AMS5812 I2C Sensor Holding I2C3 Bus on STM32F407G-DISC1

[asking]

I am trying to implement LCD and AMS5812 Sensor on I2C3 Bus,

But AMS5812 I2C sensor is holding the I2C bus and preventing further scanning STM32F407G Discovery board.

  /*-[ I2C Bus Scanning ]-*/
	     HAL_UART_Transmit(&huart2, (uint8_t *)StartMSG, sizeof(StartMSG), 10000);
	     for(i=1; i<128; i++)
	     {
	         ret = HAL_I2C_IsDeviceReady(&hi2c3, (uint16_t)(i<<1), 3, 5);
	         if (ret != HAL_OK) /* No ACK Received At That Address */
	         {
	             HAL_UART_Transmit(&huart2, (uint8_t *)Space, sizeof(Space), 10000);
	         }
	         else if(ret == HAL_OK)
	         {
	             sprintf(Buffer, "0x%X", i);
	             HAL_UART_Transmit(&huart2, (uint8_t *)Buffer, sizeof(Buffer), 10000);
	         }
	     }
	     HAL_UART_Transmit(&huart2, (uint8_t *)EndMSG, sizeof(EndMSG), 10000);
	     /*--[ Scanning Done ]--*/
	     HAL_Delay(1000);

AMS5812 sensor is working on 5V and i2c LCD is also working on 5V. i am using 5V to 3V level shifter as below.

first time i2c Scanning code detect lcd address as 0x27 and then blank.

Expected 0x27 and 0x78 

I have tried using 3.1K pull up resistors but no benefit on both the sides of level shifter.

Please advise where i could be wrong ?

[Johi]

Your converter also needs supply voltage and GND

LV = 3V, HV=5V, GND = GND

[Issamos]

Hello @asking 

Can you add your code to take a look on it. Also, can you try using just the LCD.

Best regards.

II

[asking]

Yes, only LCD works fine. also other I2C Devices like SM Pressure sensors works fine. Only problem is AMS5812 when i put on bus. No further scanning only - - - - .

Core is simple I2C Discovery code. i have enabled I2C3 with 400000HZ Fast Mode.

[asking]

Yes i have connected LV to 3V, HV to 5V and GND to System GND Common for all systems.

[Issamos]

Can you try using another I2C 

[asking]

Yes, i will try another i2c bus and update.

[Foued_KH]

Hello @asking , 

The silver dot on the AMS 5812 marks the location of Pin 1. The AMS 5812 pinout is:

• Pin 2: Ground
• Pin 4: SDA
• Pin 5: SCL
• Pin 7: VCC, this should be a 4.75V to 5.25V power source.

4.7 kOhm resistors should be used as pullups on SDA and SCL, these resistors should pullup with a 5V source.

Foued

[asking]

Yes i have double checked the connection. now trying with scope on I2C Bus....

[asking]

SCL / SDA on Scope. Below Observations.

With AMS5812 Sensor, Peak is curved.

Yellow is SDA and Violet is SCL

Without AMS5812 Sensor. I2C Scanner works fine.