- Announcement about May 10th, 2018 update and your password.
SD is booting fine on the P2.
However, in order for the SD routines to work not only at the RC speed which is ~30MHz max, but to also work with user code that may be running up to ~200MHz max for us overclockers if we can get away with it. To satisfy this, the timeout of 1s needs to be calculated for the fastest speed (200MHz). This gives around 10s timeout at 20MHz (the current testing FPGA RC speed). Under normal circumstances, this is an SD card issue, and nothing we do will speed up the card.
But the problem lies if there is a pull-up on P60 (the CSn pin of the SD card) but no card. Chip revealed this during testing of the pullups recently. We decided to pass at that point. The SD card is providing the internal pullup - we are recommending using the SD's internal pull-up for circuitry, so why would there be a pullup present without an SD card. Well, it's possible the SD card has failed. How possible? I don't know.
So, if an SD card is present, but it is failing to respond to the initialisation sequence, the 1s timeout at the fastest speed will give around 7s at the RC Boot speed of the P2. This means that before the serial can take over upon an SD boot failure, around 7s may have elapsed. Note that this is a faulty SD hardware problem. Easy solution is to remove or replace the SD card and the problem is solved. Note if the boot sectors or boot files are not found, the SD boot code will return as fast as the SD responds which is usually ~25-100ms.
While the final ROM window remains open, I would like to try a few solutions. BUT, I need as many of you as possible to test as many SD cards as you can, just to ensure I don't break something.
So, what is your best hardware to do this?
a) P2 - Again I can give you the source to recompile. But what FPGA boards and FPGA code? I am presuming the full P2 version 32a/b. A couple of the early v32 and prior have the SD cards mapped to P58-62 and these should work fine for this testing. The test rom code we are testing with is only available for 123 A9 and BeMicroCV-A9 boards.
b) P1 - I can give you source to recompile to any pins and xtal
I am not even certain I will have the time to do this, but perhaps its worth a try.