Andreas-Ley
commented
2 years ago I added 2k pullups to all data lines. For DAT1 and DAT2 I added two initially open solder bridges so we can still decide to pull them up or down.
Closed moffel closed 2 years ago
Andreas-Ley
commented
2 years ago I added 2k pullups to all data lines. For DAT1 and DAT2 I added two initially open solder bridges so we can still decide to pull them up or down.
The SD-Card interface requires pull-up's on DAT0, DAT1 and DAT2 in SPI mode. The pull-up on DAT0 is missing.
During tests the SD-Card did not respond at all. When enabling the FPGA weak-pull-up the SD-Card works as expected. However the weak-pull-up has a resistance of up to 45kOhm and varies a lot. This may hinder fast SPI clock speeds and is subject to silicon lottery. We should therefore add another pull-up to DAT0.