Added script to read temperature with TMP36 and MCP3008 analog to dig…

…atal convert

tmp36_analog.py

@@ -0,0 +1,78 @@
+#!/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
+
+# change these as desired - they're the pins connected from the
+# 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)
+
+# TMP36 connected to adc #0
+temp_adc = 0;
+
+try:
+	while True:
+		value = readadc(temp_adc, SPICLK, SPIMOSI, SPIMISO, SPICS)
+		mVolts = value * (3300.0 / 1024.0) 
+		temp = ((mVolts - 100.0) / 10.0) - 40.0
+
+		if DEBUG:
+			print "Value: ", value
+			print "MilliVolts: ", "%d" % mVolts
+
+		print "Temperature: ", "%.1f" % temp
+		print "\n"	
+
+		# hang out and do nothing for a half second
+		time.sleep(1)
+
+except KeyboardInterrupt:
+        GPIO.cleanup()