int i2c_init_master(i2c_t dev, i2c_speed_t speed)
{
int ccr;
if ((unsigned int)dev >= I2C_NUMOF) {
return -1;
}
/* read speed configuration */
switch (speed) {
case I2C_SPEED_NORMAL:
ccr = I2C_APBCLK / 200000;
break;
case I2C_SPEED_FAST:
ccr = I2C_APBCLK / 800000;
break;
default:
return -2;
}
I2C_TypeDef *i2c = i2c_config[dev].dev;
/* enable I2C clock */
i2c_poweron(dev);
/* set IRQn priority */
NVIC_SetPriority(i2c_config[dev].er_irqn, I2C_IRQ_PRIO);
/* enable IRQn */
NVIC_EnableIRQ(i2c_config[dev].er_irqn);
/* configure pins */
gpio_init(i2c_config[dev].scl, GPIO_DIR_OUT, GPIO_PULLUP);
gpio_init_af(i2c_config[dev].scl, i2c_config[dev].af);
gpio_init(i2c_config[dev].sda, GPIO_DIR_OUT, GPIO_PULLUP);
gpio_init_af(i2c_config[dev].sda, i2c_config[dev].af);
/* configure device */
_i2c_init(i2c, ccr);
return 0;
}
int i2c_init_master(i2c_t dev, i2c_speed_t speed)
{
/* TWI Bit Rate Register - division factor for the bit rate generator */
unsigned long twibrr;
/* TWI Prescaler Bits - default 0 */
uint8_t twipb = 0;
/* check if the line is valid */
if (dev >= I2C_NUMOF) {
return -1;
}
/* calculate speed configuration */
switch (speed) {
case I2C_SPEED_LOW:
if ((CLOCK_CORECLOCK > 20000000UL)
|| (CLOCK_CORECLOCK < 1000000UL)) {
return -2;
}
twibrr = ((CLOCK_CORECLOCK / 10000UL) - 16) / (2 * 4); /* CLK Prescaler 4 */
twipb = 1;
break;
case I2C_SPEED_NORMAL:
if ((CLOCK_CORECLOCK > 50000000UL)
|| (CLOCK_CORECLOCK < 2000000UL)) {
return -2;
}
twibrr = ((CLOCK_CORECLOCK / 100000UL) - 16) / 2;
break;
case I2C_SPEED_FAST:
if (CLOCK_CORECLOCK < 7500000UL) {
return -2;
}
twibrr = ((CLOCK_CORECLOCK / 400000UL) - 16) / 2;
break;
case I2C_SPEED_FAST_PLUS:
if (CLOCK_CORECLOCK < 18000000UL) {
return -2;
}
twibrr = ((CLOCK_CORECLOCK / 1000000UL) - 16) / 2;
break;
case I2C_SPEED_HIGH:
if (CLOCK_CORECLOCK < 62000000UL) {
return -2;
}
twibrr = ((CLOCK_CORECLOCK / 3400000UL) - 16) / 2;
break;
default:
return -2;
}
/* set pull-up on SCL and SDA */
I2C_PORT_REG |= (I2C_PIN_MASK);
/* enable I2C clock */
i2c_poweron(dev);
/* disable device */
TWCR &= ~(1 << TWEN);
/* configure I2C clock */
TWBR = (uint8_t)twibrr; /* Set TWI Bit Rate Register */
TWSR &= ~(0x03); /* Reset TWI Prescaler Bits */
TWSR |= twipb; /* Set TWI Prescaler Bits */
/* enable device */
TWCR |= (1 << TWEN);
return 0;
}