Unable to get the card to work with SD-Card on board #16
Description
Hello,
I have tried all I can think of. I suspect it's a power related problem or a logic level conversion issue.
For example I measured the SD-Card slot voltage at around 3.9v with the two 1n4148's any sd card I try fails 90%+ of the time the other 10% it's very unreliable. I added a 3.3v regulator this helped a little, still fails most of the time.
I have not yet tried different values for the divider resistors 5v to 3.3v conversion. I got side tracked trying a different idea.
I have currently got two SD-Card Arduino mini PCB adaptors connected directly to the atbmega328p. These boards have on board 3.3v regulation and level converters. And They Work!
With these SD-card adaptors I can use the card just fine, once it's been reset CRTL-APPLE-Reset.
The first time you turn the machine on, it still fails and ends up in the Apple monitor. After the press return prompt. At this point if I reset without power off it works fine and keeps working fine until the next power cycle.
I'm happy to use the cards as they work so well. But I was hoping to get, maybe a new version on the sorftware ROM or Atmega with perhaps a delay on power up or an extra reset or something that will stop it failing when powered on?
Has anyone else seen similar issues?
Thanks
Derek