I connected my logic analyzer (Analog Discovery 2) to the 74HC595 shift register. It appears that the SER, SRCLK, and RCLK lines are toggling, but the outputs all remain at logic high. I would expect these lines to toggle to control the serial data going to the NeoPixels.
To make sure that my 74HC595 is working, I ran the demo code found on this tutorial: https://learn.adafruit.com/74hc595/overview. The only change I made was to support the Pico pin names:
Code: Select all
latch_pin = digitalio.DigitalInOut(board.GP1)
spi = busio.SPI(board.GP2, MOSI=board.GP3)
sr = adafruit_74hc595.ShiftRegister74HC595(spi, latch_pin)
This seemed to at least confirm my shift register is working:
Any help to debug the NeoPIO circuit/code would be appreciated!