Not able to get acceleration data from Adafruit LSM6DSO32 with STM32 Nucleo F446RE

[atamby187]

Hi, 

I have been trying to get acceleration data from an Adafruit LSM6DSO32 with the STM32 Nucleo board F446RE via i2c. I used the STMems_Standard_C_drivers  (GitHub - STMicroelectronics/lsm6dso32-pid at 308cf0e4de0db190c453f3e211b0c40990f1f39b) in order to set the IMU properly. I also use the STM32CubeIDE app to programme the MCU. 

Despite many efforts, the Nucleo board is not able to recognise the IMU (I checked that a test buffer that prints whether the device is recognised using the whoami register (please refer to the 7z folder attached)), though I double checked the slave address of the components and the connections (please see attached image (IMG_0605.jpg). Could you please help me solve that problem? 

You can find enclosed a copy of the STM32CubeIDE project. 

Best regards, 

Audric

[Federica Bossi]

Hi @atamby187 ,

Welcome to ST Community!

I see two possible issues in your code:

1. the who_am_i is defined as LSM6DSO32_ID in the drivers while you use another value
2. Since you have not connected pin D0 you can try the i2c address LSM6DSO32_I2C_ADD_L

[atamby187]

Hi Frederica Bossi, 

Thank you for helping solve this problem.

The problem was with the i2c address of the Adafuit IMU which is 0xD4 (0x6A << 1) and not 0x6A as seen on Adafruit website.

Best regards, 

Audric

[Andrew Neil]

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@atamby187 wrote:

The problem was with the i2c address of the Adafuit IMU which is 0xD4 (0x6A << 1) and not 0x6A as seen on Adafruit website.

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An I2C address is just 7 bits, so Adafruit are correct to say that the I2C address is 0x6A = 110 1010

The value 0xD4 is made up of the address plus the R/W bit: 1101 0100 = 0xD4

This is a frequent cause of confusion:

https://www.avrfreaks.net/s/topic/a5C3l000000UXMPEA4/t142031?comment=P-1150738#:~:text=The%20discrepancy%20between%20talking%20of%20I2C%20addresses%20as%207%20or%208%20bits%20is%20very%20common%20indeed%20in%20software%2C%20tutorials%2C%20articles%2C%20and%20device%20datasheets.

 

As shown in the ST datasheet, the value 0xD4 is the "SAD+R/W" - ie, Slave ADdress plus the R/W bit: