I cannot get I2C work on stm32l476

[Peter Curtis]

Posted on January 19, 2018 at 21:59

Hi All,

First post on here and a newbie with the STM32 family of devices (I come from a PIC background - sorry about that)

I have just received my first STM32 board design back from the sub contractors and am having a little trouble and am hoping someone can point me in the right direction.

First of all, I'm using keil as the IDE/Compiler.  I have configured the micro using CUBE and am using the HAL libraries. 

My issue is that I cannot get I2C_MEM_WRITE or READ to work.

On the first use of > if(HAL_I2C_IsDeviceReady(&hi2c1, I2C_ROM, 1, 100) == HAL_OK)

I get an OK.  When I try a mem_write it fails (that is HAL_OK returns 0).

I have check my soldering and even shortened the i2c bus by truncating it immediately after the cat24c512 with a craft knife (and adding 2x10k resistors to vcc), but still no luck.

The device address (I2C_ROM) is defined as 0xA0.  I have tried playing with the timeout also.

I notice that in CUBE things like rise and fall time can be set - not idea what to set these to (didn't have to worry about that in the world of PIC).

Any pointers would be most appreciated.

Here is the code:-

uint8_t WriteConfigToI2C(void)

{

    char buffer[5] = 'TEST';

    uint8_t i;

  

  if(HAL_I2C_IsDeviceReady(&hi2c1, I2C_ROM, 1, 100) == HAL_OK)  //i2c address of eeprom = 0b1010000 = 0xa0

  {    

       HAL_UART_Transmit(&hlpuart1, (uint8_t*)'\r\nWrite', 7, 1000);   //(uint8_t*)'\r\nready'

       HAL_Delay(100);

    

      if(HAL_I2C_Mem_Write(&hi2c1, I2C_ROM, 0x00, 0xFFFF, (uint8_t*)buffer, strlen(buffer), 100) == HAL_OK)  // write       'buffer' to I2C mem

   

     {

          HAL_UART_Transmit(&hlpuart1, (uint8_t*)': OK', 4, 1000); // send 'OK' to uart if success

          HAL_Delay(100); // wait for eeprom to commit / finish

     

          // clear buffer

          for(i = 0; i < 50; i++)

         {

               buffer[i] = 0; 

         }

     

        // read the memory and write it back out on uart

     

       HAL_I2C_Mem_Read(&hi2c1, I2C_ROM, 0x00, 0xFFFF, (uint8_t*)buffer, 5, 100);  // read back eeprom and put into        'i2cBuffer'

          

        HAL_UART_Transmit(&hlpuart1, (uint8_t*)buffer, strlen(buffer), 1000);  // write 'i2cBuffer' to uart

     

    }

    else

    {

     HAL_UART_Transmit(&hlpuart1, (uint8_t*)': FAIL', 6, 1000);  // failed to write

    } 

  }

  else

  {

    HAL_UART_Transmit(&hlpuart1, (uint8_t*)'\r\nNotReady', 10, 1000);

  }

 

}

[Andrew Neil]

Posted on January 21, 2018 at 00:48

 a newbie with the STM32 ... I have just received my first STM32 board design back from the sub contractors

So have you first prototyped this on a Discovery or Nucleo or other Dev Board?

That should give you a working reference point ...

Have you scoped the pins to see what - if anything - is actually happening on the wires?

[Peter Curtis]

Posted on January 25, 2018 at 10:38

Hi Andrew,

Thank you for your response.  Yes.  I hooked SDA/SCL up to a scope and checked out the signals.  The rise looked a bit woolly, so I reduced the pull-ups to 1K. 

Above shows the trace when running the IsDeviceReady() on 0xA0 (the CAT24C512).

However, if I try to write to the device afterwards, It still fails to write.  Then the mem device appears to lock up - that is I get a not ready response if I try another IsDeviceReady().

Not quite sure where to go with this at the moment.  I have an I2C bus analyser on the way, maybe that will shed more light - but I've never had to use one in the 10years of my using I2C on other controllers.

thanks,

Peter

[Andrew Neil]

Posted on January 25, 2018 at 12:25

Can't your scope give you a screenshot directly?

Peter Curtis wrote:

Not quite sure where to go with this at the moment. 

Verify that scope waveform against the I2C spec.

• Is it a valid Start Condition?
• Is the slave address correct?
• is the R/W bit correct?
• does the Slave ACK?

Again, have you tried it on a known-good board (Nucleo, Disco, etc) with a known-good example for that board?

[T J]

Posted on January 22, 2018 at 04:10

this works for me,

after the cube is setup, I use blocking mode to send the frame.

the last line sends the data in blocking mode.

#define MCP4728_DacAddress 0x60 << 1

struct DacIIC {
 uint8_t DacTxBuffer[4];
 uint8_t DacRxBuffer[16]; 
};

 struct DacIIC MCP4728IIC;
 HAL_StatusTypeDef IIC_Response; 
 char channel;
 char use2xGain = false;
 char powerDownMode = false;
 char UseInternalVRef = false;
 int Dac_Value;
 
 channel = 0;
 Dac0_Value = (4096 * 1) / 5; // 1V
 MCP4728IIC.DacTxBuffer[0] = 0x40 | ((channel & 0x3) << 1);
 MCP4728IIC.DacTxBuffer[1] = ((uint8_t)UseInternalVRef << 7) | ((powerDownMode & 0x3) << 5) | ((uint8_t)use2xGain << 4);
 MCP4728IIC.DacTxBuffer[1] |= (Dac0_Value & 0x0f00)>>8; 
 MCP4728IIC.DacTxBuffer[2] = Dac0_Value & 0xff;
 //DAC_IIC.write(DAC_ADDR + (Dac_Address << 1), buf, 3, 0) == 0; //mbed
 
 IIC_Response = HAL_I2C_Master_Transmit(&hi2c1, MCP4728_DacAddress, &MCP4728IIC.DacTxBuffer[0], 3, 10);�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

[T J]

Posted on January 25, 2018 at 22:42

'it fails to write'

can you read data and status from the flash CAT24C512 ?

I suggest that you stop using : HAL_I2C_IsDeviceReady

and use something like my suggestion above :

HAL_I2C_Master_Transmit(&hi2c1, MCP4728_DacAddress, &MCP4728IIC.DacTxBuffer[0], 3, 10);
HAL_I2C_Master_Receive(I2C_HandleTypeDef *hi2c, uint16_t DevAddress, uint8_t *pData, uint16_t Size, uint32_t Timeout)

[Peter Curtis]

Posted on January 26, 2018 at 16:27

Hi TJ,

Thank you for your reply - but it doesn't look possible to use this function with a memory device as I need to set the internal address to write to, before writing data.

Many thanks,

Peter

[T J]

183018CGIL3