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ADS1015 and PCA9548A

Karl Miller
Prodigy 10 points
Other Parts Discussed in Thread: ADS1015, PCA9548A

TI,

We are attempting to use your ADS1015 ADC thru your PCA9548A I2C Multiplexer.

However, I cannot get this to work on our ST Micro STMM32H processor. But we do have a working Arduino example.

I have attached traces for each.

We tried to make the I2c traffic as close to the Arduino traffic as possible.

We recognize that the ADS1015 requires a delay after a request for conversion, and originally had a write to 0 on the ADS then a 7 ms delay. But our I2C controller seems to put a write to 0 in every read. So we removed the write to 0 before the delay as the (working) Arduino code didn’t have that.

The Arduino is getting proper data back thru the ADS1015, but the ST Micro is getting all zeros back.

Please Advise.

Thanks!

 

  • 0
    TI__Mastermind 22950 points

    Hi Karl,

    Do you have a schematic you can share? I will look through the images you provided and get back to you if I need anything else. 

    Regards,

    Aaron Estrada

  • 0 in reply to Aaron Estrada
    TI__Mastermind 22950 points

    Hi Karl,

    Taking a closer look at the I2C transactions, I don't see a full write to the config register on the ST Micro I2C transaction. Only 8 bits (0xC4) are being written. Why are the other 8 bits not written? I am also curious what the I2C writes are with the address 0x70. Can you elaborate on this?

    If you can also provide the I2C read register transaction, that would be great. There seems to be acknowledgements coming from the ADC so I don't think there is any timing issue. Getting a full I2C transaction would definitely help here. 

    Regards,
    Aaron Estrada