ADS1256: ADS1256

Hi Hossein,

Can you post your schematic and describe in detail the issues that are occurring? The ADS1256 should work given an 8 MHz clock and 2.5 V reference voltage, so we will have to dig deeper here.

-Bryan

I can't read or write registers.

Hi Hossein,

Have you checked that your clock is operating properly and that the supply voltages are powering up correctly? We don't usually recommend ferrites on the supplies, unless you have sufficient bulk capacitance near the device. Even then, ferrites can choke the supply voltages during times of high current demand, causing supply droop.

Can you monitor DRDY to see if the device responds after initialization?

Can you let me know anything else that you have tried to fix your issue?

-Bryan

yes, I debugged drdy and it's ok.

No, I didn't test clock, but I know that when I did work with analog device ic, read and write registers is done witout clock and clock only need for analog section.

also I can see raw data when debugging, but data isn't true and time is varying.

Hi Hossein,

The ADC needs a clock signal to operate properly, so when you said you could not read or write registers I assumed there was either a clocking or supply issue such that the ADC wouldn't work at all.

But it sounds like you are getting data out of the ADS1256, it is just not correct data - is that true? Can you please explain what you mean by "data isn't true"? Do you have scope / logic analyzer shots that show your data output?

I would appreciate as much detail as possible

-Bryan

I'm using ST microcontroller and debugging in keil. I can see data on spi port, but can't do any change on registers. every thing is in default mode. The output data isn't correct. when connected to 5 volt, one time show 4.96 and one time show -0.04. sometimes show 2.5 volt ( I convert raw data to voltage).

In schematic you can see that I connected led to one gpio pins, but I can't do any change in it's register.

Hi Hossein,

Can you send scope or logic analyzer shots of your SPI communication lines? It would be helpful to see what is happening on CS, DOUT, DIN, etc., since this seems like a communication issue.

Have you tried issuing the SDATAC command first after powerup? If the device is somehow in RDATAC mode it will ignore any other commands.

-Bryan

Thank, my setup is in my lab. As soon as possible I send you the results.

Thanks a lot.