How to implement repeated start for HAL_I2C_Mem_Read and HAL_I2C_Mem_Write?

[FD.1]

Hello,

i want to communicate with an AD7998, to convert 8 analog to digital channels. The communication i use is I2C. I am using the HAL library.

According to the adc manual i need a repeated start, after writing to the address pointer byte. So i had tried to use HAL_I2C_Mem_Read, but that isn't working.

Are there other functions in the i2c HAL library to implement a repeated start?

Thanks.

[Pavel A. · Accepted solution]

Yes, HAL_I2C_Mem_Read does a repeated start. If it doesn't work, check parameters. Use a logic analyzer.

-- pa

[Piranha]

So, your approach is, if something doesn't work, then:

1. Don't fix the actual problem. Instead try something other.
2. Choose randomly one feature (repeated start) and try to find a "solution" for it.

And, as you can see, that careless approach doesn't work... Instead there are two other approaches that actually work - either you carefully check everything or take an oscilloscope or logic analyzer and debug it.

[FD.1]

Hi,

thanks for your reply. It works now. My ADC just didn't transfer the register values correctly. I disconnected it from the supply for a while, now it works as it should.

@ Pavel A. Good to know that, thank you.