Raspbery Pi Analog Input with ADC0832

RPi_ADC8032.py

#!/usr/bin/env python
#
# Analog Input with ADC0832 chip
#
# Datasheet: http://www.ti.com/lit/ds/symlink/adc0838-n.pdf
# Part of SunFounder LCD StarterKit
# http://www.sunfounder.com/index.php?c=show&id=21&model=LCD%20Starter%20Kit
#

import time
import os
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)

# change these as desired - they're the pins connected from the
# SPI port on the ADC to the Cobbler
PIN_CLK = 18
PIN_DO  = 27
PIN_DI  = 22
PIN_CS  = 17

# set up the SPI interface pins
GPIO.setup(PIN_DI,  GPIO.OUT)
GPIO.setup(PIN_DO,  GPIO.IN)
GPIO.setup(PIN_CLK, GPIO.OUT)
GPIO.setup(PIN_CS,  GPIO.OUT)

# read SPI data from ADC8032
def getADC(channel):
	# 1. CS LOW.
        GPIO.output(PIN_CS, True)      # clear last transmission
        GPIO.output(PIN_CS, False)     # bring CS low

	# 2. Start clock
        GPIO.output(PIN_CLK, False)  # start clock low

	# 3. Input MUX address
        for i in [1,1,channel]: # start bit + mux assignment
                 if (i == 1):
                         GPIO.output(PIN_DI, True)
                 else:
                         GPIO.output(PIN_DI, False)

                 GPIO.output(PIN_CLK, True)
                 GPIO.output(PIN_CLK, False)

        # 4. read 8 ADC bits
        ad = 0
        for i in range(8):
                GPIO.output(PIN_CLK, True)
                GPIO.output(PIN_CLK, False)
                ad <<= 1 # shift bit
                if (GPIO.input(PIN_DO)):
                        ad |= 0x1 # set first bit

        # 5. reset
        GPIO.output(PIN_CS, True)

        return ad

if __name__ == "__main__":
        while True:
                print "ADC[0]: {}\t ADC[1]: {}".format(getADC(0), getADC(1))
                time.sleep(1)

Thanks for this code @HeinrichHartmann. I've had this successfully running a month ago, but it is no longer working for me. I'm wondering if it is my ADC chip that has burnt out. Could you do me a favour and tell me if connecting the Vcc to the 3v source, and GND to RPi's ground creates a circuit? For me, I'm getting 0 voltage through GND, which is leading me to believe my chip has broken (I have two, and both do the same thing though).

Dear @pelson here is a full description of my setup http://heinrichhartmann.com/2014/12/14/Sensor-Monitoring-with-RaspberryPi-and-Circonus.html

In looking at the ADC0832 datasheet I see there is a second set of 8 bits after the first set, why do you not read these?
The datasheet shows it taking about 20 clock cycles total to setup/read, are you using the CS line to 'reset' and not clock out the last 8 bits?
If so, why are you ignoring the last 8 bits??
Thanks!