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simplest servo

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This commit is contained in:
Edward Emelianov
2026-07-28 23:17:03 +03:00
parent f6178a8b84
commit 2b4a9cbd84
23 changed files with 1566 additions and 0 deletions
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12
G4:G431/Servo/Makefile Normal file
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BINARY := servo
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
include ../makefile.g4
include ../../makefile.stm32

318
G4:G431/Servo/commproto.cpp Normal file
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/*
* This file is part of the as3935 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 <stm32g4.h>
#include "commproto.h"
//#include "flash.h"
#include "hardware.h"
#include "servo.h"
#include "strfunc.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(mcureset, "reset MCU") \
COMMAND(servo, "get/set servoN value, mks (from " STR(SG90_MINPULSE) " to " STR(SG90_MAXPULSE) ")") \
COMMAND(servopos, "get/set servoN target position with given speed") \
COMMAND(servospeed, "get/set servoN speed, mks per 20ms (1.." STR(SG90_MAXSPEED) ")") \
COMMAND(time, "show current time (ms)") \
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)
/**
* @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 && parval){
*parval = I32;
return true;
}
return false;
}
static errcodes_t cmd_servo(const char *cmd, char *args){
int32_t val, parno;
if(argsvals(args, &parno, &val)){ // setter
if(parno < 0 || parno >= SERVO_AMOUNT) return ERR_BADPAR;
if(!set_servo((uint8_t)parno, (uint16_t)val)) return ERR_BADVAL;
}
uint16_t curval;
if(!get_servo((uint8_t)parno, &curval)) return ERR_BADPAR;
CMDEQP(parno);
SEND(u2str(curval));
SEND("\n");
return ERR_AMOUNT;
}
static errcodes_t cmd_servopos(const char *cmd, char *args){
int32_t val, parno;
if(argsvals(args, &parno, &val)){ // setter
if(parno < 0 || parno >= SERVO_AMOUNT) return ERR_BADPAR;
if(!servo_set_tagpos((uint8_t)parno, (uint16_t)val)) return ERR_BADVAL;
}
uint16_t curval;
if(!servo_get_tagpos((uint8_t)parno, &curval)) return ERR_BADPAR;
CMDEQP(parno);
SEND(u2str(curval));
SEND("\n");
return ERR_AMOUNT;
}
static errcodes_t cmd_servospeed(const char *cmd, char *args){
int32_t val, parno;
if(argsvals(args, &parno, &val)){ // setter
if(parno < 0 || parno >= SERVO_AMOUNT) return ERR_BADPAR;
if(!servo_set_speed((uint8_t)parno, (uint16_t)val)) return ERR_BADVAL;
}
uint16_t curval;
if(!servo_get_speed((uint8_t)parno, &curval)) return ERR_BADPAR;
CMDEQP(parno);
SEND(u2str(curval));
SEND("\n");
return ERR_AMOUNT;
}
static errcodes_t cmd_time(const char *cmd, char*){
CMDEQ();
SEND(u2str(Tms)); SEND("\n");
return ERR_AMOUNT;
}
static errcodes_t cmd_mcureset(const char*, char*){
NVIC_SystemReset();
return ERR_CANTRUN; // never reached
}
#if 0
static errcodes_t cmd_saveconf(const char*, char*){
if(store_userconf()) return ERR_CANTRUN;
return ERR_OK;
}
static errcodes_t cmd_eraseflash(const char*, char*){
if(erase_storage(-1)) return ERR_CANTRUN;
return ERR_OK;
}
static errcodes_t cmd_readconf(const char*, char* args){
int32_t CHno = -1;
splitargs(args, &CHno);
if(CHno < 0 || CHno >= SENSORS_AMOUNT) return ERR_BADPAR;
as3935_channel = static_cast<uint8_t>(CHno);
uint8_t par;
if(!as3935_get_gain(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].AFE_GB = par;
if(!as3935_get_wdthres(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].WDTH = par;
if(!as3935_get_nflev(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].NF_LEV = par;
if(!as3935_get_srej(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].SREJ = par;
if(!as3935_get_minnumlig(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].MIN_NUM_LIG = par;
if(!as3935_get_maskdist(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].MASK_DIST = par;
if(!as3935_get_lco_fdiv(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].LCO_FDIV = par;
if(!as3935_get_tuncap(&par)) return ERR_CANTRUN;
the_conf.spars[CHno].TUN_CAP = par;
return ERR_OK;
}
static void showpar(const char *par, uint8_t n, uint8_t v){
char c[2];
c[0] = '0' + n; c[1] = 0;
SEND(par); SEND(c); SEND(EQ);
SEND(u2str(v));
}
static errcodes_t cmd_dumpconf(const char*, char*){
SEND("userconf_sz="); SEND(u2str(the_conf.userconf_sz));
SEND("\ncurr_idx="); SEND(u2str(currentconfidx));
SEND("\ncapacity="); SEND(u2str(maxCnum-2));
cmd_setiface("\nsetiface", NULL);
cmd_restonstart("restonstart", NULL);
for(int i = 0; i < SENSORS_AMOUNT; ++i){
showpar("gain", i, the_conf.spars[i].AFE_GB);
showpar("\nlco_fdiv", i, the_conf.spars[i].LCO_FDIV);
showpar("\nmaskdist", i, the_conf.spars[i].MASK_DIST);
showpar("\nminnumlig", i, the_conf.spars[i].MIN_NUM_LIG);
showpar("\nnflev", i, the_conf.spars[i].NF_LEV);
showpar("\nsrej", i, the_conf.spars[i].SREJ);
showpar("\ntuncap", i, the_conf.spars[i].TUN_CAP);
showpar("\nwdthres", i, the_conf.spars[i].WDTH);
SEND("\n");
}
return ERR_AMOUNT;
}
#endif
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;
}
#if 0
/**
* @brief parse_hex_data - data parsing in case of `hex + text` input format
* @param input - input string
* @param output - output data
* @param max_len - length of `output`
* @return amount of parsed bytes or -1 in case of overflow or error
*/
static int parse_hex_data(char *input, uint8_t *output, int max_len){
if(!input || !*input || !output || max_len < 1) return 0;
char *p = input;
int out_idx = 0;
while(*p && out_idx < max_len){
while(*p == ' ' || *p == ',') ++p; // omit spaces and commas as delimeters
if(*p == '\0') break; // EOL
if(*p == '"'){ // TEXT (start/end)
++p;
while(*p && *p != '"'){
if(out_idx >= max_len) return -1;
output[out_idx++] = *p++;
}
if(*p == '"'){
++p; // go to next symbol after closing quotation mark
}else return -1; // no closing
}else{ // HEX number
char *start = p;
while(*p && *p != ' ' && *p != ',' && *p != '"') ++p;
char saved = *p;
*p = '\0'; // temporarily for `gethex`
uint32_t val;
const char *end = gethex(start, &val);
if(end != p || val > 0xFF){ // not a hex number or have more than 2 symbols
*p = saved;
return -1;
}
*p = saved;
output[out_idx++] = (uint8_t)val;
}
}
return out_idx;
}
#endif
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;
}

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G4:G431/Servo/commproto.h Normal file
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/*
* This file is part of the servo 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);

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G4:G431/Servo/hardware.c Normal file
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/*
* This file is part of the usart 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"
#include "servo.h"
volatile uint32_t Tms = 0;
volatile bool tim_triggered[SERVO_AMOUNT];
/* Called when systick fires */
void sys_tick_handler(){
++Tms;
}
// try to set servo; if wrong return false
bool set_servo(uint8_t N, uint16_t val){
if(N >= SERVO_AMOUNT) return false;
if(val < SG90_MINPULSE || val > SG90_MAXPULSE) return false;
volatile uint32_t *CCR = &(TIM3->CCR1);
CCR[N] = val;
return true;
}
bool get_servo(uint8_t N, uint16_t *val){
if(N >= SERVO_AMOUNT) return false;
volatile uint32_t *CCR = &(TIM3->CCR1);
if(val) *val = CCR[N];
return true;
}
static void tim3_setup(){
RCC->APB1ENR1 |= RCC_APB1ENR1_TIM3EN;
__DSB();
// PWM mode 1 (active -> inactive) on all three channels; preload enabled
TIM3->CCMR1 = TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1M_1 |
TIM_CCMR1_OC2M_2 | TIM_CCMR1_OC2M_1 |
TIM_CCMR1_OC1PE | TIM_CCMR1_OC2PE;
TIM3->CCMR2 = TIM_CCMR2_OC3M_2 | TIM_CCMR2_OC3M_1 |
TIM_CCMR2_OC4M_2 | TIM_CCMR2_OC4M_1 |
TIM_CCMR2_OC3PE | TIM_CCMR2_OC4PE;
// frequency
TIM3->PSC = 169; // 1MHz -> 1us per tick
// ARR for PWM
TIM3->ARR = 19999; // 20ms, 50Hz
// CCRx - minimal position
TIM3->CCR1 = TIM3->CCR2 = TIM3->CCR3 = TIM3->CCR4 = SG90_MINPULSE;
// enable CCx interrupts
TIM3->DIER = TIM_DIER_CC1IE | TIM_DIER_CC2IE | TIM_DIER_CC3IE | TIM_DIER_CC4IE;
// enable main output
//TIM3->BDTR |= TIM_BDTR_MOE;
// enable PWM output
TIM3->CCER = TIM_CCER_CC1E | TIM_CCER_CC2E |TIM_CCER_CC3E | TIM_CCER_CC4E;
// enable timer & ARR buffering
TIM3->CR1 |= TIM_CR1_CEN | TIM_CR1_ARPE;
// update buffers
TIM3->EGR = TIM_EGR_UG;
// and enable interrupt
NVIC_EnableIRQ(TIM3_IRQn);
}
// TIM3 channels: 1 - PA6 (AF2), 2 - PA7 (AF2), 3 - PB0 (AF2), 4 - PB1 (AF2)
void gpio_setup(){
RCC->AHB2ENR = RCC_AHB2ENR_GPIOAEN | RCC_AHB2ENR_GPIOBEN | RCC_AHB2ENR_GPIOCEN;
__DSB(); // Data Synchronization Barrier - wait until data will be really written to AHB2ENR
// set PC6 as push-pull output, PC13 is pulldown input, other as default (AIN)
GPIOC->MODER = (0xffffffff & ~(GPIO_MODER_MODE6 | GPIO_MODER_MODE13)) | MODER_O(6) | MODER_I(13);
GPIOC->PUPDR = PUPD_PD(13); // pulldown
GPIOC->OTYPER = OTYPER_PP(6); // push-pull (default)
// PA9 (Tx) and PA10 (Rx) (don't forget about SWDIO)
GPIOA->MODER = (0xabffffff & ~(GPIO_MODER_MODE6 | GPIO_MODER_MODE7 | GPIO_MODER_MODE9 | GPIO_MODER_MODE10)) |
MODER_AF(6) | MODER_AF(7) | MODER_AF(9) | MODER_AF(10);
GPIOA->AFR[0] = AFRf(2, 6) | AFRf(2, 7);
GPIOA->AFR[1] = AFRf(7, 9) | AFRf(7, 10); // SWDIO is 0 by default; USART1 is AF7
GPIOB->MODER = (0xffffffff & ~(GPIO_MODER_MODE0 | GPIO_MODER_MODE1)) |
MODER_AF(0) | MODER_AF(1);
GPIOB->AFR[0] = AFRf(2, 0) | AFRf(2, 1);
// count milliseconds
SysTick_Config(SysFreq / 1000); // arg should be < 0xffffff
tim3_setup();
}
// update event flags
void tim3_isr(){
if(TIM3->SR & TIM_SR_CC1IF) tim_triggered[0] = true;
if(TIM3->SR & TIM_SR_CC2IF) tim_triggered[1] = true;
if(TIM3->SR & TIM_SR_CC3IF) tim_triggered[2] = true;
if(TIM3->SR & TIM_SR_CC4IF) tim_triggered[3] = true;
TIM3->SR = 0;
}

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G4:G431/Servo/hardware.h Normal file
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/*
* This file is part of the usart 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
extern volatile uint32_t Tms;
extern volatile bool tim_triggered[SERVO_AMOUNT];
void gpio_setup();
bool set_servo(uint8_t N, uint16_t val);
bool get_servo(uint8_t N, uint16_t *val);

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G4:G431/Servo/main.c Normal file
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/*
* This file is part of the blink 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 "servo.h"
#include "usart.h"
// 40ms for debouncing
#define TDEBOUNCE (40)
int main(void){
StartHSE();
gpio_setup();
usart_setup(115200);
bool pressed = false;
uint32_t Tblink = 0, Tkey = 0; // blink and key pressed time
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);
}
process_servo();
if(Tms - Tblink > 499){
LED_TOGG();
Tblink = Tms;
}
if(KEY_PRESSED()){
if(!pressed){ // new event
pressed = true;
usart_sendstr("Key pressed\n");
}
Tkey = Tms;
}else{ // key released
if(pressed && (Tms - Tkey) > TDEBOUNCE){ // wait for debounce
pressed = false;
usart_sendstr("Key released\n");
}
}
}
}

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G4:G431/Servo/openocd.cfg Normal file
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set FLASH_SIZE 0x20000
source [find interface/stlink-v2-1.cfg]
source [find target/stm32g4x.cfg]

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G4:G431/Servo/ringbuffer.c Normal file
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/*
* 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;
}

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/*
* 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);

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/*
* This file is part of the servo 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 <stdint.h>
#include "hardware.h"
#include "servo.h"
static uint16_t servo_tagpos[SERVO_AMOUNT] = {SG90_MIDPULSE, SG90_MIDPULSE, SG90_MIDPULSE, SG90_MIDPULSE};
static uint16_t servo_speed[SERVO_AMOUNT] = {0, 0, 0, 0};
void process_servo(){
for(uint8_t i = 0; i < SERVO_AMOUNT; ++i){
uint16_t curpos;
if(!get_servo(i, &curpos) || !tim_triggered[i]) continue;
tim_triggered[i] = false;
if(servo_tagpos[i] == curpos || servo_speed[i] < 1) continue;
int32_t newpos = curpos;
if(servo_tagpos[i] > curpos){
newpos += servo_speed[i];
if(newpos > servo_tagpos[i]) newpos = servo_tagpos[i];
}else{
newpos -= servo_speed[i];
if(newpos < servo_tagpos[i]) newpos = servo_tagpos[i];
}
set_servo(i, (uint16_t) newpos);
}
}
// set speed in steps per tick
bool servo_set_speed(uint8_t N, uint16_t s){
if(N >= SERVO_AMOUNT) return false;
if(s < 1 || s > SG90_MAXSPEED) return false;
servo_speed[N] = s;
return true;
}
bool servo_get_speed(uint8_t N, uint16_t *s){
if(N >= SERVO_AMOUNT) return false;
if(s) *s = servo_speed[N];
return true;
}
bool servo_set_tagpos(uint8_t N, uint16_t pos){
if(N >= SERVO_AMOUNT) return false;
if(pos < SG90_MINPULSE || pos > SG90_MAXPULSE) return false;
servo_tagpos[N] = pos;
return true;
}
bool servo_get_tagpos(uint8_t N, uint16_t *pos){
if(N >= SERVO_AMOUNT) return false;
if(pos) *pos = servo_tagpos[N];
return true;
}

1
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-std=c23

3
G4:G431/Servo/servo.config Normal file
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#define EBUG
#define STM32G4
#define STM32G431xx

1
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[General]

1
G4:G431/Servo/servo.cxxflags Normal file
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@@ -0,0 +1 @@
-std=c++23

13
G4:G431/Servo/servo.files Normal file
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commproto.cpp
commproto.h
hardware.c
hardware.h
main.c
ringbuffer.c
ringbuffer.h
servo.c
servo.h
strfunc.c
strfunc.h
usart.c
usart.h

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/*
* This file is part of the servo 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
// minimal and maximal pulse length for SG90
#define SG90_MINPULSE 700
#define SG90_MAXPULSE 2100
#define SG90_MIDPULSE ((SG90_MINPULSE+SG90_MAXPULSE)/2)
#define SG90_AMPL (SG90_MAXPULSE-SG90_MINPULSE)
// maximal speed: 0.1s (5 ticks) per 60degr (1/3 of range): (SG90_AMPL/15)
#define SG90_MAXSPEED 93
void process_servo();
bool servo_set_speed(uint8_t N, uint16_t s);
bool servo_get_speed(uint8_t N, uint16_t *s);
bool servo_set_tagpos(uint8_t N, uint16_t pos);
bool servo_get_tagpos(uint8_t N, uint16_t *pos);

4
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.
../inc
../inc/Fx
../inc/cm

265
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/*
* This file is part of the encoders project.
* 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 <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;
}

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/*
* This file is part of the encoders project.
* 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>
void hexdump(int (*sendfun)(const char*), uint8_t *arr, uint16_t len);
char *u2str(uint32_t val);
char *i2str(int32_t i);
char *uhex2str(uint32_t val);
char *gethex(const char *buf, uint32_t *N);
char *getnum(char *txt, uint32_t *N);
char *omit_spaces(char *buf);
char *getint(char *txt, int32_t *I);

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/*
* This file is part of the test 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
}

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G4:G431/Servo/usart.h Normal file
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/*
* This file is part of the test 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();

2
G4:G431/Servo/version.inc Normal file
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#define BUILD_NUMBER "9"
#define BUILD_DATE "2026-07-28"