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stm32samples/F3:F303/I2C_scan/i2c.c
Edward Emelianov 934f4fbddd start working with DMA
2025-09-18 23:54:01 +03:00

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/*
* This file is part of the i2cscan 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 <stm32f3.h>
#include <string.h>
#include "i2c.h"
#include "strfunc.h" // hexdump
#include "usb_dev.h"
i2c_speed_t i2c_curspeed = I2C_SPEED_AMOUNT;
extern volatile uint32_t Tms;
static uint32_t cntr;
volatile uint8_t i2c_scanmode = 0; // == 1 when I2C is in scan mode
static volatile uint8_t i2c_got_DMA = 0; // got DMA data
static uint8_t i2caddr = I2C_ADDREND; // current address in scan mode
static volatile int I2Cbusy = 0, goterr = 0; // busy==1 when DMA active, goterr==1 if 't was error @ last sent
static uint8_t I2Cbuf[I2C_BUFSIZE];
static uint16_t i2cbuflen = 0; // buffer for DMA tx/rx and its len
static volatile uint16_t dma_remain = 0; // remain bytes of DMA read/write
static uint8_t bigendian = 0; // ==1 for big-endian 16-bit data
static uint8_t dma16bit = 0; // 16-bit reading - possible need conversion from bigendian
// macros for I2C rx/tx
#define DMARXCCR (DMA_CCR_MINC | DMA_CCR_TCIE | DMA_CCR_TEIE)
#define DMATXCCR (DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE | DMA_CCR_TEIE)
// macro for I2CCR1
#define I2CCR1 (I2C_CR1_PE | I2C_CR1_RXDMAEN | I2C_CR1_TXDMAEN)
// return 1 if I2Cbusy is set & timeout reached
static inline int isI2Cbusy(){
cntr = Tms;
do{
if(Tms - cntr > I2C_TIMEOUT){ U("Timeout, DMA transfer in progress?"); return 1;}
}while(I2Cbusy);
return 0;
}
// GPIO Resources: I2C1_SCL - PB6 (AF4), I2C1_SDA - PB7 (AF4)
void i2c_setup(i2c_speed_t speed){
uint8_t PRESC, SCLDEL = 0x04, SDADEL = 0x03, SCLH, SCLL; // I2C1->TIMINGR fields
switch(speed){
case I2C_SPEED_10K:
PRESC = 0x0F;
SCLH = 0xDA;
SCLL = 0xE0;
break;
case I2C_SPEED_100K:
PRESC = 0x0F;
SCLH = 0x13;
SCLL = 0x16;
break;
case I2C_SPEED_400K:
PRESC = 0x07;
SCLH = 0x08;
SCLL = 0x09;
break;
case I2C_SPEED_1M:
SDADEL = 1;
SCLDEL = 2;
PRESC = 0x3;
SCLH = 0x4;
SCLL = 0x6;
break;
case I2C_SPEED_2M:
SDADEL = 0;
SCLDEL = 1;
PRESC = 0x0;
SCLH = 0x1;
SCLL = 0x2;
break;
default:
USND("Wrong I2C speed!");
return; // wrong speed
}
RCC->AHBENR |= RCC_AHBENR_GPIOBEN;
I2C1->CR1 = 0; // disable I2C for setup
I2C1->ICR = 0x3f38; // clear all errors
GPIOB->AFR[0] = (GPIOB->AFR[0] & ~(GPIO_AFRL_AFRL6 | GPIO_AFRL_AFRL7)) |
AFRf(4, 6) | AFRf(4, 7);
GPIOB->MODER = (GPIOB->MODER & ~(GPIO_MODER_MODER6 | GPIO_MODER_MODER7)) |
GPIO_MODER_MODER6_AF | GPIO_MODER_MODER7_AF;
GPIOB->PUPDR = (GPIOB->PUPDR & !(GPIO_PUPDR_PUPDR6 | GPIO_PUPDR_PUPDR7)) |
GPIO_PUPDR6_PU | GPIO_PUPDR7_PU; // pullup (what if there's no external pullup?)
GPIOB->OTYPER |= GPIO_OTYPER_OT_6 | GPIO_OTYPER_OT_7; // both open-drain outputs
// I2C (default timing from sys clock - 72MHz)
RCC->APB1ENR |= RCC_APB1ENR_I2C1EN; // clocking
if(speed < I2C_SPEED_400K){ // slow cpeed - common mode
SYSCFG->CFGR1 &= ~(SYSCFG_CFGR1_I2C1_FMP | SYSCFG_CFGR1_I2C_PB6_FMP | SYSCFG_CFGR1_I2C_PB7_FMP);
}else{ // activate "fast mode plus"
SYSCFG->CFGR1 |= SYSCFG_CFGR1_I2C1_FMP | SYSCFG_CFGR1_I2C_PB6_FMP | SYSCFG_CFGR1_I2C_PB7_FMP;
}
I2C1->TIMINGR = (PRESC<<I2C_TIMINGR_PRESC_Pos) | (SCLDEL<<I2C_TIMINGR_SCLDEL_Pos) |
(SDADEL<<I2C_TIMINGR_SDADEL_Pos) | (SCLH<<I2C_TIMINGR_SCLH_Pos) | (SCLL<< I2C_TIMINGR_SCLL_Pos);
I2C1->CR1 = I2CCR1;
RCC->AHBENR |= RCC_AHBENR_DMA1EN;
NVIC_EnableIRQ(DMA1_Channel6_IRQn);
NVIC_EnableIRQ(DMA1_Channel7_IRQn);
I2Cbusy = 0;
i2c_curspeed = speed;
}
// setup DMA for rx (tx==0) or tx (tx==1)
// DMA channels: 7 - I2C1_Rx, 6 - I2C1_Tx
static void i2cDMAsetup(int tx, uint16_t len){
i2cbuflen = len;
if(len > 255) len = 255;
if(tx){
DMA1_Channel6->CCR = DMATXCCR;
DMA1_Channel6->CPAR = (uint32_t) &I2C1->TXDR;
DMA1_Channel6->CMAR = (uint32_t) I2Cbuf;
DMA1_Channel6->CNDTR = len;
}else{
DMA1_Channel7->CCR = DMARXCCR;
DMA1_Channel7->CPAR = (uint32_t) &I2C1->RXDR;
DMA1_Channel7->CMAR = (uint32_t) I2Cbuf;
DMA1_Channel7->CNDTR = len;
}
}
// wait until bit set or clear; return 1 if OK, 0 in case of timeout
static uint8_t waitISRbit(uint32_t bit, uint8_t isset){
uint32_t waitwhile = (isset) ? 0 : bit; // wait until !=
const char *errmsg = NULL;
cntr = Tms;
if(bit != I2C_ISR_RXNE){ U("ISR wait "); U(uhex2str(bit)); USND(isset ? "set" : "reset"); }
while((I2C1->ISR & bit) == waitwhile){
IWDG->KR = IWDG_REFRESH;
if(I2C1->ISR & I2C_ISR_NACKF){
errmsg = "NAK";
goto goterr;
}
if(Tms - cntr > I2C_TIMEOUT){
errmsg = "timeout";
goto goterr;
}
}
return 1;
goterr:
U("wait ISR bit: "); USND(errmsg);
U("I2c->ISR = "); USND(uhex2str(I2C1->ISR));
I2C1->ICR = 0xff;
return 0;
}
// start writing
static uint8_t i2c_startw(uint8_t addr, uint16_t nbytes, uint8_t stop){
if(!waitISRbit(I2C_ISR_BUSY, 0)) return 0;
I2C1->CR2 = nbytes << 16 | addr;
if(stop){
I2C1->CR2 |= I2C_CR2_AUTOEND; // autoend
}else{
//I2C1->CR2 &= ~I2C_CR2_AUTOEND;
//I2C1->CR2 |= I2C_CR2_RELOAD;
}
// now start transfer
I2C1->CR2 |= I2C_CR2_START;
return 1;
}
/**
* write command byte to I2C
* @param addr - device address
* @param data - bytes to write
* @param nbytes - amount of bytes to write
* @param stop - to set STOP
* @return 0 if error
*/
static uint8_t write_i2cs(uint8_t addr, uint8_t *data, uint16_t nbytes, uint8_t stop){
if(!i2c_startw(addr, nbytes, stop)) return 0;
for(int i = 0; i < nbytes; ++i){
cntr = Tms;
while(!(I2C1->ISR & I2C_ISR_TXIS)){ // ready to transmit
IWDG->KR = IWDG_REFRESH;
if(I2C1->ISR & I2C_ISR_NACKF){
I2C1->ICR |= I2C_ICR_NACKCF;
USND("write_i2cs: NAK");
return 0;
}
if(Tms - cntr > I2C_TIMEOUT){
USND("write_i2cs: Timeout");
return 0;
}
}
I2C1->TXDR = data[i]; // send data
U("write_i2cs: "); USND(uhex2str(data[i]));
}
cntr = Tms;
if(stop){
if(!waitISRbit(I2C_ISR_BUSY, 0)) return 0;
}else{ // repeated start
if(!waitISRbit(I2C_ISR_TC, 1)) return 0;
}
return 1;
}
uint8_t write_i2c(uint8_t addr, uint8_t *data, uint16_t nbytes){
if(isI2Cbusy()) return 0;
return write_i2cs(addr, data, nbytes, 1);
}
/*
uint8_t write_i2c16(uint8_t addr, uint8_t *data, uint8_t nbytes){
if(isI2Cbusy()) return 0;
return write_i2cs(addr, data, nbytes, 1);
}*/
uint8_t write_i2c_dma(uint8_t addr, uint8_t *data, uint16_t nbytes){
if(!data || nbytes < 1 || nbytes > I2C_BUFSIZE) return 0;
if(isI2Cbusy()) return 0;
memcpy(I2Cbuf, data, nbytes);
i2cDMAsetup(1, nbytes);
goterr = 0;
if(!i2c_startw(addr, nbytes, 1)) return 0;
I2Cbusy = 1;
DMA1_Channel6->CCR = DMATXCCR | DMA_CCR_EN; // start transfer
return 1;
}
uint8_t write_i2c_dma16(uint8_t addr, uint16_t *data, uint16_t nwords){
if(!data || nwords < 1 || nwords > I2C_BUFSIZE/2) return 0;
if(isI2Cbusy()) return 0;
uint16_t nbytes = nwords << 1;
if(bigendian){
for(uint16_t i = 0; i < nwords; ++i)
I2Cbuf[i] = __REV16(data[i]);
}else memcpy(I2Cbuf, (uint8_t*)data, nbytes);
i2cDMAsetup(1, nbytes);
goterr = 0;
if(!i2c_startw(addr, nbytes, 1)) return 0;
I2Cbusy = 1;
DMA1_Channel6->CCR = DMATXCCR | DMA_CCR_EN; // start transfer
return 1;
}
// start reading of `nbytes` from `addr`; if `start`==`, set START
static uint8_t i2c_startr(uint8_t addr, uint16_t nbytes, uint8_t start){
uint32_t cr2 = addr | I2C_CR2_RD_WRN;
if(nbytes > 255){
nbytes = 255; cr2 |= I2C_CR2_RELOAD;
}else cr2 |= I2C_CR2_AUTOEND;
cr2 |= (nbytes << 16);
I2C1->CR2 = (start) ? cr2 | I2C_CR2_START : cr2;
return 1;
}
/**
* read nbytes of data from I2C line
* all functions with `addr` should have addr = address << 1
* `data` should be an array with at least `nbytes` length
* @return 1 if all OK, 0 if NACK or no device found
*/
static uint8_t *read_i2cb(uint8_t addr, uint16_t nbytes, uint8_t busychk){
if(busychk && !waitISRbit(I2C_ISR_BUSY, 0)) return NULL;
uint8_t start = 1;
uint8_t *bptr = I2Cbuf;
while(nbytes){
U("Read "); U(u2str(nbytes)); USND(" bytes");
if(!i2c_startr(addr, nbytes, start)) return NULL;
if(nbytes < 256){
for(int i = 0; i < nbytes; ++i){
if(!waitISRbit(I2C_ISR_RXNE, 1)) goto tmout;
*bptr++ = I2C1->RXDR;
}
while(waitISRbit(I2C_ISR_RXNE, 1)){
U("OOOps! We have another byte: "); USND(uhex2str(I2C1->RXDR));
}
break;
}else while(!(I2C1->ISR & I2C_ISR_TCR)){ // until first part read
if(!waitISRbit(I2C_ISR_RXNE, 1)) goto tmout;
*bptr++ = I2C1->RXDR;
}
USND("next");
nbytes -= 255;
start = 0;
}
return I2Cbuf;
tmout:
USND("read I2C: Timeout");
return NULL;
}
uint8_t *read_i2c(uint8_t addr, uint16_t nbytes){
if(isI2Cbusy()) return 0;
return read_i2cb(addr, nbytes, 1);
}
static uint8_t dmard(uint8_t addr, uint16_t nbytes, uint8_t stop){
if(nbytes < 1 || nbytes > I2C_BUFSIZE) return 0;
if(isI2Cbusy()) return 0;
i2cDMAsetup(0, nbytes);
goterr = 0;
i2c_got_DMA = 0;
if(!i2c_startr(addr, nbytes, stop)) return 0;
dma_remain = nbytes > 255 ? nbytes - 255 : 0; // remainder after first read finish
(void) I2C1->RXDR; // avoid wrong first byte
DMA1_Channel7->CCR = DMARXCCR | DMA_CCR_EN; // init DMA before START sequence
I2Cbusy = 1;
return 1;
}
uint8_t read_i2c_dma(uint8_t addr, uint16_t nbytes){
uint8_t got = dmard(addr, nbytes, 1);
if(got) dma16bit = 0;
return got;
}
uint8_t read_i2c_dma16(uint8_t addr, uint16_t nwords){
if(nwords > I2C_BUFSIZE/2) return 0; // what if `nwords` is very large? we should check it
uint8_t got = dmard(addr, nwords<<1, 1);
if(got) dma16bit = 1;
return got;
}
static void swapbytes(uint16_t *data, uint16_t datalen){
if(!datalen) return;
for(int i = 0; i < datalen; ++i)
data[i] = __REV16(data[i]);
}
// read register reg
uint8_t *read_i2c_reg(uint8_t addr, uint8_t reg, uint16_t nbytes, uint8_t isdma){
if(isI2Cbusy()) return NULL;
if(!write_i2cs(addr, &reg, 1, 0)) return NULL;
if(isdma){
if(dmard(addr, nbytes, 0)){ dma16bit = 0; return I2Cbuf;} // for DMA we just return something non-null to check OK
return NULL;
}
return read_i2cb(addr, nbytes, 0);
}
// read 16bit register reg
uint16_t *read_i2c_reg16(uint8_t addr, uint16_t reg16, uint16_t nwords, uint8_t isdma){
if(isI2Cbusy() || nwords < 1 || nwords > I2C_BUFSIZE/2) return 0;
if(bigendian) reg16 = __REV16(reg16);
if(!write_i2cs(addr, (uint8_t*)&reg16, 2, 0)) return NULL;
if(isdma){
if(dmard(addr, nwords<<1, 0)){ dma16bit = 1; return (uint16_t*)I2Cbuf; }
return NULL;
}
if(!read_i2cb(addr, nwords*2, 0)) return NULL;
uint16_t *buf = (uint16_t*)I2Cbuf;
if(bigendian) swapbytes(buf, nwords);
return buf;
}
void i2c_init_scan_mode(){
i2caddr = 1; // start from 1 as 0 is a broadcast address
i2c_scanmode = 1;
}
// return 1 if next addr is active & return in as `addr`
// if addresses are over, return 1 and set addr to I2C_NOADDR
// if scan mode inactive, return 0 and set addr to I2C_NOADDR
int i2c_scan_next_addr(uint8_t *addr){
if(isI2Cbusy()) return 0;
*addr = i2caddr;
if(i2caddr == I2C_ADDREND){
*addr = I2C_ADDREND;
i2c_scanmode = 0;
return 0;
}
if(!read_i2c((i2caddr++)<<1, 1)) return 0;
return 1;
}
// dump I2Cbuf
void i2c_bufdudump(){
if(goterr){
USND("Last transfer ends with error!");
goterr = 0;
}
if(i2cbuflen < 1) return;
USND("I2C buffer:");
if(dma16bit) hexdump16(USB_sendstr, (uint16_t*)I2Cbuf, i2cbuflen);
hexdump(USB_sendstr, I2Cbuf, i2cbuflen);
}
// get DMA buffer with conversion to little-endian (if transfer was for 16-bit)
uint8_t *i2cdma_getbuf(uint16_t *len){
if(!i2c_got_DMA || i2cbuflen < 1) return NULL;
i2c_got_DMA = 0;
if(dma16bit){
i2cbuflen >>= 1; // for hexdump16 - now buffer have uint16_t!
uint16_t *b = (uint16_t*)I2Cbuf;
if(bigendian){
for(int i = 0; i < i2cbuflen; ++i) b[i] = __REV(b[i]);
}
}
if(len) *len = i2cbuflen;
return I2Cbuf;
}
int i2cdma_haderr(){
int r = goterr;
goterr = 0;
return r;
}
void endianness(uint8_t isbig){
bigendian = isbig;
}
// Rx (7) /Tx (6) interrupts
static void I2C_isr(int rx){
uint32_t isr = DMA1->ISR;
DMA_Channel_TypeDef *ch = (rx) ? DMA1_Channel7 : DMA1_Channel6;
ch->CCR &= ~DMA_CCR_EN; // clear enable for further settings
if(isr & (DMA_ISR_TEIF6 | DMA_ISR_TEIF7)){
goterr = 1; goto ret;
}
if(dma_remain){ // receive/send next portion
uint16_t len = (dma_remain > 255) ? 255 : dma_remain;
ch->CNDTR = len;
if(rx){
if(!i2c_startr(0, dma_remain, 0)){
goterr = 1; goto ret;
}
ch->CMAR += 255;
}
dma_remain -= len;
ch->CCR |= DMA_CCR_EN;
DMA1->IFCR = DMA_IFCR_CTCIF6 | DMA_IFCR_CTCIF7;
return;
}else if(rx) i2c_got_DMA = 1; // last transfer was Rx and all data read
ret:
ch->CCR = 0;
I2Cbusy = 0;
DMA1->IFCR = 0x0ff00000; // clear all flags for channel6/7
}
void dma1_channel6_isr(){
I2C_isr(0);
}
void dma1_channel7_isr(){
I2C_isr(1);
}
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