XADC on CW305 reads zero Kelvin?


I am using a CW305 with an xc7a100t stand-alone and I am trying to read chip temperature and voltages via XADC (which I have successfully done on other Boards like Digilent Arty and Basys3).

However, I didn’t get it to work in a MicroBlaze system on CW305: the Temperature, VCCINT, VCCAUX, and VCCBRAM registers always read 0.

Next, I tried reading XADC via JTAG with no bitstream programmed into the FPGA in Vivado – with the same results (left hand side). For comparison, on an unprogrammed Arty-35T I can successfully read the chip temperature (right hand side).

SW2 was set to “USB” (111) in this screenshot, but changing it to JTAG (“101”) did not make a difference.
I used a Xilinx USB Platform cable to connect to JTAG.

Am I missing something?

Edit: I am using Vivado version 2019.1

You’re not missing anything - unfortunately the XADC isn’t functional on the CW305 because the required VCCADC and GNDADC pins were left unconnected (likely due to routing limitations).

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OK, thanks for confirming.