#!/usr/bin/python
#
# thingspeak.py
#
# May.17/2015: v1.00 released
#
# Logging from Raspberry Pi data acquisition source to ThingSpeak.com IoT service
#
# http://www.mikronauts.com/raspberry-pi/raspberry-pi-iot-experiments-and-howto/
#
# Copyright 2015 William Henning
# http://Mikronauts.com
#
# Related Links:
#
# https://github.com/jerbly/Pi/blob/master/raspi-adc-pot.py
# http://www.raspberrypi.org/forums/viewtopic.php?t=37550&p=320440
# from http://git.agocontrol.com/apagg/agocontrol-work/blob/93f7d9051aebf79c794e3d5fa4feea92c9221831/raspiMCP3xxxGPIO/MCP3208.py

import RPi.GPIO as GPIO
import spidev
import urllib as web
import time
import os

# module constants - SPI multiplexer address lines

A2 = 25
A1 = 24
A0 = 23

# optimize python SPI requests
req=[[6,0,0], [6,64,0],[6,128,0],[6,192,0],[7,0,0], [7,64,0],[7,128,0],[7,192,0]]

# read SPI data from MCP3208 chip, 8 possible adc's (0 thru 7)
def readadc(adcnum):
    r = spi.xfer2(req[adcnum])
    return ((r[1]&15)<<8) + r[2]

# select SPI device
def spi_device(devno):
    GPIO.output(A2,(devno >> 2)&1)
    GPIO.output(A1,(devno >> 1)&1)
    GPIO.output(A0,devno & 1)

# scan 8 channels on selected MCP3208
def scan_adc(n):
    print "--------------------------"
    print "SPI DEVICE", n, "SCAN ", count
    spi_device(n)
    if (n==6):
        mul=0.001
    else:
        mul=0.002
    url = "https://api.thingspeak.com/update?key=XXXXXXXXXXXXXXXXXX&headers=false"
    for chan in range(0,8):
        x = readadc(chan)
        url = url + "&field"+str(chan+1)+"="+str(x*mul)
        print chan, x*mul
    try:
        resp = web.urlopen(url).read()
    except:
        print "Web error"
        csv = csv + ", -1"
    csv = csv + "\n"

# main program

# initialize multiplexer, I/O's, and stream data to ThingSpeak IoT service.

GPIO.setmode(GPIO.BCM)
GPIO.setup(A2, GPIO.OUT)
GPIO.setup(A1, GPIO.OUT)
GPIO.setup(A0, GPIO.OUT)

spi = spidev.SpiDev()
spi.open(0,1)   # open(port,CS) port=0, CS=0|1
spi.max_speed_hz=1953000  # default speed undervalued divided voltages

count = 0
errs = 0

while 1:
    scan_adc(1)
    time.sleep(60)
    count = count + 1