hi nitish,
i don't think there's an easy way to make all three adc's work at 1 Gsps.
i think one of the adc's works reliably at 1 Gsps.
the other two work reliably around 950 Msps. (i'm not sure about this
number).
if 950 Msps isn't enough for your application,
you could play around with the adc's clock termination resistors and clock
distribution chip parameters,
or use an external dual 1gps zdoc adc.
best wishes,
dan
Dan Werthimer
Marilyn and Watson Alberts Chair
Astronomy Dept and Space Sciences Lab
University of California, Berkeley
On Fri, Oct 11, 2019 at 12:56 AM Nitish Ragoomundun <
nitish.ragoomun...@gmail.com> wrote:
>
> Hi,
>
> I read from the SNAP wiki page that we can operate the SNAP board ADCs at
> 1GSps with 3 channels of input. So, I modified the CASPER SNAP tutorial 3
> to make the ADC work at 1GSps to obtain a 1 channel spectrometer with a
> spectrum of 500 MHz. First I modified the SNAP User IP Clock Rate to 250
> MHz, then changed the snap_adc Sample Rate to 1000 MHz.
>
> Then I modified the script to obtain a 500 MHz spectrum and the ADC
> initialization is done with
>
> adc.init(samplingRate=1000, numChannel=1, resolution=8)
>
> No compilation problem with the toolflow. The script worked the first time
> when I ran it. ADC initialization was fine and I got my 500 MHz spectrum.
> However, when I ran the script a second time, the ADC initialization failed
> with the following messages:
>
> ERROR:root:Frame clock NOT aligned.
> {0: {0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0}, 1: {0: 128, 1: 128,
> 2: 128, 3: 128, 4: 128, 5: 128, 6: 128, 7: 128}, 2: {0: 0, 1: 0, 2: 0, 3:
> 0, 4: 0, 5: 0, 6: 0, 7: 0}}
> ERROR:root:Line clock NOT aligned.
> {0: {0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0}, 1: {0: 39, 1: 39, 2:
> 39, 3: 39, 4: 39, 5: 39, 6: 40, 7: 39}, 2: {0: 0, 1: 0, 2: 0, 3: 0, 4: 0,
> 5: 0, 6: 0, 7: 0}}
> ERROR:root:ADC1 lane0 delay decision failed
> ERROR:root:ADC1 lane1 delay decision failed
> ERROR:root:ADC1 lane2 delay decision failed
> ERROR:root:ADC1 lane3 delay decision failed
> ERROR:root:ADC1 lane4 delay decision failed
> ERROR:root:ADC1 lane5 delay decision failed
> ERROR:root:ADC1 lane6 delay decision failed
> ERROR:root:ADC1 lane7 delay decision failed
> ERROR:root:Line clock NOT aligned.
> {0: {0: 0, 1: 0, 2: 0, 3: 0, 4: 0, 5: 0, 6: 0, 7: 0}, 1: {0: 78, 1: 78, 2:
> 78, 3: 78, 4: 79, 5: 78, 6: 79, 7: 78}, 2: {0: 0, 1: 0, 2: 0, 3: 0, 4: 0,
> 5: 0, 6: 0, 7: 0}}
> ERROR:root:ADC1 lane0 delay decision failed
> ERROR:root:ADC1 lane1 delay decision failed
> ERROR:root:ADC1 lane2 delay decision failed
> ERROR:root:ADC1 lane3 delay decision failed
> ERROR:root:ADC1 lane4 delay decision failed
> ERROR:root:ADC1 lane5 delay decision failed
> ERROR:root:ADC1 lane6 delay decision failed
> ...
>
> I have seen these before with the 800 MSps, but ADC initialization would
> eventually work at the second attempt, whereas 1 GSps, it fails. I have
> increased the number of attempts in calling adc.init( ), but it fails time
> and time again. I also power cycled the board and tried again, but it still
> fails. The strange thing is that it worked the very first time I ran the
> script, but failed every single time after this.
>
> Is there a way to make 1 GSps work reliably over several re-programming
> stages and across reboots.
>
> Regards,
> Nitish
>
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