Zedboard Sampling negative signal and ADC Specs

[mosambers]

Hello,
 
is the ADC of Zedboard able to sample negative signals?
 
And what are the specifications of the ADC built in?
 
Thank You!
 
Best regards

[jpeyron]

Hi @mosambers,

The input needs to be 0-1V. It does not work with negative voltages. The xadc is a Dual 12-Bit 1 MSPS Analog-to-Digital Converter. Here is the 7 Series FPGAs and Zynq-7000 All Programmable SoC XADC Dual 12-Bit 1 MSPS Analog-to-Digital Converter User Guide.  i would suggest to also look at the reference manual here as well as this forum thread here which has a working zynq xadc project as well as information on how to connect to the xilinx xadc header if you are planning on using flywire connections. 

cheers,

jon

[mosambers]

Thank you Jon!

But should I not be able to measure negative voltages in bipolar mode?

The range is - 0.5 V - + 0.5 V.

[jpeyron]

Hi @mosambers,

Unfortunately, As far as I can see for the user guide here based on pages 31 and 32 the voltages still need to be positive. Second to last paragraph on page 31 states "All input voltages must be positive with respect to analog ground (GNDADC)." On page 32 it explains further the + and - .5 volts with the common mode voltage should be .5 volts. 

cheers,

Jon