Hi Franco, Sorry, I missed your note in your first email where you already said you used the ruby init code with demux 1. This is correct for the 16-input configuration you are using. In this configuration, the FPGA and ADC should both run at the same clock rate. If you put in a 140MHz clock and est_brd_clk() returns ~140 that is a good sign. I assume you're using the latest roach2 branch on github.com/casper-astro/mlib_devel? Does the ruby initialization script suggest anything is wrong in the initialization? In the same repository as the adc16_init script, there is also a script to plot adc outputs -- adc16_plot_chans.rb . Does this give the same sample duplication you see in your snapshots? I assume that the User IP Clock source in your design is correctly set to adc0? (not user_clk/sys_clk?)
Thats all I can think to check right now... Good luck! Jack On Wed, 3 Apr 2019 at 16:57, Franco <[email protected]> wrote: > Hi David and Jack, > > Interesting. Yes I'm using a 140MHz clock (I'm injecting a 140MHz tone > into the adc clock input). I'm sure the FPGA is running at 140MHz because I > checked it with fpga.est_brd_clk(). Also, the data duplication occurs for > all 16 inputs, so my guess is that is a problem at the adc board level. I'm > using the adc_init.rb code with the '--demux 1' flag (I understand that > this is the 16 in mode), however I copied this code from someone else, so > maybe is an old version. I'll try to use the latest version to see if that > is the problem. I'll also try a different (valid) sampling frequency. > > Thanks for the suggestions, > > Franco > > On Wed, Apr 3, 2019 at 9:07 AM Jack Hickish <[email protected]> wrote: > >> Hi Franco, >> >> In addition to Dave's advice-- how are you configuring your board? After >> programming the FPGA, you'll need to appropriately configure the ADC to >> operate in the right mode. The code seems to be linked here -- >> https://casper.ssl.berkeley.edu/wiki/ADC16x250-8_coax_rev_2 >> >> Cheers >> Jack >> >> On Wed, 3 Apr 2019 at 00:53, Franco <[email protected]> wrote: >> >>> Hi Casperites, >>> >>> I'm working in some project that uses a ROACH2 and an adc16x250-8 ADC >>> board. When I check the raw data from the ADC using a snapshot block I see >>> this weird effect where two consecutive samples have always the same value, >>> as shown in this image: >>> >>> https://my.pcloud.com/publink/show?code=XZMRx67Zpj7XjnkE5PypVuuDCB9Mhu8IJJ37 >>> >>> According to an ex-coworker, this is the expected behavior of the >>> adc16x250-8 board in 16 input mode, because of some constraints in the >>> communication between the ADC and the FPGA, the FPGA must run at twice the >>> speed to correctly receive the sampled data. However, couldn't find any >>> explicit mention of this phenomenon in the CASPER website or mailing list. >>> Can someone confirm this is the correct behavior so I can get peace of mind >>> :)? >>> >>> Some info of my test: >>> - Board: ROACH2-rev2 >>> - ADC: ADC16x250-8 coax rev2 >>> - ADC mode: 16 inputs (demux 1, using David Macmahon initalization code) >>> - User IP Clock Rate: 140 MHz >>> - Actual clock frequency used in the adc board: 140MHz >>> >>> Thanks, >>> >>> Franco Curotto >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "[email protected]" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "[email protected]" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> > -- > You received this message because you are subscribed to the Google Groups " > [email protected]" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > -- You received this message because you are subscribed to the Google Groups "[email protected]" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected].
