from machine import Pin
from rp2 import PIO, StateMachine, asm_pio
import time

# Set up GPIO 0 as an output pin to generate a square wave
output_pin = Pin(0, mode=Pin.OUT,pull=Pin.PULL_UP)

# Set up GPIO 1 as an input pin to read the square wave
input_pin = Pin(1,mode=Pin.IN, pull=Pin.PULL_UP)

# Define a PIO program that reads from the input pin and shifts right
@asm_pio(in_shiftdir=PIO.SHIFT_RIGHT,autopush=True, 
         push_thresh=8)
def pio_program():
     wrap_target()
     in_(pins, 1)  # Read 1 bit from the GPIO pin into the ISR
     wrap()# Push the ISR content to the RX FIFO

# Initialize the state machine
sm = StateMachine(0, pio_program, freq=20000, in_base=input_pin)

# Start the state machine
sm.active(1)
print("State machine started")

# Function to generate a square wave on the output pin
def generate_square_wave(pin, frequency=1.0):
    period = 1 / frequency
    half_period = period / 2
    while True:
        pin.value(0)  # Set pin high
        time.sleep(half_period)
        pin.value(1)  # Set pin low
        time.sleep(half_period)

# Main loop: Generate the square wave and read from the PIO RX FIFO
square_wave_frequency = 5000000 # Frequency of the square wave in Hz
half_period = 1 / (2 * square_wave_frequency)  # Calculate half period for timing

while True:
    # Generate square wave
    output_pin.value(1)  # Set pin high
    time.sleep(half_period)
    output_pin.value(1)  # Set pin low
    time.sleep(half_period)
    
    # Check and read data from the RX FIFO
    if sm.rx_fifo():  # Check if there's data in the RX FIFO
        value = sm.get()  # Get the value from the RX FIFO
        print("Content of RX FIFO:", bin(value))
    else:
        print("No data in RX FIFO")
    #time.sleep(0.5)  # Add a small delay to make the output more readable