How to convert cnt to voltage in PID application?

[tom.zhang]

Hi

I'm starting to use the PID application in Red Pitaya. However, the PID set point and parameters use this bizarre unit cnt. How do I convert cnt to voltage or is it equivalent to voltage? This information is very important when assigning the set point so does anyone has any ideas? I couldn't find it on Red Pitaya wiki.

Thanks

[Nils Roos]

The conversion of pid setpoint voltage to cnt value is the same as for the fast analog inputs, see for example osc_fpga_cnv_v_to_cnt() and osc_fpga_calc_adc_max_v(). They take the calibration values as input, see the wiki on how to set them and calib.c on how to read them.

[tom.zhang]

Thank you Nils for your reply.

Sorry I stilll don't get how to convert between the two because I don't understand the code. Could you give me a simple example? Thanks.

[Nils Roos]

See this post.