I dug a bit deeper and whilst doing cmake I pass it the board type:
cmake -D"PICO_BOARD=vgaboard" …
(not sure why that shows as 3 dots - should be 2)
which led me to find this file:
/opt/pico-sdk/src/boards/include/boards/vgaboard.h
that defined these values:
// Note DAT1/2 are shared with UART TX/RX (pull jumpers off header to access
// UART pins and disconnect SD DAT1/2)
#define VGABOARD_SD_CLK_PIN 5
#define VGABOARD_SD_CMD_PIN 18
#define VGABOARD_SD_DAT0_PIN 19
and I was using SD_CS PIN 22 in my C code and spi1.
Using these values I still cannot get it to initialise from C/C++,
SD card mount file system failed ,error code :(3)
so maybe you are right… it might not be SPI?
In which case, are there any c/c++ examples out there that access the sd-card on the pico demo board? I cannot seem to find anything.
I did find an example of someone using the pico dvi board (hdmi version) and their code doesn’t seem to do anything smart with the sdcard, so I’m a bit baffled - did I just get a broken board and I’ve been chasing my tail all along?