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Hi Experts,
We are facing some issue with I2C ACK/NACK we are sending 3 byte in i2c line but it is sending only two byte:
second byte missing.
I2C bytes : 82 ,0,253
82(0x29) is the address of the slave device, It is not sending 0(Zero).
It is sending 82 and 253 only, Why?
Am i doing some mistake?
***
Thank you.
Regards,
Archie A.
Hi Archie,
I'm not familiar with TMP1075NDRLR but does your I2C waveform for reads conform to what is shown in TMP1075NDRLR datasheet.
In your code, I don't see you start with a slave address byte. Your first line starts with MAP_I2CMasterDataPut(I2C2_BASE, 0x00) which is writing data to the TX buffer. What is this for? Where are you starting a Slave Address byte for read like shown in the above timing diagram?
Below is an example reading from a I2C device.
Thank you, Charles.
For i2c init and salve address setup
void temp_sensor(void)
{
MAP_SysCtlPeripheralDisable(SYSCTL_PERIPH_I2C2);
MAP_SysCtlPeripheralReset(SYSCTL_PERIPH_I2C2);
MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C2);
MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOL);
MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C2);
MAP_GPIOPinConfigure(GPIO_PL1_I2C2SCL);
MAP_GPIOPinConfigure(GPIO_PL0_I2C2SDA); //I2C2 data PORT PL0
MAP_GPIOPinTypeI2C(GPIO_PORTL_BASE, GPIO_PIN_0); // PL0 is data
MAP_GPIOPinTypeI2CSCL(GPIO_PORTL_BASE,GPIO_PIN_1); // PL1 is clock
while(!MAP_SysCtlPeripheralReady(SYSCTL_PERIPH_I2C2)) // I2C2 peripheral ready
{
}
MAP_I2CMasterInitExpClk(I2C2_BASE, ui32SysClock, true); // I2C2 clock setup
MAP_I2CMasterSlaveAddrSet(I2C2_BASE, 0x48, true); // I2C2 address setup for slave
MAP_I2CMasterEnable(I2C2_BASE);
}
For read the slave.
void read_temperature()
{
uint32_t Board_temp[4];
MAP_I2CMasterDataPut(I2C2_BASE, 0x00); //slave register
MAP_I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_RECEIVE_START);
while(!MAP_I2CMasterBusy(I2C2_BASE))
{
}
while(MAP_I2CMasterBusy(I2C2_BASE))
{
}
Board_temp[0] = MAP_I2CMasterDataGet(I2C2_BASE);
MAP_I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_RECEIVE_CONT);
while(!MAP_I2CMasterBusy(I2C2_BASE))
{
}
while(MAP_I2CMasterBusy(I2C2_BASE))
{
}
Board_temp[1] = MAP_I2CMasterDataGet(I2C2_BASE);
MAP_I2CMasterControl(I2C2_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);
while(!MAP_I2CMasterBusy(I2C2_BASE))
{
}
while(MAP_I2CMasterBusy(I2C2_BASE));
System_printf("Btemp=%d %d", Board_temp[0],Board_temp[1]);System_flush();
}
First byte(0x91) is slave address
second byte should be (0x00) is slave register
Third byte should be first byte of temperature
fourth byte should be second byte of temperature
But i am getting some this wrong
Please find the attached file.
Regards,
Archie/Sumit
I don't think your waveform is conforming to the read sequence specified in the TMP1075 datasheet. Look at the waveform below for reading one byte of data from the sensor. In order to read, you need to provide the first frame to which is a slave address byte for WRITE direction. The second frame is to specify the register that you want to read from. The in the third frame you need to provide a slave address byte again for READ direction. The fourth frame is the data returned by the sensor device. In your waveform, I don't see the first two frames. I only see you start with frame 3 followed by three more reads. Can you show the first two frames.
