I am still trying to convert properly the Arduino MAX30105 driver to work with NRF52 and managed to come to somewhere... Everything works except the reading of the MAX30105 FIFO data (the data from the sensor).
I have troubles understanding how to do the requests they are doing with the Arduino Wire library using the NRF52 TWI.
Here is the arduino library part that I have trouble converting:
//Get ready to read a burst of data from the FIFO register
_i2cPort->beginTransmission(MAX30105_ADDRESS);
_i2cPort->write(MAX30105_FIFODATA);
_i2cPort->endTransmission();
//We may need to read as many as 288 bytes so we read in blocks no larger than I2C_BUFFER_LENGTH
//I2C_BUFFER_LENGTH changes based on the platform. 64 bytes for SAMD21, 32 bytes for Uno.
//Wire.requestFrom() is limited to BUFFER_LENGTH which is 32 on the Uno
while (bytesLeftToRead > 0)
{
int toGet = bytesLeftToRead;
if (toGet > I2C_BUFFER_LENGTH)
{
//If toGet is 32 this is bad because we read 6 bytes (Red+IR * 3 = 6) at a time
//32 % 6 = 2 left over. We don't want to request 32 bytes, we want to request 30.
//32 % 9 (Red+IR+GREEN) = 5 left over. We want to request 27.
toGet = I2C_BUFFER_LENGTH - (I2C_BUFFER_LENGTH % (activeLEDs * 3)); //Trim toGet to be a multiple of the samples we need to read
}
bytesLeftToRead -= toGet;
//Request toGet number of bytes from sensor
_i2cPort->requestFrom(MAX30105_ADDRESS, toGet);
while (toGet > 0)
{
sense.head++; //Advance the head of the storage struct
sense.head %= STORAGE_SIZE; //Wrap condition
byte temp[sizeof(uint32_t)]; //Array of 4 bytes that we will convert into long
uint32_t tempLong;
//Burst read three bytes - RED
temp[3] = 0;
temp[2] = _i2cPort->read();
temp[1] = _i2cPort->read();
temp[0] = _i2cPort->read();
I am trying to do this like this:
//Get ready to read a burst of data from the FIFO register
ret_code_t err_code;
uint8_t reg_write[1] = {MAX30105_FIFODATA};
err_code = nrf_drv_twi_tx(&m_twi, MAX30105_ADDRESS, reg_write, sizeof(reg_write), true);
APP_ERROR_CHECK(err_code);
//We may need to read as many as 288 uint8_ts so we read in blocks no larger than I2C_BUFFER_LENGTH
//I2C_BUFFER_LENGTH changes based on the platform. 64 uint8_ts for SAMD21, 32 uint8_ts for Uno.
//Wire.requestFrom() is limited to BUFFER_LENGTH which is 32 on the Uno
while (bytesLeftToRead > 0)
{
int toGet = bytesLeftToRead;
if (toGet > MAX30105_I2C_BUFFER_LENGTH)
{
//If toGet is 32 this is bad because we read 6 uint8_ts (Red+IR * 3 = 6) at a time
//32 % 6 = 2 left over. We don't want to request 32 uint8_ts, we want to request 30.
//32 % 9 (Red+IR+GREEN) = 5 left over. We want to request 27.
toGet = MAX30105_I2C_BUFFER_LENGTH - (MAX30105_I2C_BUFFER_LENGTH % (MAX30105_activeLEDs * 3)); //Trim toGet to be a multiple of the samples we need to read
}
bytesLeftToRead -= toGet;
//Request toGet number of uint8_ts from sensor
ret_code_t err_code1;
uint8_t m_sample[sizeof(toGet)];
while (toGet > 0)
{
sense.head++; //Advance the head of the storage struct
sense.head %= MAX30105_STORAGE_SIZE; //Wrap condition
uint8_t temp[sizeof(uint32_t)]; //Array of 4 uint8_ts that we will convert into long
uint32_t tempLong;
//Burst read three uint8_ts - RED
temp[3] = 0;
err_code1 = nrf_drv_twi_rx(&m_twi, MAX30105_ADDRESS, &m_sample, sizeof(m_sample));
APP_ERROR_CHECK(err_code1);
temp[2] = m_sample;
err_code1 = nrf_drv_twi_rx(&m_twi, MAX30105_ADDRESS, &m_sample, sizeof(m_sample));
APP_ERROR_CHECK(err_code1);
temp[1] = m_sample;
err_code1 = nrf_drv_twi_rx(&m_twi, MAX30105_ADDRESS, &m_sample, sizeof(m_sample));
APP_ERROR_CHECK(err_code1);
temp[0] = m_sample;My question is how can i do the line "_i2cPort->requestFrom(MAX30105_ADDRESS, toGet);" using the NRF52 TWI and is the "nrf_drv_twi_rx(&m_twi, MAX30105_ADDRESS, &m_sample, sizeof(m_sample));" that i am using correct replacement for the "_i2cPort->read();" in arduino?
What i get is constant number which is same for all three LED values:
<info> app: Red: 30840
<info> app: IR: 30840
<info> app: Green: 30840
Any help is welcome. Thanks in advance.
