Unable to Communicate with ADS7038 ADC over SPI

[Avid]

Hello,

I am having issues communicating over SPI with an external ADC the ADS7038. I am using an STM32H750VB and sourced the code from github (precision-adc-examples/devices/ads7038 at main · TexasInstruments/precision-adc-examples). I am unable to read data from the ADC when it is connected to a thermocouple and only get a return of 0. I have tried reading from individual registers but have been unable to return a value. The STM32 pins all have correct continuity, but the ADS7038 is difficult to probe since it has a QFN package. I was able to get a signal on SCK and MOSI but MISO was just high. SPI is set as Full-Duplex master using CS pins to enable with a Baud rate of 2 Mbits/s. Attached is the entire code but also here are some screenshots of the main programs used to communicate SPI and read from the ADC. Any ideas for other things to try for debugging? 

 

 

 

 

[Andrew Neil]

Please see How to insert source code - not as screenshots.

 

So have you used a logic analyser on the SPI to see what's actually happening on the wires.

Does that match the requirements stated in the TI datasheet?

If it looks OK, present it to TI for their opinion:

https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum

 

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@Avid wrote:

the ADS7038 is difficult to probe since it has a QFN package.

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That's why it's always best to start by using a dev kit and/or breakout boards.

Or design your custom PCB with test points to access critical signals

[Avid]

Update, I noticed there was a schematic error with pin 8 DECAP being connected to 3V3 when it is only supposed to be connected to a capacitor that connects to GND, likely damaging the chip.