Posted on September 17, 2015 at 13:36I am using STM32L152 Nucleo (Nucleo L152RE) with ALS sensor connected to it.ALS sensor has a 16 bit data register containing both MSB and LSB .
Below is the register Map
0x04 15:8 MSB Data of whole ALS 16bits
7:0 LSB Data of whole ALS 16bits
Read :
S-Slave-Address-Wr-
A-Command-Code-
A-DataLSB-
A-DataMSB-
A-P
Write :
S-Slave-Address-Wr-
A-Command-Code-
A-S-Slave-Address-Rd-
A-Data LSB-
A-Data-MSB-
A-P
where :
S-Start
P-Stop
A-Ack
Below is the code Which I am using to read the registers MSB and LSB but I am always getting MSB as 0xFF while LSB shows some data which I believe is correct.
union
{
uint8_t ubuff8[2];
uint16_t ubuff16;
} buffer;
uint8_t const length = 2U;
// Do a block read of sensor data
status = als_sensor_read_raw_register(0x04, buffer.ubuff8, length);
uint als_sensor_read_raw_register(uint8_t const register_address,uint8_t * buffer,uint8_t length)
{
als_buffer[0] = register_address; //0x04
pBuffer = als_buffer;
uint8_t len = 1;
if ((2 == length))
{
if( HAL_I2C_Master_Transmit(&hi2c1, ALS_ADDRESS_8_BIT, (uint8_t*)pBuffer,len, 1) == HAL_OK)
{
if( HAL_I2C_Master_Receive(&hi2c1, ALS_ADDRESS_8_BIT, (uint8_t*)buffer,length, 1) == HAL_OK)
{
status = true;
// data1 = buffer[0]; //for debugging - shows correct data
// data2 = buffer[1]; //for debugging - shows 0xFF always
}
else
{
status = false;
}
}
}
}
I think the reason for this is The smt32l1xx library in the HAL_Transmit is sending a stop in the library and I am using the same Transmit for both read and write
/* Wait until TXE flag is set */
if(I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_TXE, RESET, Timeout) != HAL_OK)
{
return HAL_TIMEOUT;
}
/* Generate Stop */
SET_BIT(hi2c->Instance->CR1,I2C_CR1_STOP);
/* Wait until BUSY flag is reset */
if(I2C_WaitOnFlagUntilTimeout(hi2c, I2C_FLAG_BUSY, SET, Timeout) != HAL_OK)
{It will work for write but not for multibyte read .Am I correct?.Can some one please review this and tell me what I am doing wrong here.How can I read the 16 bit register(containing both LSB and MSB data) of the Sensor in STM32l152 or STM32 Nucleo.With the same code Sensor having different 8 bit LSB and MSB data register I can read both the MSB and LSB data correctly.
Please assist.
Thanks in advance
Rp
#stm32-nucleo #nucleo #stm32l152
