usart_getline();
+int usart_sendstr(const char *str);
+USART_flags_t usart_process();

G4:G431/CORDIC/version.inc

@@ -0,0 +1,2 @@
+#define BUILD_NUMBER "48"
+#define BUILD_DATE "2026-08-12"

makefile.stm32

@@ -49,11 +49,10 @@ LIB_DIR		:= $(INC_DIR)/ld
 
 ###############################################################################
 # C flags
-CFLAGS		+= -D__thumb2__=1 -MD 
-CFLAGS		+= -Wall -Wextra -Wshadow -Wdouble-promotion
-CFLAGS		+= -fshort-enums -ffunction-sections -fdata-sections
-#CFLAGS		+= -fno-common -fno-stack-protector
-CFLAGS		+=  $(ARCH_FLAGS)
+FLAGS       := -D__thumb2__=1 -MD -Wall -Wextra -Wshadow -Wdouble-promotion -fshort-enums -ffunction-sections -fdata-sections
+# -fno-common -fno-stack-protector
+CFLAGS		+= $(FLAGS)  $(ARCH_FLAGS)
+CPPFLAGS	+= $(FLAGS)  $(ARCH_FLAGS)
 
 ###############################################################################
 # Linker flags
@@ -130,6 +129,8 @@ $(VERSION_FILE): *.[ch]
 	@sed -i "s/#define BUILDNO.*/#define BUILDNO $(NEXTVER)/" $(VERSION_FILE)
 	@sed -i "s/#define BUILD_DATE.*/#define BUILD_DATE \"$(BUILDDATE)\"/" $(VERSION_FILE)
 
+$(OBJDIR)/commproto.o: commproto.cpp $(VERSION_FILE)
+
 $(OBJDIR)/proto.o: proto.c $(VERSION_FILE)
 
 $(OBJDIR)/usb_dev.o: CFLAGS := $(filter-out -flto,$(CFLAGS)) -fno-lto
@@ -140,7 +141,7 @@ $(OBJDIR)/%.o: %.c
 
 $(OBJDIR)/%.o: %.cpp
 	@echo "  C++     $<"
-	$(CPP) -c $(CFLAGS) -std=c++11 -fno-exceptions -fno-rtti -Wl,--trace-symbol=_sbrk $(DEFS) $(INCLUDE) -o $@ -c $<
+	$(CPP) -c  $(CPPFLAGS) -fno-exceptions -fno-rtti -Wl,--trace-symbol=_sbrk $(DEFS) $(INCLUDE) -o $@ -c $<
 
 $(BIN): $(ELF)
 	@echo "  OBJCOPY $(BIN)"