I have an SD breakout for my Due that isn't properly detecting the SD card. On one card, it cannot detect at all, and the other it says that the SD isn't formatted with FAT, even though it is. Here is my wiring:
simulate this circuit – Schematic created using CircuitLab
So, I broke out my oscilloscope and started probing lines. One in specific I got worried about, is the SCK line and it's bouncing, specifically from the inductance of the jumpers. This is the SCK line from my scope:
My reaction was to put some buffer caps on there, and so I put 2x 300pf capacitors in parallel for a total of 600pf. This is the waveform as measured after I put in the debouncing caps:
This is much more tolerable, and I can accept this level of bouncing for the SCK line, as I doubt that there will be much misfiring. I upload the
SD card test sketch that's on the website, here is the output:
Initializing SD card...Wiring is correct and a card is present. Card type: SD2 Could not find FAT16/FAT32 partition. Make sure you've formatted the card
What does The Arduino Due have that makes it hard to detect the card?