adafruit-cosm-temp.py

#!/usr/bin/env python
import time
import os
import RPi.GPIO as GPIO
import eeml
from eeml import CosmError

GPIO.setmode(GPIO.BCM)
DEBUG = 1
LOGGER = 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 /= 2       # 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)

# COSM variables. The API_KEY and FEED are specific to your COSM account and must be changed 
#API_KEY = '5RNOO3ShYJxYiq2V2sgSRtz3112SAKxFQjNDQmNXc0RScz0g'
#FEED = 68872
API_KEY = 'YOUR_API_KEY'
FEED = YOUR_FEED_ID

API_URL = '/v2/feeds/{feednum}.xml' .format(feednum = FEED)

# temperature sensor connected channel 0 of mcp3008
adcnum = 0

while True:
        # read the analog pin (temperature sensor LM35)
        read_adc0 = readadc(adcnum, SPICLK, SPIMOSI, SPIMISO, SPICS)

        # convert analog reading to millivolts = ADC * ( 3300 / 1024 )
        millivolts = read_adc0 * ( 3300.0 / 1024.0)

        # 10 mv per degree 
        temp_C = ((millivolts - 100.0) / 10.0) - 40.0

        # remove decimal point from millivolts
        millivolts = "%d" % millivolts

        # show only one decimal place for temprature and voltage readings
        temp_C = "%.1f" % temp_C

        if DEBUG:
                print "read_adc0:\t", read_adc0
                print "millivolts:\t", millivolts
                print "temp_C:\t\t", temp_C
                print

        if LOGGER:
                # open up your cosm feed
                pac = eeml.Pachube(API_URL, API_KEY)

                #send celsius data
                pac.update([eeml.Data(0, temp_C, unit=eeml.Celsius())])

                # send data to cosm
                try:
                    pac.put()
                except CosmError, e:
                    print('ERROR: pac.put(): {}'.format(e))
                except StandardError:
                    print('ERROR: StandardError')
                except:
                     print('ERROR: Unexpected error: %s' % sys.exc_info()[0])

        # hang out and do nothing for 10 seconds, avoid flooding cosm
        time.sleep(30)