import datetime
import RPi.GPIO as GPIO

GPIO.setwarnings(False)
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

def mcp3204_data():

    wcd = []

    # ADC CH number (0-3)
    ch = 0
    CH_MAX = 1
    
    # sensor value
    MAX_VALUE = 3520
    MIN_VALUE = 2420

    # 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
#    print(datetime.datetime.now())

    while ch <= CH_MAX:
        inputVal0 = readadc(ch, SPICLK, SPIMOSI, SPIMISO, SPICS)
        dt = 100 - (inputVal0 - MIN_VALUE) / ((MAX_VALUE - MIN_VALUE) / 100)
        wcd.append('{:3.1f}'.format(dt))
#        print(wcd[ch])
        print('Channel-{0} Water Content: {1} %'.format(ch, wcd[ch]))
        ch += 1

    return wcd


if __name__ == '__main__':
    mcp3204_data()