I am having problems getting all 4 ADC cores on the FMCADC4 synchronized.
For all of my tests, I fed a common signal to both AD9680 chips, and looked at the data using Chipscope.
Case 1: No changes to the GitHub code.
Result: 2 times out of 6 all 4 waveforms were aligned. Otherwise, the outputs of the the 2 ADCs were off by as much as 5 samples.
Case 2: Made the following changes to the ad9680.c
ad9680_spi_write(slave_select, 0x120, 0x1C); // NSHOT sysref
ad9680_spi_write(slave_select, 0x121, 0x002); // ignore first 2
Result: 4 times out of 8 all 4 waveforms were aligned.
Case 3: Made the following changes:
jesd204b_st.sysref_always_enable = 1;
Added the following in ad9680.c
ad9680_spi_write(slave_select, 0x120, 0x1A); // Continous sysref
Result: Unrecognizable waveforms.
Could someone please tell me what I need to do in order to reliably synchronize all 4 waveforms?