i2c_general.c
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/* 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/>.
*
*/
/* standard libraries */
#include <stdint.h> // standard integer types
//#include <stdio.h> // standard I/O facilities
#include <stdlib.h> // general utilities
/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/stm32/i2c.h> // I2C library
#include <libopencm3/stm32/timer.h> // timer utilities
/* own libraries */
#include "global.h" // global utilities
#include "i2c_general.h" // I2C header and definitions
#define I2C_GENERAL_I2C 2
#define I2C_GENERAL_TIMER 3
#define I2C_GENERAL_TIMEOUT 4
void i2c_general_setup_master(bool fast)
{
// configure I2C peripheral
rcc_periph_clock_enable(RCC_I2C_SCL_PORT(I2C_GENERAL_I2C)); // enable clock for I2C I/O peripheral
gpio_set(I2C_SCL_PORT(I2C_GENERAL_I2C), I2C_SCL_PIN(I2C_GENERAL_I2C)); // already put signal high to avoid small pulse
gpio_set_mode(I2C_SCL_PORT(I2C_GENERAL_I2C), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, I2C_SCL_PIN(I2C_GENERAL_I2C)); // setup I2C I/O pins
rcc_periph_clock_enable(RCC_I2C_SCL_PORT(I2C_GENERAL_I2C)); // enable clock for I2C I/O peripheral
gpio_set(I2C_SDA_PORT(I2C_GENERAL_I2C), I2C_SDA_PIN(I2C_GENERAL_I2C)); // already put signal high to avoid small pulse
gpio_set_mode(I2C_SDA_PORT(I2C_GENERAL_I2C), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, I2C_SDA_PIN(I2C_GENERAL_I2C)); // setup I2C I/O pins
rcc_periph_clock_enable(RCC_AFIO); // enable clock for alternate function
rcc_periph_clock_enable(RCC_I2C(I2C_GENERAL_I2C)); // enable clock for I2C peripheral
i2c_reset(I2C(I2C_GENERAL_I2C)); // reset configuration
i2c_peripheral_disable(I2C(I2C_GENERAL_I2C)); // I2C needs to be disable to be configured
i2c_set_clock_frequency(I2C(I2C_GENERAL_I2C), rcc_apb1_frequency/1000000); // configure the peripheral clock to the APB1 freq (where it is connected to)
if (fast) {
i2c_set_fast_mode(I2C(I2C_GENERAL_I2C));
i2c_set_ccr(I2C(I2C_GENERAL_I2C), rcc_apb1_frequency/(400000*2)); // set Thigh/Tlow to generate frequency of 400 kHz
i2c_set_trise(I2C(I2C_GENERAL_I2C), (300/(1000/(rcc_apb1_frequency/1000000)))+1); // max rise time for 300 kHz is 300 ns
} else {
i2c_set_standard_mode(I2C(I2C_GENERAL_I2C)); // the DS1307 has a maximum I2C SCL freq if 100 kHz (corresponding to the standard mode)
i2c_set_ccr(I2C(I2C_GENERAL_I2C), rcc_apb1_frequency/(100000*2)); // set Thigh/Tlow to generate frequency of 100 kHz
i2c_set_trise(I2C(I2C_GENERAL_I2C), (1000/(1000/(rcc_apb1_frequency/1000000)))+1); // max rise time for 100 kHz is 1000 ns (~1 MHz)
}
i2c_peripheral_enable(I2C(I2C_GENERAL_I2C)); // enable I2C after configuration completed
// configure time for timeouts
rcc_periph_clock_enable(RCC_TIM(I2C_GENERAL_TIMER)); // enable clock for timer block
timer_reset(TIM(I2C_GENERAL_TIMER)); // reset timer state
timer_set_mode(TIM(I2C_GENERAL_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock, edge alignment (simple count), and count up
timer_one_shot_mode(TIM(I2C_GENERAL_TIMER)); // stop counter after update event (we only need to one timeout and reset before next operation)
if (fast) {
timer_set_prescaler(TIM(I2C_GENERAL_TIMER), rcc_ahb_frequency/400000-1); // set the prescaler so one tick is also one I2C bit (used I2C frequency)
} else {
timer_set_prescaler(TIM(I2C_GENERAL_TIMER), rcc_ahb_frequency/100000-1); // set the prescaler so one tick is also one I2C bit (used I2C frequency)
}
timer_set_period(TIM(I2C_GENERAL_TIMER), I2C_GENERAL_TIMEOUT*9); // use factor to wait for all 9 bits to be transmitted
timer_update_on_overflow(TIM(I2C_GENERAL_TIMER)); // only use counter overflow as UEV source (use overflow as timeout)
// wait one transaction for the signal to be stable (some slave have issues when an I2C transaction immediately follows)
timer_set_counter(TIM(I2C_GENERAL_TIMER),0); // restart timer
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
timer_enable_counter(TIM(I2C_GENERAL_TIMER)); // enable timer for timeouts
while ( !timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF));
timer_disable_counter(TIM(I2C_GENERAL_TIMER)); // disable timer for timeouts
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
}
bool i2c_general_check(void)
{
return (0!=gpio_get(I2C_SCL_PORT(I2C_GENERAL_I2C), I2C_SCL_PIN(I2C_GENERAL_I2C)) && 0!=gpio_get(I2C_SDA_PORT(I2C_GENERAL_I2C), I2C_SDA_PIN(I2C_GENERAL_I2C)));
}
bool i2c_general_start(void)
{
// send (re-)start condition
i2c_send_start(I2C(I2C_GENERAL_I2C)); // send start condition to start transaction
timer_set_counter(TIM(I2C_GENERAL_TIMER), 0); // restart timer
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
timer_enable_counter(TIM(I2C_GENERAL_TIMER)); // enable timer for timeouts
while (!(I2C_SR1(I2C(I2C_GENERAL_I2C)) & I2C_SR1_SB) && !timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)); // wait until start condition is transmitted
timer_disable_counter(TIM(I2C_GENERAL_TIMER)); // disable timer for timeouts
if (timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)) { // timeout occurred
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
return false;
}
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_MSL)) { // verify if in master mode
return false;
}
return true;
}
bool i2c_general_select_slave(uint8_t slave, bool write)
{
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_BUSY)) { // I2C device is not busy (start condition has not been sent)
if (!i2c_general_start()) { // send start condition
return false; // could not send start condition
}
}
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_MSL)) { // I2C device is already not master mode
return false;
}
// select slave
i2c_send_7bit_address(I2C(I2C_GENERAL_I2C), slave, write ? I2C_WRITE : I2C_READ); // select slave, with read/write flag
timer_set_counter(TIM(I2C_GENERAL_TIMER), 0); // restart timer
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
timer_enable_counter(TIM(I2C_GENERAL_TIMER)); // enable timer for timeouts
while (!(I2C_SR1(I2C(I2C_GENERAL_I2C)) & I2C_SR1_ADDR) && !timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)); // wait until address is transmitted
timer_disable_counter(TIM(I2C_GENERAL_TIMER)); // disable timer for timeouts
if (timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)) { // timeout occurred (no ACK received)
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
return false;
}
if (write) {
if (!((I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_TRA))) { // verify we are in transmit mode (and read SR2 to clear ADDR)
return false;
}
} else {
if ((I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_TRA)) { // verify we are in read mode (and read SR2 to clear ADDR)
return false;
}
}
return true;
}
bool i2c_general_read(uint8_t* data, size_t data_size)
{
// sanity check
if (data==NULL || data_size==0) { // no data to read
return true;
}
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_BUSY)) { // I2C device is not busy (start condition has not been sent)
return false; // address has probably also not been sent
}
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_MSL)) { // I2C device not master mode
return false;
}
// read data
for (size_t i=0; i<data_size; i++) { // read bytes
if (i==data_size-1) { // prepare to sent NACK for last byte
i2c_disable_ack(I2C(I2C_GENERAL_I2C)); // NACK received to stop slave transmission
i2c_send_stop(I2C(I2C_GENERAL_I2C)); // send STOP after receiving byte
} else {
i2c_enable_ack(I2C(I2C_GENERAL_I2C)); // ACK received byte to continue slave transmission
}
timer_set_counter(TIM(I2C_GENERAL_TIMER), 0); // restart timer
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
timer_enable_counter(TIM(I2C_GENERAL_TIMER)); // enable timer for timeouts
while (!(I2C_SR1(I2C(I2C_GENERAL_I2C)) & I2C_SR1_RxNE) && !timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)); // wait until byte has been received
timer_disable_counter(TIM(I2C_GENERAL_TIMER)); // disable timer for timeouts
if (timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)) { // timeout occurred
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
return false;
}
data[i] = i2c_get_data(I2C(I2C_GENERAL_I2C)); // read received byte
}
return true;
}
bool i2c_general_write(const uint8_t* data, size_t data_size)
{
// sanity check
if (data==NULL || data_size==0) { // no data to write
return true;
}
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_BUSY)) { // I2C device is not busy (start condition has not been sent)
return false; // address has probably also not been sent
}
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_MSL)) { // I2C device is not master mode
return false;
}
// write data
for (size_t i=0; i<data_size; i++) { // write bytes
i2c_send_data(I2C(I2C_GENERAL_I2C), data[i]); // send byte to be written in memory
timer_set_counter(TIM(I2C_GENERAL_TIMER),0); // restart timer
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
timer_enable_counter(TIM(I2C_GENERAL_TIMER)); // enable timer for timeouts
while (!(I2C_SR1(I2C(I2C_GENERAL_I2C)) & I2C_SR1_TxE) && !timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)); // wait until byte has been transmitted
timer_disable_counter(TIM(I2C_GENERAL_TIMER)); // disable timer for timeouts
if (timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)) { // timeout occurred (no ACK received)
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
return false;
}
}
return true;
}
void i2c_general_stop(void)
{
// sanity check
if (!(I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_BUSY)) { // release is not busy
return; // bus has probably already been released
}
// send stop condition
i2c_send_stop(I2C(I2C_GENERAL_I2C)); // send stop to release bus
timer_set_counter(TIM(I2C_GENERAL_TIMER), 0); // restart timer
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
timer_enable_counter(TIM(I2C_GENERAL_TIMER)); // enable timer for timeouts
while ((I2C_SR2(I2C(I2C_GENERAL_I2C)) & I2C_SR2_MSL) && !timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)); // wait until bus released (non master mode)
timer_disable_counter(TIM(I2C_GENERAL_TIMER)); // disable timer for timeouts
if (timer_get_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF)) { // timeout occurred
timer_clear_flag(TIM(I2C_GENERAL_TIMER), TIM_SR_UIF); // clear flag
}
}
I2C_SCL_PORT
#define I2C_SCL_PORT(x)
get I2C port for SCL pin based on I2C identifier
Definition: global.h:272
I2C
#define I2C(x)
get I2C based on I2C identifier
Definition: global.h:260
i2c_general_select_slave
bool i2c_general_select_slave(uint8_t slave, bool write)
select slave device
Definition: i2c_general.c:122
I2C_SDA_PIN
#define I2C_SDA_PIN(x)
get I2C port for SDA pin based on I2C identifier
Definition: global.h:278
global.h
global definitions and methods (API)
I2C_SDA_PORT
#define I2C_SDA_PORT(x)
get I2C port for SDA pin based on I2C identifier
Definition: global.h:274
RCC_TIM
#define RCC_TIM(x)
get RCC for timer based on TIM identifier
Definition: global.h:109
i2c_general_read
bool i2c_general_read(uint8_t *data, size_t data_size)
read data
Definition: i2c_general.c:157
i2c_general_check
bool i2c_general_check(void)
check if SDA and SCL signals are high
Definition: i2c_general.c:97
I2C_GENERAL_TIMEOUT
#define I2C_GENERAL_TIMEOUT
timeout factor (compared to expected time)
Definition: i2c_general.c:47
I2C_GENERAL_I2C
#define I2C_GENERAL_I2C
I2C peripheral.
Definition: i2c_general.c:40
i2c_general.h
library to communicate using I2C as master or slave (API)
i2c_general_stop
void i2c_general_stop(void)
sent stop condition
Definition: i2c_general.c:223
I2C_SCL_PIN
#define I2C_SCL_PIN(x)
get I2C pin for SCL pin based on I2C identifier
Definition: global.h:276
i2c_general_start
bool i2c_general_start(void)
send start condition
Definition: i2c_general.c:102
RCC_I2C_SCL_PORT
#define RCC_I2C_SCL_PORT(x)
get RCC for GPIO port for SCL based on I2C identifier
Definition: global.h:264
i2c_general_write
bool i2c_general_write(const uint8_t *data, size_t data_size)
write data
Definition: i2c_general.c:193
TIM
#define TIM(x)
get TIM based on TIM identifier
Definition: global.h:107
I2C_GENERAL_TIMER
#define I2C_GENERAL_TIMER
timer peripheral
Definition: i2c_general.c:46
RCC_I2C
#define RCC_I2C(x)
get RCC for I2C based on I2C identifier
Definition: global.h:262