Thanks Jack and Rurik, When I calibrated mmcm phase, it didn't find the optimal mmcm phase. Why is that? and any ideas of how to correct it or what I should look at to fix the problem? Thanks!
Weiwei On Thu, Jan 30, 2014 at 4:04 PM, Jack Hickish <[email protected]> wrote: > On 30 January 2014 23:56, Primiani, Rurik <[email protected]> > wrote: > > Hi Weiwei, > > > > Have you calibrated the MMCM phase using test vectors? The following > > repository hosts Python/corr code that may be helpful to you: > > > > https://github.com/sma-wideband/adc_tests > > > > I've recently updated the README, please see the "Calibrating the > > data-to-clk" for instructions on how to use the code. I believe this may > > correct the bit errors you're seeing. Note: this code assumes that your > > bitcode has a snapshot hooked up to your raw ADC output _after_ it's been > > converted to signed two's. > > > > Alternatively there is some code out there (I believe written by Jack > > Hickish) that adjusts the IODELAYs on each data bit to correct for > capture > > errors. > > > > Just to say, this code is in a fork of the sma repo, at > https://github.com/jack-h/adc_tests > But you won't need to calibrate per-bit unless you're running the adc > near full speed, and even then, you could probably get by without. > > > Lastly, please keep in mind that this ADC has four interleaved cores each > > with their own phase, bias, and gain differences. These may need to be > > adjusted as well depending on your application. > > > > Best, > > > > Rurik > > > > On Jan 30, 2014 6:36 PM, "Weiwei Sun" <[email protected]> wrote: > >> > >> Hi Rurik and Casparians, > >> > >> I have a problem with the data out of the adc5g yellow block and 2's > >> complementary change and captured by a snapshot. It seems there is bit > >> errors during the transmission, or it could be some other problem. This > is > >> roach2 with an adc5g clocked at 1400MHz, 2-channel, Nondemux (1:1) mode. > >> > >> I tested it with a 175MHz sinusoid wave generated by a signal generator. > >> The samples are predicted to be constant for every stream of the total 8 > >> output streams with amplitude 32 within range (-128, 127), but I saw a > lot > >> of bit errors (bit flip? ). Attached are the time series of the 8 > streams. > >> Has anyone experienced this weird data? I'm appreciated of your > attention > >> and advice! Thanks! > >> > >> Weiwei > >> > > >
