Raspberry Pi GPIO to Xively python example?

Question

I am a non-programmer feeling my way through Xively with a Raspberry Pi running python. I have successfully worked through the tutorial given on the xively site given here: https://xively.com/dev/tutorials/pi/

The next step in my project is to continuously take readings from one of the GPIO pins (simply whether it's high or low) do some calculations and once a minute supply a number to an Xively feed.

I have the GPIO portion working right in a separate program. But I'm running into problems when I try to incorporate this into the Xively tutorial example program I got running.

I am now thinking that I should have the GPIO program and the Xively programs running simultaneously with the GPIO program writing data to a file and the Xively program reading from that file and uploading the data to the feed. So my question is: Is this possible and reasonably easy to execute?

Alternatively, if someone could point me to an example where the Xively tutorial example was modified to accept GPIO inputs, that would also help.

And if there is a better/simpler way to accomplish what I'm after, I'm open to suggestions...

Answer 1

You need to :

Download and Install Xively Python Library first. Download and Install httplib2 module.

You can combine your "GPIO Sensor" script and your "Send Data to Xively" script.

Here's a sample code for you (it's for Raspberry Pi and DHT 11) :

#!/usr/bin/python

# Import required Python libraries
import RPi.GPIO as GPIO
import time
import random
import datetime
import json
import sys
import Adafruit_DHT
# Custom HTTP Library
import httplib2

# Use BCM GPIO references
# instead of physical pin numbers
#GPIO.setmode(GPIO.BCM)

# Define GPIO to use on Pi

# Set pin as input
#GPIO.setup(GPIO_PIR,GPIO.IN)

# Define sensor state (1 by default)
SENSOR_STATE = 1

DHT_TYPE = Adafruit_DHT.DHT11
DHT_PIN  = 22
# Define URLs and API key for sending and receiving requests
sensorURL = ""
temperatureURL = ""
humidityURL = ""
API_KEY = ""

# Retrieve latest sensor state from Xively via GET request
def retrieve_sensor_state():
  try:

    global SENSOR_STATE  
    print "\nRetrieving from Xively"

    h = httplib2.Http(disable_ssl_certificate_validation=True)
    (resp_headers, content) = h.request(sensorURL, "GET", headers={'X-ApiKey':API_KEY})
    jsonData = json.loads(content)
    SENSOR_STATE = jsonData["current_value"]
    print "Sensor state: " + SENSOR_STATE
    if (SENSOR_STATE == str(1)):
       upload_to_xively()
       print "continuing!"
    else:
       print "sensor is disabled!"  

  except:
    print "Error occurred!"

# Upload sensor data to Xively via PUT request
def upload_to_xively():
  try:

    print "Uploading to Xively"

    now = str(datetime.datetime.now())
    humidity, value = Adafruit_DHT.read(DHT_TYPE, DHT_PIN)
    if humidity is not None and value is not None:
        print "temperature value :" + str(value) + "    |    " + str(now)
        print "humidity value :" + str(humidity) + "    |    " + str(now)

        jsonString = {"id":"temperature","tags":[],"unit":{},"current_value":value}
        publishString = json.dumps(jsonString)

        h = httplib2.Http(disable_ssl_certificate_validation=True)
        (resp, content) = h.request(temperatureURL, "PUT", body=publishString, headers={'X-ApiKey':API_KEY})

        jsonString1 = {"id":"humidity","tags":[],"unit":{},"current_value":humidity}
        publishString1 = json.dumps(jsonString1)
        g = httplib2.Http(disable_ssl_certificate_validation=True)
        (resp, content) = g.request(humidityURL, "PUT", body=publishString1, headers={'X-    ApiKey':API_KEY})
    else:
    print "failed to read data! Trying again"

  except:
    print "Error occurred!"

# Callback function from event handler when motion is detected
#def motion_callback(GPIO_PIR):

#  global SENSOR_STATE
  # Log the sensor data down only if sensor state = 1 (enabled)
#  if SENSOR_STATE == str(1):
#    if GPIO.input(GPIO_PIR):
#        print "\nMotion Detected! @ " + datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
#        upload_to_xively()
#        time.sleep(1)
#    else:
#        print "\nBack to Normal"

# Main program
print "DHT Module Test (Ctrl+C to exit)"
time.sleep(2)
print "Ready"

try:
  while True: 
    retrieve_sensor_state()
    time.sleep(10)
    continue

except KeyboardInterrupt:
  print "Quit"
  GPIO.cleanup()