Thermobot Update

Video of Bot in operation.



The thermobot also stores and plots 24 hours of data. It's finished its job now, but was logging live every minute to a webpage. You can see its results from my conservatory for 16th April 2015 here:

http://jcwyatt.ddns.net/thermobot.html

Initially, pyplot was producing a wierd colouring-in effect under the graph, but adding   

plt.clf()

to reset pyplot after each plot fixed the problem. I discovered this accidentally.

the updated code to include the data logging and plotting is here:

import RPi.GPIO as GPIO
import time
import matplotlib
matplotlib.use('agg')
import os
import matplotlib.pyplot as plt


#pseudo code:
#   fill a list with 60 zeros
# set the t1_temp variable to 18 deg c
# every minute:
# get the t2_temperature from the chip
# ext:write the temperature to a list or database
# calc the temperatures difference from previous value
# move the bot an amount relative to the temp difference

#initialise bot settings (stepper motor))
GPIO.setmode(GPIO.BCM)
 
enable_pin = 18
coil_A_1_pin = 7
coil_A_2_pin = 8
coil_B_1_pin = 23
coil_B_2_pin = 24
 
GPIO.setup(enable_pin, GPIO.OUT)
GPIO.setup(coil_A_1_pin, GPIO.OUT)
GPIO.setup(coil_A_2_pin, GPIO.OUT)
GPIO.setup(coil_B_1_pin, GPIO.OUT)
GPIO.setup(coil_B_2_pin, GPIO.OUT)
 
GPIO.output(enable_pin, 1)
 
delay = 2

def forward(delay, steps):
 for i in range(0, steps):
  setStep(1, 0, 1, 0)
  time.sleep(delay)
  setStep(0, 1, 1, 0)
  time.sleep(delay)
  setStep(0, 1, 0, 1)
  time.sleep(delay)
  setStep(1, 0, 0, 1)
  time.sleep(delay)
 
def backwards(delay, steps):
 for i in range(0, steps):
  setStep(1, 0, 0, 1)
  time.sleep(delay)
  setStep(0, 1, 0, 1)
  time.sleep(delay)
  setStep(0, 1, 1, 0)
  time.sleep(delay)
  setStep(1, 0, 1, 0)
  time.sleep(delay)
 
def setStep(w1, w2, w3, w4):
 GPIO.output(coil_A_1_pin, w1)
 GPIO.output(coil_A_2_pin, w2)
 GPIO.output(coil_B_1_pin, w3)
 GPIO.output(coil_B_2_pin, w4)

#from http://www.modmypi.com/blog/ds18b20-one-wire-digital-temperature-sensor-and-the-raspberry-pi:
#load drivers for temperature probe
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')

temp_sensor = '/sys/bus/w1/devices/28-0414607111ff/w1_slave'

#Get the raw data from the sensor:
def temp_raw():

 f = open(temp_sensor, 'r')
 lines = f.readlines()
 f.close()
 return lines

def read_temp():

 lines = temp_raw()
 while lines[0].strip()[-3:] != 'YES':
  time.sleep(0.2)
  lines = temp_raw()
        
 temp_output = lines[1].find('t=')

 if temp_output != -1:
  temp_string = lines[1].strip()[temp_output+2:]
  temp_c = float(temp_string) / 1000.0
  return temp_c

#initialise current temperature
currentTemp = 14.00

#make an empty list for 24 hours worth of data
tempLog = [0] * (60*24)

#run the bot
while True:
  oldTemp = currentTemp
  currentTemp = read_temp()
  tempDiff = currentTemp - oldTemp
  if tempDiff >= 0:
   steps = tempDiff * 256
   forward(int(delay) / 1000.0, int(steps)) 
  else:
   steps = tempDiff * -256
   backwards(int(delay) / 1000.0, int(steps))
  setStep(0,0,0,0)

#now do the graph stuff:
#add the new reading to the end of the list 

  tempLog.append(currentTemp)

#delete the first item in the list

  del tempLog[0]

#plot the graph as an image    
  
  plt.plot(tempLog)
  plt.ylabel ('Bedroom Temperature (deg C)')
  plt.xlabel ('Time (minutes) (Full width = 24hrs)')
  plt.savefig('/var/www/images/tempLog.png')
  plt.clf()

  hrlog=(tempLog[-60:]) 
  plt.plot(hrlog)
  plt.ylabel ('Temp (deg C)')
  plt.xlabel ('Time (minutes) last hour')
  plt.savefig('/var/www/images/tempLog60.png')
  plt.clf()

  time.sleep(60)