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ADS1255: ADS1255 initializing errors

Part Number: ADS1255

Hello. In my application ADS1255 works with my microcontroller throught shrort cable with 200 Ohm resistors on data lines:

And i cant correcntly configure it via SPI. In different cases different registers may configures differently. And it is not rigidly dependent on specific external conditions, which complicates debugging.

For example I set low frequency SPI and try to set data rate to 2000 Hz. And oscilloscope does not show any problems with fronts, but DRDY toggling friquency still stay 30000 Hz. This is oscillogram of SCL and MOSI:

What i did wrong?

Analog and digital power on ADC is good. I checked it.

  • HI Egor,

    Your scope shots did not come through in your last post, can you please add them again? It usually helps to put them in a Word document or PDF and attach that file

    Can you please send a schematic as well so we can review? This will help in the debugging process.

    And if you have a logic analyzer, that would also be helpful to be able to see all the SPI communication lines simultaneously (DOUT, DIN, SCLK, DRDY)

    We generally recommend a series resistance of 30-50ohms on the communication lines, so that could be one thing to try while we wait for you to provide more information.


  • Okey, try again. This is the scope:

    This is the scheme:

  • HI Egor,

    Thanks for posting these images and the schematic. I see that you have a split ground plane with an inductor between DGND and AGND. We generally recommend a solid ground plane for best performance, you can read more about why here:

    I also see an inductor between the DVDD supply voltage and the DVDD voltage applied to the device. I would suggest removing this as well and see if you get better performance.

    Finally, looks like you are getting a lot of noise on the DIN signal, reducing those series resistors might help. Do you have a logic analyzer to show the 4x SPI signals at once (DIN, DOUT, SCLK, DRDY)? It will be hard to know what is going on without being able to see the SPI input to the ADC and the corresponding output.