void i2c_enable(i2c_t i2c, i2c_clock_mode_t mode)
{
uint32_t pclk, freq;
const _i2c_t *_i2c = i2c;
// Disable the I2C EV and ERR interrupt lines in the NVIC
nvic_disable_interrupt_line(_i2c->irq_line_ev);
nvic_disable_interrupt_line(_i2c->irq_line_er);
// Enable the clock for this peripheral
rcc_apb_enable(_i2c->apb_bus, _i2c->apb_bit);
// Reset the peripheral
*i2c_get_CR1(_i2c) = I2C_CR1__SWRST;
// Clear all registers
*i2c_get_CR2(_i2c) = 0;
*i2c_get_CCR(_i2c) = 0;
*i2c_get_TRISE(_i2c) = 0;
*i2c_get_SR1(_i2c) = 0;
*i2c_get_SR2(_i2c) = 0;
*i2c_get_OAR1(_i2c) = 0;
*i2c_get_OAR2(_i2c) = 0;
// Release SWRST
*i2c_get_CR1(_i2c) = 0;
/* Step 1: program the peripheral input clock in CR2 */
// Compute clock frequency
pclk = rcc_sysclk_get_clock_frequency(
_i2c->apb_bus == 1 ? RCC_SYSCLK_CLOCK_PCLK1
: RCC_SYSCLK_CLOCK_PCLK2);
freq = pclk / 1000000;
*i2c_get_CR2(_i2c) = freq & I2C_CR2__FREQ_MASK;
/* Step 2: configure the clock control registers */
if (mode == I2C_CLOCK_MODE_FAST)
{
// Set Fast Speed mode and bitrate: ~400kHz
uint32_t ccr = freq * 10;
ccr = ccr / 12 + (ccr % 12 ? 1 : 0);
*i2c_get_CCR(_i2c) = I2C_CCR__FS | ccr;
}
else
{
// Set Standard Speed mode and bitrate: 100kHz
*i2c_get_CCR(_i2c) = (freq * 5) & I2C_CCR__CCR_MASK;
}
/* Step 3: configure the rise time registers */
if (mode == I2C_CLOCK_MODE_FAST)
{
// Configure maximum rise time
*i2c_get_TRISE(_i2c) = (freq * 3 / 10 + 1) & I2C_TRISE__TRISE_MASK;
}
else
{
// Configure maximum rise time
*i2c_get_TRISE(_i2c) = (freq + 1) & I2C_TRISE__TRISE_MASK;
}
/* Step 4: program the CR1 register to enable the peripheral */
// Enable I2C
*i2c_get_CR1(_i2c) = I2C_CR1__PE;
// Enable EVT and ERR interrupt
// Note: do not enable BUF to avoid stm32f problem
*i2c_get_CR2(_i2c) |= I2C_CR2__ITEVTEN | I2C_CR2__ITERREN;
// Initialize I2C state
_i2c->data->state = I2C_IDLE;
_i2c->data->len_send = 0;
_i2c->data->len_recv = 0;
_i2c->data->cpt_send = 0;
_i2c->data->cpt_recv = 0;
_i2c->data->transfer_handler = NULL;
// Enable I2C EV and ERR interrupt line in the NVIC
nvic_enable_interrupt_line(_i2c->irq_line_ev);
nvic_enable_interrupt_line(_i2c->irq_line_er);
}
void i2c_enable(i2c_t i2c, i2c_clock_mode_t mode)
{
uint32_t pclk, freq;
_i2c_t *_i2c = i2c;
// Disable the I2C EV and ERR interrupt lines in the NVIC
nvic_disable_interrupt_line(_i2c->irq_line_ev);
nvic_disable_interrupt_line(_i2c->irq_line_er);
// Enable the clock for this peripheral
rcc_apb_enable(_i2c->apb_bus, _i2c->apb_bit);
// Reset the peripheral
*i2c_get_CR1(_i2c) = I2C_CR1__SWRST;
// Clear all registers
*i2c_get_CR1(_i2c) = 0;
*i2c_get_CR2(_i2c) = 0;
*i2c_get_CCR(_i2c) = 0;
*i2c_get_TRISE(_i2c) = 0;
*i2c_get_SR1(_i2c) = 0;
*i2c_get_SR2(_i2c) = 0;
/* Step 1: program the peripheral input clock in CR2 */
// Compute clock frequency
pclk = rcc_sysclk_get_clock_frequency(
_i2c->apb_bus == 1 ? RCC_SYSCLK_CLOCK_PCLK1
: RCC_SYSCLK_CLOCK_PCLK2);
freq = pclk / 1000000;
*i2c_get_CR2(_i2c) = freq & I2C_CR2__FREQ_MASK;
/* Step 2: configure the clock control registers */
if (mode == I2C_CLOCK_MODE_FAST)
{
// Set Fast Speed mode and bitrate: 400kHz with duty t_low/t_high = 16/9
*i2c_get_CCR(_i2c) = I2C_CCR__FS | I2C_CCR__DUTY | (freq / 10 * 25);
}
else
{
// Set Standard Speed mode and bitrate: 100kHz
*i2c_get_CCR(_i2c) = (freq * 5) & I2C_CCR__CCR_MASK;
}
/* Step 3: configure the rise time registers */
if (mode == I2C_CLOCK_MODE_FAST)
{
// Configure maximum rise time
*i2c_get_TRISE(_i2c) = (freq * 3 / 10 + 1) & I2C_TRISE__TRISE_MASK;
}
else
{
// Configure maximum rise time
*i2c_get_TRISE(_i2c) = (freq + 1) & I2C_TRISE__TRISE_MASK;
}
/* Step 4: program the CR1 register to enable the peripheral */
// Set I2C mode, enable ACK and enable I2C
*i2c_get_CR1(_i2c) = I2C_CR1__ACK | I2C_CR1__PE;
// Enable EV and BUF interrupt
*i2c_get_CR2(_i2c) |= I2C_CR2__ITEVTEN | I2C_CR2__ITBUFEN
| I2C_CR2__ITERREN;
// Initialize I2C state
state = I2C_IDLE;
// Enable I2C EV and ERR interrupt line in the NVIC
nvic_enable_interrupt_line(_i2c->irq_line_ev);
nvic_enable_interrupt_line(_i2c->irq_line_er);
}
