Are there any spare GPIOs available on the VGA demo base if the sound and SD card are also in use?
There’s a group of six pads labelled “GP21”, “GP20”, “SDD2”, “SDD1” and “SD JUMPERS”, but no documentation that I can find that says what they’re for. The actual GP20 and GP21 pins appear to be connected to the SD card for QSPI mode.
I’d really like to run an SPI interface into this board to use it is a co-processor for another project.
My best guess would be they are for the SD card slot.
GP21 looks to go to SDD2 and
GP20 looks to go to SDD1
Cut the track between them to reuse GP21 and GP22 for something else?
It seems this board is an implementation of a RPi reference circuit, and in fact those two pins are not connected to the SD card by default unless jumpered.
However that’s still one pin short (assuming no /SS line in use) of the three needed for a bidirectional SPI interface, and the pins used aren’t ones mappable to the internal SPI device (but potentially usable as SPI via PIO?)
They look to have a jumper / track already there linking the solder pads? I can see what looks like a cooper line that you would cut to isolate them.
Yes, you’re right - I just buzzed them through with my multimeter. I guess the board isn’t exactly per the reference design. The bottom pair of pins are connected to GND.
I only just got my Pico today, and don’t have that add on. Hopefully the documentation improves with more details,