diff --git a/F1:F103/AS3935-lightning/as3935.bin b/F1:F103/AS3935-lightning/as3935.bin
index 69e28a7..255e37e 100755
Binary files a/F1:F103/AS3935-lightning/as3935.bin and b/F1:F103/AS3935-lightning/as3935.bin differ
diff --git a/F1:F103/AS3935-lightning/as3935.c b/F1:F103/AS3935-lightning/as3935.c
index 6615d01..5513073 100644
--- a/F1:F103/AS3935-lightning/as3935.c
+++ b/F1:F103/AS3935-lightning/as3935.c
@@ -26,7 +26,7 @@
 extern uint32_t Tms;
 
 // read one register
-static int as3935_read(uint8_t reg, uint8_t *data){
+int as3935_read(uint8_t reg, uint8_t *data){
     uint8_t word[2];
     word[0] = MODE_READ | (reg & MODE_MASK);
     word[1] = 0;
@@ -35,7 +35,7 @@ static int as3935_read(uint8_t reg, uint8_t *data){
     return TRUE;
 }
 
-static int as3935_write(uint8_t reg, uint8_t data){
+int as3935_write(uint8_t reg, uint8_t data){
     uint8_t word[2];
     word[0] = MODE_WRITE | (reg & MODE_MASK);
     word[1] = data;
@@ -100,33 +100,26 @@ int as3935_gain(uint8_t n){
 }
 #endif
 
-#include "usb_dev.h"
-#include "strfunc.h"
-// starting calibration
+// calibrate RCO
 int as3935_calib_rco(){
     t_tun_disp t;
-    USB_sendstr("1\n");
     if(!as3935_read(TUN_DISP, &t.u8)) return FALSE;
-    USB_sendstr("2\n");
     if(!as3935_write(CALIB_RCO, DIRECT_COMMAND)) return FALSE;
-    USB_sendstr("3\n");
     t.DISP_LCO = t.DISP_TRCO = 0;
     t.DISP_SRCO = 1;
     if(!as3935_write(TUN_DISP, t.u8)) return FALSE;
-    USB_sendstr("4\n");
     uint32_t Tstart = Tms;
     while(Tms - Tstart < 3) IWDG->KR = IWDG_REFRESH; // sleep for ~2ms
     t.DISP_SRCO = 0;
-    USB_sendstr("5\n");
     if(!as3935_write(TUN_DISP, t.u8)) return FALSE;
-    while(Tms - Tstart < 300) IWDG->KR = IWDG_REFRESH; // sleep for ~2ms
+    return TRUE;
+}
+
+int as3935_get_calib(uint8_t *n){
     t_calib srco, trco;
-    USB_sendstr("6\n");
     if(!as3935_read(CALIB_TRCO, &trco.u8)) return FALSE;
-    USB_sendstr(uhex2str(trco.u8)); newline();
     if(!as3935_read(CALIB_SRCO, &srco.u8)) return FALSE;
-    USB_sendstr(uhex2str(srco.u8)); newline();
-    if(!srco.CALIB_DONE || !trco.CALIB_DONE) return FALSE;
+    *n = (!srco.CALIB_DONE || !trco.CALIB_DONE) ? 0 : 1;
     return TRUE;
 }
 
@@ -136,7 +129,7 @@ int as3935_wakeup(){
     if(!as3935_read(AFE_GAIN, &g.u8)) return FALSE;
     g.PWD = 0;
     if(!as3935_write(AFE_GAIN, g.u8)) return FALSE;
-    return as3935_calib_rco();
+    return TRUE;
 }
 
 // set amplifier gain
diff --git a/F1:F103/AS3935-lightning/as3935.creator.user b/F1:F103/AS3935-lightning/as3935.creator.user
index 22f7fa6..7d88ed0 100644
--- a/F1:F103/AS3935-lightning/as3935.creator.user
+++ b/F1:F103/AS3935-lightning/as3935.creator.user
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE QtCreatorProject>
-<!-- Written by QtCreator 19.0.0, 2026-04-11T00:25:21. -->
+<!-- Written by QtCreator 19.0.0, 2026-04-14T23:41:10. -->
 <qtcreator>
  <data>
   <variable>EnvironmentId</variable>
diff --git a/F1:F103/AS3935-lightning/as3935.h b/F1:F103/AS3935-lightning/as3935.h
index 876971c..79691cb 100644
--- a/F1:F103/AS3935-lightning/as3935.h
+++ b/F1:F103/AS3935-lightning/as3935.h
@@ -121,14 +121,18 @@ typedef union{
 // distance out of range
 #define DIST_OUT_OF_RANGE   (0x3f)
 
+int as3935_read(uint8_t reg, uint8_t *data);
+int as3935_write(uint8_t reg, uint8_t data);
+int as3935_wakeup();
+int as3935_get_calib(uint8_t *n);
+int as3935_calib_rco();
+
 int as3935_displco(uint8_t n);
 int as3935_get_displco(uint8_t *n);
 int as3935_tuncap(uint8_t n);
 int as3935_get_tuncap(uint8_t *n);
 int as3935_gain(uint8_t n);
 int as3935_get_gain(uint8_t *n);
-int as3935_wakeup();
-int as3935_calib_rco();
 //int as3935_set_gain(uint8_t g);
 int as3935_wdthres(uint8_t t);
 int as3935_get_wdthres(uint8_t *t);
diff --git a/F1:F103/AS3935-lightning/commproto.cpp b/F1:F103/AS3935-lightning/commproto.cpp
index 0810a3e..2dd4a61 100644
--- a/F1:F103/AS3935-lightning/commproto.cpp
+++ b/F1:F103/AS3935-lightning/commproto.cpp
@@ -24,6 +24,7 @@ extern "C"{
 #include "adc.h"
 #include "as3935.h"
 #include "commproto.h"
+#include "flash.h"
 #include "hardware.h"
 #include "spi.h"
 #include "strfunc.h"
@@ -36,10 +37,6 @@ extern volatile uint32_t Tms;
 
 static uint8_t curbuf[MAXSTRLEN];
 
-// COMMAND(dumpconf,   "dump global configuration")
-// COMMAND(eraseflash, "erase full flash storage")
-// COMMAND(readconf,   "re-read config from flash")
-// COMMAND(saveconf,   "save current user configuration into flash")
 // COMMAND(USART,      "Read USART data or send (USART=hex)")
 
 // list of all commands and handlers
@@ -47,21 +44,28 @@ static uint8_t curbuf[MAXSTRLEN];
     COMMAND(clearstat,  "clear amount of lightnings for last 15 min") \
     COMMAND(displco,    "display on LCO: 0- nothing, 1- TRCO, 2- SRCO, 3- LCO") \
     COMMAND(distance,   "distance to lightning, km") \
+    COMMAND(dumpconf,   "dump current configuration") \
     COMMAND(energy,     "energy of last lightning") \
+    COMMAND(eraseflash, "erase full flash storage") \
     COMMAND(gain,       "change sensor's gain (0..1f)") \
     COMMAND(help,       "show this help") \
     COMMAND(intcode,    "last interrupt code") \
+    COMMAND(iscalib,    "check if sensor x calibrated") \
     COMMAND(lco_fdiv,   "set Fdiv of antenna LCO") \
     COMMAND(maskdist,   "mask (1) or unmask (0) disturber") \
     COMMAND(mcutemp,    "get MCU temperature (degC*10)") \
     COMMAND(mcureset,   "reset MCU") \
     COMMAND(minnumlig,  "ninimal lightnings number (0..2)") \
     COMMAND(nflev,      "noice floor level (0..7)") \
+    COMMAND(readconf,   "read configuration from given sensor") \
     COMMAND(resetdef,   "reset sensor to defaults") \
+    COMMAND(restonstart,"restore sensors configuration on start") \
+    COMMAND(saveconf,   "save current configuration into flash") \
+    COMMAND(setiface,   "set USB interface name (max 16 symbols)") \
     COMMAND(SPI,        "transfer SPI data: SPIx=data (hex)") \
     COMMAND(srej,       "spike rejection (0..15)") \
     COMMAND(time,       "show current time (ms)") \
-    COMMAND(tuncap,     "set 'tune capasitors' to given value") \
+    COMMAND(tuncap,     "set 'tune capasitors' to given value (0..15)") \
     COMMAND(vdd,        "get approx Vdd value (V*100)") \
     COMMAND(wakeup,     "wake-up given sensor and make its calibration") \
     COMMAND(wdthres,    "watchdog threshold (0..15)" )
@@ -93,7 +97,7 @@ static const char* errtxt[ERR_AMOUNT] = {
     [ERR_OVERFLOW]  = "OVERFLOW\n",
 };
 
-static const char *EQ = " = "; // equal sign for getters
+const char *EQ = " = "; // equal sign for getters
 
 // send `command = `
 #define CMDEQ()   do{SEND(cmd); SEND(EQ);}while(0)
@@ -141,47 +145,128 @@ static bool argsvals(char *args, int32_t *parno, int32_t *parval){
     return false;
 }
 
-static errcodes_t cmd_time(const char *cmd, char _U_ *args){
+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 _U_ *cmd, char _U_ *args){
+static errcodes_t cmd_mcureset(const char*, char*){
     NVIC_SystemReset();
     return ERR_CANTRUN; // never reached
 }
-#if 0
-static errcodes_t cmd_readconf(const char _U_ *cmd, char _U_ *args){
-    flashstorage_init();
-    return ERR_OK;
-}
 
-static errcodes_t cmd_saveconf(const char _U_ *cmd, char _U_ *args){
+static errcodes_t cmd_saveconf(const char*, char*){
     if(store_userconf()) return ERR_CANTRUN;
     return ERR_OK;
 }
 
-static errcodes_t cmd_eraseflash(const char _U_ *cmd, char _U_ *args){
-    if(erase_storage()) return ERR_CANTRUN;
+static errcodes_t cmd_eraseflash(const char*, char*){
+    if(erase_storage(-1)) return ERR_CANTRUN;
     return ERR_OK;
 }
-#endif
 
+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 errcodes_t cmd_mcutemp(const char *cmd, char _U_ *args){
+static errcodes_t cmd_setiface(const char* cmd, char* args){
+    char *ifname = splitargs(args, NULL);
+    if(ifname){ // setter
+        int l = strlen(ifname);
+        if(l > MAX_IINTERFACE_SZ) return ERR_BADPAR; // too long
+        the_conf.iIlength = (uint8_t) l * 2;
+        char *ptr = (char*)the_conf.iInterface;
+        for(int i = 0; i < l; ++i){
+            *ptr++ = *ifname++;
+            *ptr++ = 0;
+        }
+    }
+    // getter
+    CMDEQ();
+    int l = the_conf.iIlength / 2;
+    char *ptr = (char*)the_conf.iInterface;
+    for(int i = 0; i < l; ++i){
+        SEND(ptr); // next is always zero
+        ptr += 2;
+    }
+    SEND("\n");
+    return ERR_AMOUNT;
+}
+
+static errcodes_t cmd_restonstart(const char* cmd, char* args){
+    int32_t val;
+    if(argsvals(args, NULL, &val)){ // setter
+        if(!val) the_conf.flags.restore = 0;
+        else the_conf.flags.restore = 1;
+    }
+    CMDEQ();
+    SEND(u2str(the_conf.flags.restore));
+    SEND("\n");
+    return ERR_AMOUNT;
+}
+
+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;
+}
+
+static errcodes_t cmd_mcutemp(const char *cmd, char*){
     CMDEQ();
     SEND(i2str(getMCUtemp())); SEND("\n");
     return ERR_AMOUNT;
 }
 
-static errcodes_t cmd_vdd(const char *cmd, char _U_ *args){
+static errcodes_t cmd_vdd(const char *cmd, char*){
     CMDEQ();
     SEND(u2str(getVdd())); SEND("\n");
     return ERR_AMOUNT;
 }
 
-static errcodes_t cmd_help(const char _U_ *cmd, char _U_ *args){
+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);
@@ -194,9 +279,8 @@ static errcodes_t cmd_help(const char _U_ *cmd, char _U_ *args){
 static errcodes_t senscmd8(int32_t CHno, int (*cmd)(uint8_t), int32_t arg){
     if(CHno < 0 || CHno >= SENSORS_AMOUNT) return ERR_BADPAR;
     uint8_t par = static_cast<uint8_t>(arg);
-    CS(CHno);
+    as3935_channel = static_cast<uint8_t>(CHno);
     int ans = cmd(par);
-    CS_OFF();
     if(ans) return ERR_OK;
     return ERR_CANTRUN;
 }
@@ -204,9 +288,8 @@ static errcodes_t senscmd8(int32_t CHno, int (*cmd)(uint8_t), int32_t arg){
 static errcodes_t getta(const char *cmd, int32_t CHno, int (*fn)(uint8_t*)){
     if(CHno < 0 || CHno >= SENSORS_AMOUNT) return ERR_BADPAR;
     uint8_t par;
-    CS(CHno);
+    as3935_channel = static_cast<uint8_t>(CHno);
     int ans = fn(&par);
-    CS_OFF();
     if(!ans) return ERR_CANTRUN;
     CMDEQP(CHno); SEND(u2str(par)); SEND("\n");
     return ERR_AMOUNT;
@@ -214,9 +297,8 @@ static errcodes_t getta(const char *cmd, int32_t CHno, int (*fn)(uint8_t*)){
 
 static errcodes_t senscmd(int32_t CHno, int (*cmd)()){
     if(CHno < 0 || CHno >= SENSORS_AMOUNT) return ERR_BADPAR;
-    CS(CHno);
+    as3935_channel = static_cast<uint8_t>(CHno);
     int ans = cmd();
-    CS_OFF();
     if(ans) return ERR_OK;
     return ERR_CANTRUN;
 }
@@ -249,7 +331,6 @@ AS3935_FN8(srej)
 AS3935_FN8(minnumlig)
 AS3935_FN8(maskdist)
 AS3935_FN8(lco_fdiv)
-AS3935_FN(wakeup)
 AS3935_FN(clearstat)
 AS3935_FN(resetdef)
 
@@ -258,7 +339,8 @@ static errcodes_t cmd_ ## nm(const char* cmd, char* args){ \
     int32_t CHno = -1; uint8_t par;\
     splitargs(args, &CHno); \
     if(CHno < 0 || CHno >= SENSORS_AMOUNT) return ERR_BADPAR; \
-    CS(CHno); int ans = as3935_ ## nm(&par); CS_OFF(); \
+    as3935_channel = static_cast<uint8_t>(CHno); \
+    int ans = as3935_ ## nm(&par); \
     if(!ans) return ERR_CANTRUN; \
     CMDEQP(CHno); SEND(u2str(par)); SEND("\n"); \
     return ERR_AMOUNT; }
@@ -266,12 +348,27 @@ static errcodes_t cmd_ ## nm(const char* cmd, char* args){ \
 AS3935_GU8(intcode)
 AS3935_GU8(distance)
 
+static errcodes_t cmd_iscalib(const char* cmd, char* args){
+    int32_t CHno = -1;
+    splitargs(args, &CHno);
+    return getta(cmd, CHno, as3935_get_calib);
+}
+
+static errcodes_t cmd_wakeup(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);
+    if(!as3935_wakeup() || !as3935_calib_rco()) return ERR_CANTRUN;
+    return ERR_OK;
+}
+
 static errcodes_t cmd_energy(const char* cmd, char* args){
     int32_t CHno = -1; uint32_t par;
     splitargs(args, &CHno);
     if(CHno < 0 || CHno >= SENSORS_AMOUNT) return ERR_BADPAR;
-    CS(CHno); int ans = as3935_energy(&par); CS_OFF();
-    if(!ans) return ERR_CANTRUN;
+    as3935_channel = static_cast<uint8_t>(CHno);
+    if(!as3935_energy(&par)) return ERR_CANTRUN;
     CMDEQP(CHno); SEND(u2str(par)); SEND("\n");
     return ERR_AMOUNT;
 }
@@ -317,7 +414,7 @@ static int parse_hex_data(char *input, uint8_t *output, int max_len){
     return out_idx;
 }
 
-static errcodes_t cmd_SPI(const char _U_ *cmd, char *args){
+static errcodes_t cmd_SPI(const char* cmd, char *args){
     if(!args) return ERR_BADVAL;
     if(!(SPI1->CR1 & SPI_CR1_SPE)) return ERR_CANTRUN;
     int32_t CHno;
@@ -326,9 +423,8 @@ static errcodes_t cmd_SPI(const char _U_ *cmd, char *args){
     if(CHno < 0 || CHno >= SENSORS_AMOUNT) return ERR_BADPAR;
     int len = parse_hex_data(setter, curbuf, MAXSTRLEN);
     if(len <= 0) return ERR_BADVAL;
-    CS(CHno);
+    as3935_channel = static_cast<uint8_t>(CHno);
     uint8_t ret = SPI_transmit(curbuf, len);
-    CS_OFF();
     if(!ret) return ERR_BUSY;
     CMDEQP(CHno);
     if(len > 8) SEND("\n");
@@ -359,3 +455,13 @@ const char *parse_cmd(int (*sendfun)(const char *), char *str){
     if(ecode < ERR_AMOUNT) return errtxt[ecode];
     return NULL;
 }
+
+// show lightning information
+void lightning_info(int (*sendfun)(const char*), uint8_t CHno){
+    if(!sendfun || CHno >= SENSORS_AMOUNT) return;
+    char c[2];
+    c[0] = '0' + CHno; c[1] = 0;
+    SEND = sendfun;
+    cmd_energy("energy", c);
+    cmd_distance("distance", c);
+}
diff --git a/F1:F103/AS3935-lightning/commproto.h b/F1:F103/AS3935-lightning/commproto.h
index 6e585dd..2efe1ce 100644
--- a/F1:F103/AS3935-lightning/commproto.h
+++ b/F1:F103/AS3935-lightning/commproto.h
@@ -49,4 +49,6 @@ typedef enum{
 // maximal string length includint terminating zero
 #define MAXSTRLEN   256
 
+extern const char *EQ;
 const char *parse_cmd(int (*sendfun)(const char*), char *buf);
+void lightning_info(int (*sendfun)(const char*), uint8_t CHno);
diff --git a/F1:F103/AS3935-lightning/flash.c b/F1:F103/AS3935-lightning/flash.c
new file mode 100644
index 0000000..c0c406a
--- /dev/null
+++ b/F1:F103/AS3935-lightning/flash.c
@@ -0,0 +1,169 @@
+/*
+ * 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 <stm32f1.h>
+#include <string.h> // memcpy
+
+#include "flash.h"
+#include "strfunc.h"
+
+extern const uint32_t _BLOCKSIZE;
+extern const user_conf __varsstart;
+
+static const uint32_t FLASH_blocksize = (uint32_t)&_BLOCKSIZE;
+uint32_t maxCnum = 1024 / sizeof(user_conf); // can't use blocksize here
+
+static int write2flash(const void*, const void*, uint32_t);
+const user_conf *Flash_Data = (const user_conf *)(&__varsstart);
+user_conf the_conf = {
+    .userconf_sz = sizeof(user_conf),
+};
+
+int currentconfidx = -1; // index of current configuration
+
+/**
+ * @brief binarySearch - binary search in flash for last non-empty cell
+ *          any struct searched should have its sizeof() @ the first field!!!
+ * @param l - left index
+ * @param r - right index (should be @1 less than last index!)
+ * @param start - starting address
+ * @param stor_size - size of structure to search
+ * @return index of non-empty cell or -1
+ */
+static int binarySearch(int r, const uint8_t *start, int stor_size){
+    int l = 0;
+    while(r >= l){
+        int mid = l + (r - l) / 2;
+        const uint8_t *s = start + mid * stor_size;
+        if(*((const uint16_t*)s) == stor_size){
+            if(*((const uint16_t*)(s + stor_size)) == 0xffff){ // next is free
+                return mid;
+            }else{ // element is to the right
+                l = mid + 1;
+            }
+        }else{ // element is to the left
+            r = mid - 1;
+        }
+    }
+    return -1; // not found
+}
+
+/**
+ * @brief flashstorage_init - initialization of user conf storage
+ * run in once @ start
+ */
+void flashstorage_init(){
+    if(FLASH_SIZE > 0 && FLASH_SIZE < 20000){
+        uint32_t flsz = FLASH_SIZE * 1024; // size in bytes
+        flsz -= (uint32_t)(&__varsstart) - FLASH_BASE;
+        maxCnum = flsz / sizeof(user_conf);
+    }
+    // -1 if there's no data at all & flash is clear; maxnum-1 if flash is full
+    currentconfidx = binarySearch((int)maxCnum-2, (const uint8_t*)Flash_Data, sizeof(user_conf));
+    if(currentconfidx > -1){
+        memcpy(&the_conf, &Flash_Data[currentconfidx], sizeof(user_conf));
+    }
+}
+
+// store new configuration
+// @return 0 if all OK
+int store_userconf(){
+    // maxnum - 3 means that there always should be at least one empty record after last data
+    // for binarySearch() checking that there's nothing more after it!
+    if(currentconfidx > (int)maxCnum - 3){ // there's no more place
+        currentconfidx = 0;
+        if(erase_storage(-1)) return 1;
+    }else ++currentconfidx; // take next data position (0 - within first run after firmware flashing)
+    return write2flash((const void*)&Flash_Data[currentconfidx], &the_conf, sizeof(the_conf));
+}
+
+static int write2flash(const void *start, const void *wrdata, uint32_t stor_size){
+    int ret = 0;
+    if (FLASH->CR & FLASH_CR_LOCK){ // unloch flash
+        FLASH->KEYR = FLASH_KEY1;
+        FLASH->KEYR = FLASH_KEY2;
+    }
+    while (FLASH->SR & FLASH_SR_BSY)  IWDG->KR = IWDG_REFRESH;
+    FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPRTERR; // clear all flags
+    FLASH->CR |= FLASH_CR_PG;
+    const uint16_t *data = (const uint16_t*) wrdata;
+    volatile uint16_t *address = (volatile uint16_t*) start;
+    uint32_t i, count = (stor_size + 1) / 2;
+    for(i = 0; i < count; ++i){
+        *(volatile uint16_t*)(address + i) = data[i];
+        while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
+        if(*(volatile uint16_t*)(address + i) != data[i]){
+            ret = 1;
+            break;
+        }
+        if(FLASH->SR & FLASH_SR_PGERR){
+            ret = 1; // program error - meet not 0xffff
+            break;
+        }
+        FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPRTERR;
+    }
+    FLASH->CR &= ~(FLASH_CR_PG);
+    return ret;
+}
+
+// erase Nth page of flash storage (flash should be prepared!)
+static int erase_pageN(int N){
+    int ret = 0;
+    FLASH->AR = (uint32_t)Flash_Data + N*FLASH_blocksize;
+    FLASH->CR |= FLASH_CR_STRT;
+    while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
+    FLASH->SR = FLASH_SR_EOP;
+    if(FLASH->SR & FLASH_SR_WRPRTERR){ /* Check Write protection error */
+        ret = 1;
+        FLASH->SR = FLASH_SR_WRPRTERR; /* Clear the flag by software by writing it at 1*/
+    }
+    return ret;
+}
+
+// erase full storage (npage < 0) or its nth page; @return 0 if all OK
+int erase_storage(int npage){
+    int ret = 0;
+    uint32_t end = 1, start = 0, flsz = 0;
+    if(FLASH_SIZE > 0 && FLASH_SIZE < 20000){
+        flsz = FLASH_SIZE * 1024; // size in bytes
+        flsz -= (uint32_t)Flash_Data - FLASH_BASE;
+    }
+    end = flsz / FLASH_blocksize;
+    if(end == 0 || end >= FLASH_SIZE) return 1;
+    if(npage > -1){ // erase only one page
+        if((uint32_t)npage >= end) return 1;
+        start = npage;
+        end = start + 1;
+    }
+    if((FLASH->CR & FLASH_CR_LOCK) != 0){
+        FLASH->KEYR = FLASH_KEY1;
+        FLASH->KEYR = FLASH_KEY2;
+    }
+    while(FLASH->SR & FLASH_SR_BSY) IWDG->KR = IWDG_REFRESH;
+    FLASH->SR = FLASH_SR_EOP | FLASH_SR_PGERR | FLASH_SR_WRPRTERR;
+    FLASH->CR |= FLASH_CR_PER;
+    for(uint32_t i = start; i < end; ++i){
+        if(erase_pageN(i)){
+            ret = 1;
+            break;
+        }
+    }
+    FLASH->CR &= ~FLASH_CR_PER;
+    return ret;
+}
+
diff --git a/F1:F103/AS3935-lightning/flash.h b/F1:F103/AS3935-lightning/flash.h
new file mode 100644
index 0000000..e6b5eee
--- /dev/null
+++ b/F1:F103/AS3935-lightning/flash.h
@@ -0,0 +1,67 @@
+/*
+ * 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/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include "hardware.h" // for SENSORS_AMOUNT
+
+#define FLASH_SIZE_REG      ((uint32_t)0x1FFFF7E0)
+#define FLASH_SIZE          *((uint16_t*)FLASH_SIZE_REG)
+
+// maximal size (in letters) of iInterface for settings
+#define MAX_IINTERFACE_SZ   (16)
+
+typedef struct{
+    // t_afe_gain
+    uint8_t AFE_GB : 5;
+    // t_threshold
+    uint8_t WDTH : 4;
+    uint8_t NF_LEV : 3;
+    // t_lightning_reg
+    uint8_t SREJ : 4;
+    uint8_t MIN_NUM_LIG : 2;
+    // t_int_mask_ant
+    uint8_t MASK_DIST : 1;
+    uint8_t LCO_FDIV : 2;
+    // t_tun_disp
+    uint8_t TUN_CAP : 4;
+} sens_pars_t;
+
+typedef struct{
+    uint8_t restore : 1;   // restore sensors' parameters on start
+} flags_t;
+
+/*
+ * struct to save user configurations
+ */
+typedef struct __attribute__((packed, aligned(4))){
+    uint16_t userconf_sz;       // "magick number"
+    uint16_t iInterface[MAX_IINTERFACE_SZ]; // interface name
+    uint8_t iIlength;                       // length in symbols
+    sens_pars_t spars[SENSORS_AMOUNT];      // sensors' stored flags
+    flags_t flags;                          // common flags
+} user_conf;
+
+extern uint32_t maxCnum;
+extern user_conf the_conf;
+extern int currentconfidx;
+
+void flashstorage_init();
+int store_userconf();
+int erase_storage(int npage);
diff --git a/F1:F103/AS3935-lightning/main.c b/F1:F103/AS3935-lightning/main.c
index 077b30b..02c2848 100644
--- a/F1:F103/AS3935-lightning/main.c
+++ b/F1:F103/AS3935-lightning/main.c
@@ -17,8 +17,10 @@
  */
 
 #include "as3935.h"
+#include "flash.h"
 #include "hardware.h"
 #include "commproto.h"
+#include "flash.h"
 #include "spi.h"
 #include "strfunc.h"
 #include "usb_dev.h"
@@ -41,6 +43,7 @@ int main(){
     hw_setup();
     USBPU_OFF();
     SysTick_Config(72000);
+    flashstorage_init();
     USB_setup();
 #ifndef EBUG
     iwdg_setup();
@@ -48,10 +51,21 @@ int main(){
     //usart_setup();
     USBPU_ON();
     // wake-up all sensors and run auto-calibration
-    for(int ch = 0; ch < SENSORS_AMOUNT; ++ch){
-        CS(ch);
+    for(uint8_t ch = 0; ch < SENSORS_AMOUNT; ++ch){
+        as3935_channel = ch;
         as3935_wakeup();
-        CS_OFF();
+        as3935_calib_rco();
+        if(the_conf.flags.restore){
+            sens_pars_t *p = &the_conf.spars[ch];
+            as3935_gain(p->AFE_GB);
+            as3935_wdthres(p->WDTH);
+            as3935_nflev(p->NF_LEV);
+            as3935_srej(p->SREJ);
+            as3935_minnumlig(p->MIN_NUM_LIG);
+            as3935_maskdist(p->MASK_DIST);
+            as3935_lco_fdiv(p->LCO_FDIV);
+            as3935_tuncap(p->TUN_CAP);
+        }
     }
     while(1){
         IWDG->KR = IWDG_REFRESH; // refresh watchdog
@@ -65,24 +79,26 @@ int main(){
             const char *ans = parse_cmd(USB_sendstr, inbuff);
             if(ans) USB_sendstr(ans);
         }
-        for(int ch = 0; ch < SENSORS_AMOUNT; ++ch){
-            if(DISPLCO[ch] == DISPLCO_NOTHING) continue; // don't check IRQ in if it used as clock output
+        for(uint8_t ch = 0; ch < SENSORS_AMOUNT; ++ch){
+            if(DISPLCO[ch] != DISPLCO_NOTHING) continue; // don't check IRQ in if it used as clock output
             if(CHK_INT(ch)){
                 if(oldint[ch] == 0){
                     oldint[ch] = 1;
-                    USB_sendstr("INTERRUPT @ "); USB_putbyte('0'+ch); newline();
                     uint8_t code;
-                    CS(ch);
+                    as3935_channel = ch;
                     int result = as3935_intcode(&code);
-                    CS_OFF();
-                    if(!result) USB_sendstr("Can't get code\n");
-                    else{
-                        USB_sendstr("Code: ");
-                        switch(code){
-                        case INT_NH: USB_sendstr("Noice too high\n"); break;
-                        case INT_D: USB_sendstr("Disturber detected\n"); break;
-                        case INT_L: USB_sendstr("Lightning interrupt\n"); break;
-                        default: USB_sendstr("Unknown\n"); break;
+                    if(!result) USB_sendstr("CANTGET\n");
+                    else if(code){
+                        uint8_t savedcode = code;
+                        USB_sendstr("INTERRUPT"); USB_putbyte('0'+ch); USB_putbyte('=');
+                        const char *delim = NULL, *comma = ",";
+                        if(code & INT_NH){ USB_sendstr("NOICE"); delim = comma; code &= ~INT_NH; }
+                        if(code & INT_D){ USB_sendstr(delim); USB_sendstr("DISTURBER"); delim = comma; code &= ~INT_D; }
+                        if(code & INT_L){ USB_sendstr(delim); USB_sendstr("LIGHTNING"); code &= ~INT_L; }
+                        if(code) USB_sendstr(u2str(code));
+                        newline();
+                        if(savedcode == INT_L){ // clear lightning - show distance and power
+                            lightning_info(USB_sendstr, ch);
                         }
                     }
                 }
diff --git a/F1:F103/AS3935-lightning/spi.c b/F1:F103/AS3935-lightning/spi.c
index cf1be4b..4c0b84f 100644
--- a/F1:F103/AS3935-lightning/spi.c
+++ b/F1:F103/AS3935-lightning/spi.c
@@ -26,6 +26,7 @@
 static const uint32_t SPI_CR1 = SPI_CR1_MSTR | SPI_CR1_BR_2 | SPI_CR1_BR_0 | SPI_CR1_SSM | SPI_CR1_SSI | SPI_CR1_CPHA /* | SPI_CR1_CPOL*/;
 
 spiStatus SPI_status = SPI_NOTREADY;
+uint8_t as3935_channel = 0;
 
 void spi_setup(){
     // master, no slave select, BR=F/16, CPOL/CPHA - polarity.
@@ -46,6 +47,7 @@ volatile uint32_t wctr;
 uint8_t SPI_transmit(uint8_t *buf, uint8_t len){
     if(!buf || !len) return 0; // bad data format
     if(SPI_status != SPI_READY) return 0; // spi not ready to transmit data
+    CS(as3935_channel);
     for(uint8_t x = 0; x < len; ++x){
         WAITX(!(SPI1->SR & SPI_SR_TXE));
         SPI1->DR = buf[x];
@@ -53,6 +55,7 @@ uint8_t SPI_transmit(uint8_t *buf, uint8_t len){
         WAITX(!(SPI1->SR & SPI_SR_RXNE));
         buf[x] = SPI1->DR;
     }
+    CS_OFF();
     return len;
 }
 
diff --git a/F1:F103/AS3935-lightning/spi.h b/F1:F103/AS3935-lightning/spi.h
index 6e4a2f7..a95f1aa 100644
--- a/F1:F103/AS3935-lightning/spi.h
+++ b/F1:F103/AS3935-lightning/spi.h
@@ -27,6 +27,8 @@ typedef enum{
 } spiStatus;
 
 extern spiStatus SPI_status;
+// SPI channel number for `CS` macro
+extern uint8_t as3935_channel;
 
 void spi_setup();
 uint8_t SPI_transmit(uint8_t *buf, uint8_t len);
diff --git a/F1:F103/AS3935-lightning/usb_descr.c b/F1:F103/AS3935-lightning/usb_descr.c
index f6cc65c..cfa715c 100644
--- a/F1:F103/AS3935-lightning/usb_descr.c
+++ b/F1:F103/AS3935-lightning/usb_descr.c
@@ -15,6 +15,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <string.h> // memcpy
+
+#include "flash.h" // MAX_IINTERFACE_SZ, the_conf
 #include "usb_descr.h"
 
 // low/high for uint16_t
@@ -143,14 +146,22 @@ _USB_LANG_ID_(LD, LANG_US);
 _USB_STRING_(SD, u"0.0.1");
 _USB_STRING_(MD, u"eddy@sao.ru");
 _USB_STRING_(PD, u"AS3935 lightning detector");
-_USB_STRING_(ID, u"lightning_det");
+
+// iInterface will change on initialisation by config
+#define _USB_IIDESCR_(str) {sizeof(str), 0x03, str}
+typedef struct{
+    uint8_t  bLength;
+    uint8_t  bDescriptorType;
+    uint16_t bString[MAX_IINTERFACE_SZ];
+}iidescr_t;
+static iidescr_t iid = _USB_IIDESCR_(u"lightning_det");
 
 static const void* const StringDescriptor[iDESCR_AMOUNT] = {
     [iLANGUAGE_DESCR] = &LD,
     [iMANUFACTURER_DESCR] = &MD,
     [iPRODUCT_DESCR] = &PD,
     [iSERIAL_DESCR] = &SD,
-    [iINTERFACE_DESCR1] = &ID
+    [iINTERFACE_DESCR1] = &iid
 };
 
 static void wr0(const uint8_t *buf, uint16_t size, uint16_t askedsize){
@@ -208,3 +219,11 @@ void get_descriptor(config_pack_t *pack){
             break;
     }
 }
+
+void setup_interfaces(){
+    if(the_conf.iIlength){
+        iid.bLength = the_conf.iIlength + 2; // +2 - for bLength and bDescriptorType
+        memcpy(iid.bString, the_conf.iInterface, the_conf.iIlength);
+    }
+    iid.bDescriptorType = 0x03;
+}
diff --git a/F1:F103/AS3935-lightning/usb_descr.h b/F1:F103/AS3935-lightning/usb_descr.h
index 0874763..55f7ad5 100644
--- a/F1:F103/AS3935-lightning/usb_descr.h
+++ b/F1:F103/AS3935-lightning/usb_descr.h
@@ -56,13 +56,8 @@ enum{
     iPRODUCT_DESCR,
     iSERIAL_DESCR,
     iINTERFACE_DESCR1,
-   /* iINTERFACE_DESCR2,
-    iINTERFACE_DESCR3,
-    iINTERFACE_DESCR4,
-    iINTERFACE_DESCR5,
-    iINTERFACE_DESCR6,
-    iINTERFACE_DESCR7,*/
     iDESCR_AMOUNT
 };
 
 void get_descriptor(config_pack_t *pack);
+void setup_interfaces();
diff --git a/F1:F103/AS3935-lightning/usb_lib.c b/F1:F103/AS3935-lightning/usb_lib.c
index 3e7189e..41ea6da 100644
--- a/F1:F103/AS3935-lightning/usb_lib.c
+++ b/F1:F103/AS3935-lightning/usb_lib.c
@@ -424,6 +424,7 @@ void USB_setup(){
     USB->BCDR |= USB_BCDR_DPPU; // turn ON DP pullup
     NVIC_EnableIRQ(USB_UCPD1_2_IRQn);
 #endif
+    setup_interfaces();
 }
 
 
diff --git a/F1:F103/AS3935-lightning/version.inc b/F1:F103/AS3935-lightning/version.inc
index 34c03ee..e839456 100644
--- a/F1:F103/AS3935-lightning/version.inc
+++ b/F1:F103/AS3935-lightning/version.inc
@@ -1,2 +1,2 @@
-#define BUILD_NUMBER "25"
-#define BUILD_DATE "2026-04-11"
+#define BUILD_NUMBER "43"
+#define BUILD_DATE "2026-04-14"