TMP102 Configuration Register Read/Write fail

[rasem]

I need help to setup TMP102 alarm function. My board is NUCLEO-F439ZI

Reading the temperature is working fine.

uint8_t TMP102_ADDR = 0x48 << 1;

uint8_t REG_TEMP = 0x00;

uint8_t buf[12];

buf[0] = REG_TEMP;

ret = HAL_I2C_Master_Transmit(&hi2c2, 0x90, buf, 1, 10);    // OK

ret = HAL_I2C_Master_Transmit(&hi2c2, 0x90, 0x00, 1, 10);   //OK

ret = HAL_I2C_Master_Receive(&hi2c2, 0x90, buf, 2 , 10);    //OK

reads the temperature correctly. Buf[0] and buf[1]has correct temperature data.

I am trying to setup the alarm function. Reading/writing the Limit registers are failing.

Datasheet states that Thigh=80C, and Tlow=70C. After Reset.

I am reading the Thigh registers, with the following code:

uint8_t reghi = 0x03;

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, reghi, 1, 10); // fail

is sending 0x00 on reghi. I verified by scope.

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, 0x03, 1, 10);  //fail     

it is sending 0x00 to configuration register.

The only way to send the right value accomplished by:

Unit8_t reghi = 0x03;

buf[0] = reghigh;

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, buf, 1, 10); OK.

Sending 0x03 to select the Thigh register. Verified by scope.

Now I want to read the value of Thigh.

ret = HAL_I2C_Master_Receive(&hi2c2, TMP102_ADDR, buf, 2 , 100);

The value in buf[0] = 0x00;

The value in buf{1] = 0x00;

I verified it in Debug mode.

The same problem when I write two bytes to Thigh and read it back

It gives 0x00 for both bytes.

If anybody tried to set the alarm successfully in TMp102, please help.

Thanks,

Rasem

[Tesla DeLorean]

Yeah, because it want a POINTER, the address of variable, and not the number/constant itself..

uint8_t reghi = 0x03;

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, reghi, 1, 10); // fail

is sending 0x00 on reghi. I verified by scope.

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, 0x03, 1, 10);  //fail     

it is sending 0x00 to configuration register.

The only way to send the right value accomplished by:

uint8_t reghi = 0x03;
ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, (void *)&reghi, 1, 10); // pass via pointer

[rasem]

Hi Tesla DeLorean,

Thank you very much for your quick reply. It was great. I am able to read the High Temperature setting of

80C correctly.

I still need your help setting my own limits:

The following did not work.

uint8_t reghi = 0x03;

uint8_t  temphi[2];

uint8_t lowlimit [2];

temphi[0] = 0x1A;

temphi[1] = 0x00; // set high temp alarm at 26C.

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, (void *)&reghi, 1, 10); //OK

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, (void*)&temphi,2, 100);

ret = HAL_I2C_Master_Receive(&hi2c2, TMP102_ADDR, lowlimit, 2 , 100);

// reads lowlimit[0]=0x00, lowlimit[1]=0x00

Coffee on it's way.Thanks.

Rasem

[padawan · Accepted solution]

Hi Rasem

try this:

change 

temphi[0] = 0x1A;

temphi[1] = 0x00; // set high temp alarm at 26C.
to 
temphi[1] = 0x1A;

temphi[0] = 0x00; // set high temp alarm at 26C.

better

uint8_t temphi[3]= {0};
temphi[0] = 0x03; // register
temphi[1] = 0x00; // HiByte
temphi[2] = 0x1A; // LowByte

ret = HAL_I2C_Master_Transmit(&hi2c2, TMP102_ADDR, temphi,3, 100);

Hint: An array is always passed as an address.

hth

padawan

[rasem]

Hi Padawan.

Great solution. It is working now after sending 3 bytes togther.

Thank you very much.

Rasem