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Reading Registers on AD7172-4

Question asked by bernhard.bender on Nov 8, 2016
Latest reply on Jan 28, 2018 by j0hnny

Hello everone.

 

I have connected the EVAL-AD7172-4SDZ board to the SPI interface on a STM32F405 board. Writing to registers in the ADC seems to work fine, e.g. I can start a conversion in single conversion mode, set the ADC into standby mode or turn on an LED on the eval board by activating the PDSW bit in the GPIO register (0x06).

 

However, reading by any of the registers does not return the values as expected. Especially the ID register (0x07) does not return 0x205x as shown in the data sheet, but 0x0077 instead.

A screen shot showing the SPI signals is attached.

 

The code I use is very similar to the No-OS package on github.

 

Any hints about getting the chip to return the correct read data will be greatly appreciated.

 

The same problem applies to other registers in that writing them seems to word while reading back does not give the expected results.E.g. I write 0x1f00 to SETUP0 (0x20) and read back 0x1e01.

 

Btw I am referring to the AD7172-4 data sheet in Rev. A.

 

Thanks a lot.

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