import spidev
import time
import Adafruit_BBIO.GPIO as GPIO

CS_PIN = 'P9_17'
CLK_PIN = 'P9_22'
MOSI_PIN = 'P9_18'
MISO_PIN = 'P9_21'

GPIO.setup(CS_PIN, GPIO.IN)
GPIO.setup(CLK_PIN, GPIO.IN)
GPIO.setup(MOSI_PIN, GPIO.IN)
GPIO.setup(MISO_PIN, GPIO.OUT)

spi = spidev.SpiDev()
spi.open(0, 0)
spi.mode = 0    # Set SPI mode to 0 (CPOL=0, CPHA=0)
spi.max_speed_hz = 500000

def receive_byte():
    byte = 0x0000
    for _ in range(15):
        # Wait for clock signal to go high
        while GPIO.input(CLK_PIN) == GPIO.LOW:
            pass

        # Wait for clock signal to fall low
        while GPIO.input(CLK_PIN) == GPIO.HIGH:
            pass

        # Read MISO_PIN state
        if GPIO.input(MOSI_PIN):
            byte |= 0x0001

        # Shift byte left by 1 bit
        byte <<= 1

    time.sleep(0.0001)
    # Wait for clock signal to fall low before reading the 16th bit
    while GPIO.input(CLK_PIN) == GPIO.HIGH:
        pass

    # Read MISO_PIN state for the 16th bit
    if GPIO.input(MOSI_PIN):
        byte |= 0x0001

    return byte

try:
    while True:
        if GPIO.input(CS_PIN) == GPIO.LOW:
            received_data = []
            while True:  # Continue receiving data until a condition is met
                received_byte = receive_byte()
                received_data.append(received_byte)
                print(f"Received byte: 0x{received_byte:04X}")

except KeyboardInterrupt:
    pass  # Graceful exit on Ctrl+C

spi.close()
GPIO.cleanup()