Incredible!!! Thanks, Pavel!
dol@ с iPad > 22 мая 2016 г., в 14:37, Pavel Shatov <[email protected]> написал(а): > > Hello! > > I got one of the Alpha boards from Fredrik and was busy trying to bring up > the two on-board SDRAM chips. I believe, I finally have them working. > > There turns out to be a stupid bug in low-level HAL code. Actually, there are > in fact two similar bugs, that don't cancel each other out unfortunately. > > In brief, our STM32 should have two independent SDRAM banks. When you start > reading the fine print, you find out that they are not completely > independent, i.e. they can only operate at the same frequency and share some > of the timing parameters. This is not a problem itself, because we have two > identical memory chips. The problem is that there are two configuration > registers, the first register also controls some of the parameters for the > second bank, therefore in the second register corresponding control bits are > reserved. Sane person would configure the first bank, read its configuration > register, mask reserved bits and write into the second bank. I believe this > is what original FMC_SDRAM_Init() and FMC_SDRAM_Timing_Init() thought they > were doing when they tried to configure the second bank, but those functions > just messed up configuration of both banks instead. > > Anyways, both external memory chips seem to work now. I uploaded simple test > program, that basically fills entire memory with pseudo-random pattern, reads > it back and compares with what was written. > > > -- > With best regards, > Pavel Shatov > _______________________________________________ > Tech mailing list > [email protected] > https://lists.cryptech.is/listinfo/tech _______________________________________________ Tech mailing list [email protected] https://lists.cryptech.is/listinfo/tech
