STEVAL-STLKT01V1 Sensor Tile connect to I2C device

[Jeremy Wong]

Posted on January 21, 2018 at 21:54

I have a 

STEVAL-STLKT01V1 Sensor Tile. I want to add additional sensing capabilities and was wondering how to add a peripheral that communicates over I2C? Are there any firmware examples of how to do this?

#stm32l4-hal-i2c

[Andrew Neil]

Posted on January 22, 2018 at 11:40

From UM2101, ''Getting started with the STEVAL-STLKT01V1 SensorTile integrated development platform'':

http://www.st.com/resource/en/user_manual/dm00320099.pdf

  

See: 

http://www.st.com/en/evaluation-tools/steval-stlkt01v1.html

 

Just looks to be a standard I2C connection - so any of the STM32 I2C examples should do?

[Jeremy Wong]

Posted on January 22, 2018 at 16:47

Thanks Andrew for your reply. I was looking at the basic I2C_TwoBoards_ComPolling example from STM32CubeL4 firmware examples but couldn't get it to work. Can you confirm some of the steps?

I2C_ADDRESS - From what I was reading, this should be bit shifted to the left to go from a 7-bit address to 8-bit left justified address? (e.g. I want slave with address 0x04, I would set this as 0x08?)

I2C_TIMING - Not sure how this is calculated so I've been going with the default of 0x00D00E28 from the example. I want the standard 100kbits/s clock rate.

I kept the I2C configurations from the example the same except changed it to 7-bit addressing mode

I2cHandle.Instance = I2Cx;

I2cHandle.Init.Timing = I2C_TIMING;

I2cHandle.Init.OwnAddress1 = I2C_ADDRESS;

I2cHandle.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;

I2cHandle.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;

I2cHandle.Init.OwnAddress2 = 0xFF;

I2cHandle.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;

I2cHandle.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;

After that, defining my transmit and receive buffers, I call

HAL_I2C_Master_Transmit(&I2cHandle, (uint16_t)I2C_ADDRESS, (uint8_t*)aTxBuffer, 3, 10000);

HAL_I2C_Master_Receive(&I2cHandle, (uint16_t)I2C_ADDRESS, (uint8_t *)aRxBuffer, 6, 10000);

However, HAL_I2C_Master_Transmit returns HAL_ERROR. I've added 10k resistors to the SDA and SCL lines to pull it up to 5V.

Any ideas what could be going wrong? Thanks.