Introduction

Hi,

My name is Tim and I've just purchased a Beaglebone Black (BBB) revision C1 which runs Debian Linux.  This little computer will make a nice little controller for a few projects I have in mind. I choose the BBB for it's size, it fits in an Altoids tin, though I'll be using at least two capes so the projects will not be housed in a tin.

I spent an evening learning and experimenting with a breadboard, some jumper wires and some simple components such as LEDs, switches, resistors, and a thermistor.

I managed to program the BBB to flash a LED, turn on the LED with a switch, read the voltage from the thermistor and then combined two programs to monitor the thermistor and turn on the LED when the voltage rose above a certain level and off again when it dropped below. This code will be the start of my Brew Chamber Controller.

Here is the thermistor.py code:
#############################################################################
#!/usr/bin/python
import Adafruit_BBIO.ADC as ADC
import Adafruit_BBIO.GPIO as GPIO
import time
import math

ADC.setup()
GPIO.setup("P8_12", GPIO.OUT)

#setup the values used for calculations dependent on the thermistor we are using
r_bias = 10000 #voltage divider resistance used 10k ohms
r_alpha = .09919
Bvalue = 3650 #from the thermistor data sheet (B value)

c2kelvin = 273.15 #this is a constant

print "\n\nPress CTRL-C to exit program.\n\n"

while True: #loop through this code forever or until CTRL-C is pressed

  adcValue = ADC.read("P9_36") #read the thermistor voltage divider reading

  #do some calculations
  r_therm  = ((1/adcValue)-1)*r_bias
  t_c      = 10*((Bvalue/math.log((r_therm/r_alpha)))-c2kelvin)/10 #calculate Celsius
  t_f      = (t_c * 9/5) +32 #calculate Fahrenheit

  print "ADC:", adcValue," | Resistance:", r_therm," | Celsius:", t_c," | Fahrenheit:", t_f

  if adcValue > 0.35:
    #turn on the LED
    GPIO.output("P8_12", GPIO.HIGH)
  else:
    #turn off LED
    GPIO.output("P8_12", GPIO.LOW)

  time.sleep(2) #sleep for 2 seconds then repeat
############################################################################

Pretty simple stuff really.

Some things I've done to my BBB and laptop so far in order to accomplish this:

1. Installed Putty on my laptop (SSH to BBB)
2. Updated installed applications (apt-get update & apt-get upgrade)
3. Ensure Python was installed on the BBB
4. Installed the Adafruit  BBB-IO Python library
5. Installed VNC Viewer on the laptop (to see BBB desktop)

Some projects I have in mind:

1. Brew Chamber Controller
2. Home Environment Control
3. Autonomous Quad Copter Control

In the next post we'll start the design process for the Brew Chamber Controller, be sure to check back.

Cheers!