import time
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)

# read SPI data from MCP3204 chip, 4 possible adc's (0 thru 3)
def readadc(adcnum, clockpin, mosipin, misopin, cspin):
    if adcnum > 3 or adcnum < 0:
        return -1
    GPIO.output(cspin, GPIO.HIGH)
    GPIO.output(clockpin, GPIO.LOW)
    GPIO.output(cspin, GPIO.LOW)

    commandout = adcnum
    commandout |= 0x18  # start bit + single-ended bit
    commandout <<= 3    # we only need to send 5 bits here
    for i in range(5):
        if commandout & 0x80:
            GPIO.output(mosipin, GPIO.HIGH)
        else:
            GPIO.output(mosipin, GPIO.LOW)
        commandout <<= 1
        GPIO.output(clockpin, GPIO.HIGH)
        GPIO.output(clockpin, GPIO.LOW)
    adcout = 0
    # read in one empty bit, one null bit and 10 ADC bits
    for i in range(13):
        GPIO.output(clockpin, GPIO.HIGH)
        GPIO.output(clockpin, GPIO.LOW)
        adcout <<= 1
        if 0 < i and GPIO.input(misopin) == GPIO.HIGH:
            adcout |= 0x1
    GPIO.output(cspin, GPIO.HIGH)
    return adcout

# ADC CH number (0-3)
ADCCH = 0

# SPI port on the ADC to the Cobbler
SPICLK = 18
SPIMISO = 23
SPIMOSI = 24
SPICS = 25

# set up the SPI interface pins
GPIO.setup(SPIMOSI, GPIO.OUT)
GPIO.setup(SPIMISO, GPIO.IN)
GPIO.setup(SPICLK, GPIO.OUT)
GPIO.setup(SPICS, GPIO.OUT)

# to indicate ADC data
try:
    while True:
        inputVal0 = readadc(ADCCH, SPICLK, SPIMOSI, SPIMISO, SPICS)
        print(inputVal0)
        time.sleep(0.5)

except KeyboardInterrupt:
    print("Cleanup")
    GPIO.cleanup()