HyperRAM test ok on new FPGA board CR00107

 This board CR00107 arrived yesterday from the production downstairs:

Getting LED blinking was simple but does the HyperRAM also work? Testing out the OpenHBMC IP core. Creating the project and changing constraints. And trying out. And it works, memory tests are passing on the AXI HyperRAM. Cool.

Not so cool, there are random errors when running the memory test in the loop. It seems the issue is related to the relation of axi clock to hyperbus clock. If they are the same 100MHz this causes most failures. Using axi clock of 81.81818MHz and we have way fewer failures.

Changing the hyperBus IP core clocking from BUFG to BUFIO/BUFR mode. And this fixed the issue, no more failures, and also with 100MHz axi clock!

Cool, it REALLY works!

Was happy to fast, after one week of continuous testing, the memory test failed. Pretty hard case to troubleshoot a problem that may come once a week. Next tests seem to fail about once a day, but last test has run over two weeks without failing. Complicated.