How can i use i2c4 on STM32H750B-DK?

[David Kim]

I'm testing i2c4 on STM32H750B-DK board with DS3231 but I think that i2c4 peripheral is not worked as i expected.

1. CubeMX settings

 - Only set SYS, RCC(HSE-Crsystal/Ceramic Resonator), USART3(115200 bps), I2C4(PD12: I2C4_SCL, PD13: I2C4_SDA)) after clear pinouts

2. CubeIDE

- After generating project from CubeMX, I worte below test code in main.c

uint8_t data;
uint16_t addr;
HAL_StatusTypeDef err;

printf("I2C bus Scanning...\r\n");
printf("==========================================================================\r\n");

for(addr = 0; addr < 0x80; addr++) {
  printf("%02X", addr);
  err = HAL_I2C_IsDeviceReady(&hi2c4, addr, 3, 100);
  if(err == HAL_OK) {
    printf(":found", addr);
  }else {
    printf(":%d", err);
  }
  printf( (addr%8)==7 ? "\r\n":"  ");
}

the result looks like abonamal. because DS3231 slave address is 0x57 but not found. 

and too many devices are detected. As i know Only 2 devices used i2c interface on this board.

==========================================================================
00:1      01:1      02:1      03:1      04:1      05:1      06:1      07:1    
08:1      09:1      0A:1      0B:1      0C:1      0D:1      0E:1      0F:1    
10:1      11:1      12:1      13:1      14:1      15:1      16:1      17:1    
18:1      19:1      1A:1      1B:1      1C:1      1D:1      1E:1      1F:1    
20:1      21:1      22:1      23:1      24:1      25:1      26:1      27:1    
28:1      29:1      2A:1      2B:1      2C:1      2D:1      2E:1      2F:1    
30:1      31:1      32:1      33:1      34:found  35:found  36:1      37:1    
38:1      39:1      3A:1      3B:1      3C:1      3D:1      3E:1      3F:1    
40:1      41:1      42:1      43:1      44:1      45:1      46:1      47:1    
48:1      49:1      4A:1      4B:1      4C:1      4D:1      4E:1      4F:1    
50:1      51:1      52:1      53:1      54:1      55:1      56:1      57:1    
58:1      59:1      5A:1      5B:1      5C:1      5D:1      5E:1      5F:1    
60:1      61:1      62:1      63:1      64:1      65:1      66:1      67:1    
68:1      69:1      6A:1      6B:1      6C:1      6D:1      6E:1      6F:1    
70:found  71:found  72:1      73:1      74:1      75:1      76:1      77:1    
78:1      79:1      7A:1      7B:1      7C:1      7D:1      7E:1      7F:1   

 Did i miss something? How can i resolve this problem?

[Johi]

Are you able to connect a scope to the bus?

If possible one with protocol analyzing capabilities?

[Pavel A.]

Consider that the LSB (R/W bit) is OR'ed by the ST library so 0x34 and 0x35 is the same device, and 0x70, 0x71.

[TDK · Accepted solution]

The HAL library expects you to provide the 7 bit address left-shifted. In other words, if you want to find the slave with 7-bit address 0x57, you need to pass 2*0x57 (0xAE).

You're only checking half of the addresses in your loop. You need to check up to 255.

[David Kim]

Thank you for the comment. I don't have it but i resovled this problem.

[David Kim]

I read about CR2 register value in datasheet. Slave address only used SADD[7:1] bits in 7bit address mode . Not used 0th bit. so I modified source code according to your comment.

err = HAL_I2C_IsDeviceReady(&hi2c4, addr<<1, 10, 1000);

Finally, I got the correct result like below.

$ I2C bus Scanning...
==========================================================================
00:1      01:1      02:1      03:1      04:1      05:1      06:1      07:1    
08:1      09:1      0A:1      0B:1      0C:1      0D:1      0E:1      0F:1    
10:1      11:1      12:1      13:1      14:1      15:1      16:1      17:1    
18:1      19:1      1A:found  1B:1      1C:1      1D:1      1E:1      1F:1    
20:1      21:1      22:1      23:1      24:1      25:1      26:1      27:1    
28:1      29:1      2A:1      2B:1      2C:1      2D:1      2E:1      2F:1    
30:1      31:1      32:1      33:1      34:1      35:1      36:1      37:1    
38:found  39:1      3A:1      3B:1      3C:1      3D:1      3E:1      3F:1    
40:1      41:1      42:1      43:1      44:1      45:1      46:1      47:1    
48:1      49:1      4A:1      4B:1      4C:1      4D:1      4E:1      4F:1    
50:1      51:1      52:1      53:1      54:1      55:1      56:1      57:found
58:1      59:1      5A:1      5B:1      5C:1      5D:1      5E:1      5F:1    
60:1      61:1      62:1      63:1      64:1      65:1      66:1      67:1    
68:found  69:1      6A:1      6B:1      6C:1      6D:1      6E:1      6F:1    
70:1      71:1      72:1      73:1      74:1      75:1      76:1      77:1    
78:1      79:1      7A:1      7B:1      7C:1      7D:1      7E:1      7F:1    

Thanks