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AD7381-4: Changes in the configuration register shows no effect / soft reset resets register

Category: Hardware
Product Number: AD7381-4

I am using the AD7381-4  ADC with a STM32F4 microcontroller. The end goal is, to use quad SPI to get all the data I need.

At the moment, I try to communicate with the ADC using SPI only.

I am able the read and write the configuration register.

But it seems, that the changes I've made in the configuration register show no effect.

Here are some measurement I've done on the data lines:

Channel 0 is the CS line

Channel 1 is the SPI clock (SCLK)

Channel 3 is the MOSI line (SDI)

Channel 2 is the the MISO line (SDOA)

Channel 4 is the SDOB line

Hard reset and config register read.

Write to the register (enable 1-wire conversion in configuration register 2).  Reread the configuration register.

Initiate a soft reset. A nop command was send beforehand.

register read after soft reset. As you can see, the register have been reset.

Finally. Reading the ADC value.

As you can see in my measurement, I still get data on both SPI lines (as 2-wire conversion is the default value) after changing to 1-wire only.

I've tried to do a software soft reset, to see if that helps. But the soft reset also resets all the registers (according to the datasheet it shouldn't).

 I also tried to change the baudrate but with no different outcome.

Any pointer in the right direction is apprichiated.


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