Created
August 2, 2012 18:13
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pi demo
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#!/usr/bin/env python | |
import time | |
import os | |
import RPi.GPIO as GPIO | |
GPIO.setmode(GPIO.BCM) | |
DEBUG = 1 | |
# read SPI data from MCP3008 chip, 8 possible adc's (0 thru 7) | |
def readadc(adcnum, clockpin, mosipin, misopin, cspin): | |
if ((adcnum > 7) or (adcnum < 0)): | |
return -1 | |
GPIO.output(cspin, True) | |
GPIO.output(clockpin, False) # start clock low | |
GPIO.output(cspin, False) # bring CS 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, True) | |
else: | |
GPIO.output(mosipin, False) | |
commandout <<= 1 | |
GPIO.output(clockpin, True) | |
GPIO.output(clockpin, False) | |
adcout = 0 | |
# read in one empty bit, one null bit and 10 ADC bits | |
for i in range(12): | |
GPIO.output(clockpin, True) | |
GPIO.output(clockpin, False) | |
adcout <<= 1 | |
if (GPIO.input(misopin)): | |
adcout |= 0x1 | |
GPIO.output(cspin, True) | |
adcout >>= 1 # first bit is 'null' so drop it | |
return adcout |
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