Beginners • Help with using PICO 2 PIO/FSM to input serial data

Code:

[color=#40BF00]# Program to read data from a depth gauge upon request# 3 Pins required#REQ Output pin from PICO to request data from the gauge#CLK Input pin from the gauge#DATA Input pin to caputure the output data from the gauge## Each data bit from the gauge is "valid" on clock low so sample on CLK lowimport timefrom rp2 import StateMachine, PIO, asm_piofrom machine import Pin  @rp2.asm_pio(out_init=rp2.PIO.OUT_LOW)def mitclkin():     pull()# Pull data for REQ pulse timing        set(isr,0)# zero isr    set(x,31)    label("loop")#generate low going pulse    out(pins, 1)  [31]    jmp(x_dec, "loop")        set(x,27) # Wait for first clock high instance then count 27 clocks which is where the data begins    label("preamble")    wait(1, gpio, 15)    wait(0, gpio, 15)    jmp(x_dec, "preamble")    set(x,7)   # Clock in the next 8 data bits when clock is low    label("bitloop")    wait(1, gpio, 15)    wait(0, gpio, 15)    in_(pins,1)  # shift 1 bit of data from the GPIO pin to the ISR    jmp(x_dec, "bitloop")    push()         # Moves data in the ISR to the rx_fifo Pin(0, Pin.OUT)# REQ Output PinPin(15, Pin.IN)# CLK Input PinPin(14, Pin.IN)# DATA Input Pinsm0 = rp2.StateMachine(0, mitclkin, freq=16000, out_base=Pin(0), in_shiftdir=PIO.SHIFT_RIGHT, in_base=Pin(14))sm0.put(0x7ffffffe)# Value for REQ pulsetime.sleep(0.2)sm0.active(1) # start FSMtime.sleep(1) # Give FSM time to do the shiftingprint("Number of words in rx", sm0.rx_fifo())sm0.active(0)  # stop FSMprint("Number of words in rx", sm0.rx_fifo())[/color]