/**
* @brief Reads an 8-bit register from an I2C slave
*/
uint8_t i2c_read_register(register uint8_t slaveId, register uint8_t registerAddress){
/* loop while the bus is still busy */
i2c_wait_while_busy();
/* send I2C start signal and set write direction, also enables ACK */
i2c_send_start();
/* send the slave address and wait for the I2C bus operation to complete */
i2c_send_byte(I2C_WRITE_ADDRESS(slaveId));
/* send the register address */
i2c_send_byte(registerAddress);
/* signal a repeated start condition */
i2c_send_repeated_start();
/* send the read address */
i2c_send_byte(I2C_READ_ADDRESS(slaveId));
/* switch to receive mode but disable ACK because only one data byte will be read */
i2c_enter_receive_mode_without_ack();
/* read a dummy byte to drive the clock */
i2c_read_dummy_byte();
/* stop signal */
i2c_send_stop();
/* fetch the last received byte */
register uint8_t result = I2C0->D;
return result;
}
int i2c_read (uint8_t chip_id, uint8_t reg_addr, uint8_t* buffer, uint16_t len)
{
int status = 0;
/* send chip internal register address (pointer register) */
if (status == 0) i2c_send_start ();
if (status == 0) status = i2c_write_byte (chip_id << 1 | I2C_WRITE_OPER);
if (status == 0) status = i2c_write_byte (reg_addr);
if (status == 0) i2c_send_repeated_start ();
/* send again chip id before to switch to read mode */
if (status == 0) status = i2c_write_byte ((chip_id << 1) | I2C_READ_OPER);
if (status == 0) i2c_switch_to_read_operation(len > 1);
/* read specified number of bytes */
if (status == 0) {
while (len > 1) {
*buffer++ = i2c_read_byte (--len > 1);
}
}
i2c_send_stop ();
if (status == 0) *buffer++ = i2c_read_byte (false);
return status;
}
/**
* @brief Reads multiple 8-bit registers from an I2C slave
* @param[in] slaveId The slave device ID
* @param[in] startRegisterAddress The first register address
* @param[in] registerCount The number of registers to read; Must be greater than or equal to two.
* @param[out] buffer The buffer to write into
* @return 0 is successful, 1 if not
*/
static int i2c_read_registers_internal(register uint8_t slaveId, register uint8_t startRegisterAddress, register uint8_t registerCount, uint8_t *const buffer){
if(registerCount < 2)
return -1;
/* loop while the bus is still busy */
i2c_wait_while_busy();
/* send I2C start signal and set write direction, also enables ACK */
i2c_send_start();
/* send the slave address and wait for the I2C bus operation to complete */
i2c_send_byte(I2C_WRITE_ADDRESS(slaveId));
/* send the register address */
i2c_send_byte(startRegisterAddress);
/* signal a repeated start condition */
i2c_send_repeated_start();
/* send the read address */
i2c_send_byte(I2C_READ_ADDRESS(slaveId));
/* switch to receive mode and assume more than one register */
i2c_enter_receive_mode_with_ack();
/* read a dummy byte to drive the clock */
i2c_read_dummy_byte();
/* for all remaining bytes, read */
--registerCount;
uint8_t index = 0;
while (--registerCount > 0)
{
/* fetch and store value */
register uint8_t value = I2C0->D;
buffer[index++] = value;
/* wait for completion */
i2c_wait();
}
/* disable ACK and read second-to-last byte */
i2c_disable_ack();
/* fetch and store value */
buffer[index++] = I2C0->D;
/* wait for completion */
i2c_wait();
/* stop signal */
i2c_send_stop();
/* fetch the last received byte */
buffer[index++] = I2C0->D;
return 0;
}
