I2C communication between nrf52 and stm32

RE: I2C communication between nrf52 and stm32

Duncan Xu — Thu, 20 Sep 2018 16:03:23 GMT

At first, I didn't add external pull-up resistors since I thought there are built-in pull-ups and it should be good. But after I added two 10k resistors to the SCL and SDA, it works. Thank you for your help, Martin.

RE: I2C communication between nrf52 and stm32

MartinBL — Thu, 20 Sep 2018 13:10:18 GMT

Can you upload some screenshots that compare similar data transfers between the STM32 and the nRF52 and between the STM32 and the other device?

RE: I2C communication between nrf52 and stm32

Duncan Xu — Wed, 19 Sep 2018 22:40:08 GMT

Thanks, Martin. Yes, but when I test the STM32 code with another I2C device and it works, so I couldn't sure whether the STM32 or nRF52 causes the problem. The STM32 and nRF52 are using the same supply voltage and share the same ground. I set the STM32 to receive one byte for each time and nRF52 prepares one byte too.

RE: I2C communication between nrf52 and stm32

MartinBL — Wed, 19 Sep 2018 14:21:28 GMT

From the oscilloscope, I can see the stm32 sent the start condition, stop condition, the slave address, the write or read command; the nrf52 sent the ACK to appropriate positions and data.
So an Arduino can read the nRF52 just fine, and the nRF52 both acknowledges your commands and transfers data to the STM32? Doesn't all this indicate a bug in your STM32 code? Maybe it is expecting a certain number of bytes, but not getting as many?

Or it could be an issue with the voltage levels. Are both the STM and the nRF52 running on the same supply voltage? And do they have common ground?