SPI going crazy in perfboard

  • Noticed that you have both R2 and R3 connected as pullups for IO35.
  • SPI is very sensitive to cable length ... a remedy is most likely using a slower SPI clock.
  • If still issues, could add a 47Ω series resistor to the CLK, MOSI and MISO wires (3 total).
  • Similar problem here [SOLVED]