CN-0376(Channel-to-Channel Isolated Temperature Input (Thermocouple/RTD) for PLC/DCS Applications)

Hi raj60 ,

I have moved this thread here (+) Q&A - Reference Designs - EngineerZone (analog.com). Someone from the community should be able to assist you in your queries.

Regards,

JC

Hi raj60 ,

The first step in debugging this is to validate hardware connections, power integrity, and signal integrity. The 0x00 device ID and -2.5V reading suspiciously point to all zeros on the SPI MISO line, all the time, which is a symptom of either no power to the AD7124s, or lack of connectivity for some other reason. Can you provide:

• A detailed connection diagram to the board, showing all power, ground, and digital signal connections.
  • Are you using the PMOD connectors? If so are you using only one of them? And if only one of them, is the other CS signal tied high to disable that channel?
• Photographs of your setup - this is often extremely valuable for identifying connectivity and integrity issues
• If possible, oscilloscope shots of all signals. The signals on the isolated side of the ADUM1441s are most important, but it does not look like they are easy to probe. Perhaps easiest is directly at the ADUM1441 pins, using a sharp oscilloscope probe.
  • Also a hint for probing isolated circuits for the purpose of debugging - it is often convenient to short all grounds together, so that the oscilloscope probes can be grounded to a single node while probing signals on both sides of the barrier.

It will probably be another engineer more familiar with this project that responds, but this will be helpful for them as well.

-Mark

Thank for your reply,  I am using the single channel these are connection pinouts 

cn0376(ad7124-4 bcpz)   ------------- stm32 nucleo l476RG

CS                                      -         D6(GPIO_OUTPUT made it as cs)

SDI                                     -         D4(SPI1MOSI)

SDO                                   -        D5(SPI1MISO)

SCLK                                  -       D3(SPI1_SCLK)

VCC                                    -      (3.3V)

DGND                              -            GND

PWR_SEL jumper connected to the EXT , through P3 applying the 9V  adapter (in the wiki note they mentioned that System is powered using terminal block P3 (input range:+5.5V to +36V DC)).Communications. I am connecting the RTD  in 3 wire mode.(Connect RTD wires to AIN+, AIN- and RETURN terminals, Short terminals IEXC and AIN+).

Another ch2-PMOD not connecting to nucelo board. . now as per you suggestion I did the another channel pmod cs pin make it as high. but i am getting the same device id as zero,

in the communication register initially I am writing the value as 0x45, I am trying to get the device id from the register but it is giving zero, can you please suggest me to find the data frame to read the device id of ad7124-bcpz.

Best Regards

Raj

Thanks for your reply , i have checked with XILINIX nexys DDR FPGA evolution  board, I am sharing the screenshots of ILA(integrated logic analyzer). to read device id we are sending the 0x45 value through spi and extra clock pulses to read the data from adc, but is giving 0x00. i have made the connections of another chip select connected to logic high. 

MaryMc or JellenieR  ,

Does the SPI mode look correct?

-Mark

Hi, 

Have you probe the ADC if it is powered up correctly? Can you check the IOVDD and AVDD pin if it is at a valid voltage level (i.e. 3.3V)? 

I was wondering if you can just pull /CS low, stop communicating with the device and just probe the /DRDY pin to see if the pin is pulsing at correct ODR.

Thanks,
Jellenie