Pico Max SPI MISO pin

2025-07-09 0:51

Hi,
I'm trying to get SPI communication working on the Pico Max board. In the pinout diagram on the Wiki page I can see that the MISO pin should be GPIO1_C3 (pin 51). I used an oscilloscope to check the data from the slave and it looks okay but the Pico only receives 0x00 indicating that the MISO line is low at all times. Is the Buildroot default SPI0 MISO pin actually pin 51 or how do I check the SPI pin mux? All the other pins (CS, CLK, MOSI) behave as they should.

2025-07-09 1:33

Hello, you can use the "iomux 1 19" command to determine the mapping information of SPI0_MISO_M0. If the returned result is 6, it indicates that it is mapped as SPI_MISO. If the returned result is 0, it means it is in the normal GPIO mode.

2025-07-09 11:13

Crocodile wrote: ↑2025-07-09 1:33 Hello, you can use the "iomux 1 19" command to determine the mapping information of SPI0_MISO_M0. If the returned result is 6, it indicates that it is mapped as SPI_MISO. If the returned result is 0, it means it is in the normal GPIO mode.

It returns 0. How do I find out which pin is actually mapped to SPI_MISO by default? I'm using a breadboard and I'm flexible but I just need to know where to connect the wire to. After "iomux 1 19 6" I receive data on pin 51.