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ADUCM355 Square Wave Voltammetry example on eval board not biased correctly

Hello all,

Thanks in advance for any help and guidance! I'm having trouble getting the demo to work as expected...

I'm running the example code with a 10K resistive load from WE0 to RE0/CE0. RE and CE are shorted together. The connections are being made to the chemical sensor sockets on the eval PCBA. The setting have a negative ramp from -0.2V to -0.4V and VzeroStart/VzeroPeak are set to +1.3V.  When I put a scope probe on WE0 and RE/CE0 I see the ramp and square wave on both probes at virtually the same bias levels. I'd expect the reference voltage to hold at 1.3V and RE to ramp down from there to create the required bias.  I measured for any shorts across the connectors and all measurements look correct.  Am I missing something fundamental in the settings or configuration maybe?

When I use the same settings and passive load with the EmStat/PalmSens (same chipset) the waveforms looks like this (Channel 1, Channel 2, and the diff the electrochemistry sees [CH1-CH2]). Which is correct.

But on the eval board channel 1 and 2 are both the ramp (downward in my case).

Thanks!

Marty