Readme Overview (ToC)

• How to get started
  • Required hardware
  • Initial hardware setup
  • Initial software setup
  • Some helpful commands when trying out gammu
• Screenshots of one of my boxes
• Ideas to be implemented in the future
• How to install a python module

How to get started

Required hardware

• Raspberry Pi with an SD card (I recommend 8GB) and running raspbian image

• Temperature sensor (I used DS18B20 with cable and waterproof)

• Some cables, breadboard, resistances, LEDs (for testing purposes), multimeter

• Relay (I used a 5V AC250V10A 1-channel relay module)

• GSM/3G USB modem, unlocked (I used gsmliberty.net to unlock mine)

• valid SIM card (prepaid, preferably refillable via internet)

• Powered USB hub (I used this 4-port hub from i-tec, product number U2HUB412: small size and delivers enough current to power both the 3G USB modem and the RPi)

• Maybe some angled USB cables to save some space when packaging the whole thing (I bought one here)

• A rasp and a drilling machine to make the holes for the cables

• Power cable with male and female plug; cable will be cut in half to put the relay in between

Initial hardware setup

• Connect the temperature sensor to correct power/ground/data pins on the Pi using a 'pullup' resistor of 4K7 Ohm. See sensor specification and my corresponding python script. Adafruit.com also has a nice tutorial here. My temperature sensor has cable colors red=3V3, black=GND and 3rd cable (white or yellow) is DATA.

• Connect the relay to the configured (in my.cfg) GPIO pins on the Pi - see your relay specification

Initial software setup

# uninstall some useless/non-required packages
> sudo apt-get autoremove -y sonic-pi python-minecraftpi wolfram-engine
> sudo apt-get autoremove -y x11-common omxplayer scratch dillo xpdf
> sudo apt-get autoremove -y galculator netsurf-common netsurf-gtk
> sudo apt-get autoremove -y lxde-common lxde-icon-theme lxterminal hicolor-icon-theme
> sudo apt-get autoremove -y lxpanel lxpanel-data
> sudo apt-get autoremove -y
# finally clear the apt cache from all downloaded .deb packages
> sudo apt-get clean

# update RPi to latest and greatest
> sudo apt-get update
> sudo apt-get upgrade
# and if you want to run latest RPi (nightly) builds:
> sudo rpi-update

#install gammu (python library to send/read sms)
> sudo apt-get install gammu python-gammu

# if you want to use an USB Ethernet adapter to connect to the RPi
#  (for updating, configuring, debugging etc), then
#  ensure that you have the following lines (and no other lines
#  relating to interface eth1) in /etc/network/interfaces :
# allow-hotplug eth1
# iface eth1 inet dhcp

# Enable 1-wire support (for DS18B20 temperature sensor):
#  For newer kernels >= 3.18.5):
#   ensure following lines appear in your /boot/config.txt :
device_tree=bcm2708-rpi-b-plus.dtb #for RPi A+/B+
device_tree_overlay=overlays/w1-gpio-overlay.dtb
#  For older kernels:
#   ensure the following lines appear in your /etc/modules :
w1_gpio
w1_therm

# ensure that the following module is listed in /etc/modules :
usbserial

# force fsck to run upon every boot (since only way to shut down will be to cut the power)
> sudo fdisk -l # to find out your filesystem device identifier
> sudo tune2fs -c 1 /dev/<filesystem-device-identifier>

# at this point restart if you haven't done so yet:
> sudo shutdown -r now

# generate a gammu configuration and store it into .gammurc in home dir (usb modem must be connected)
> gammu-detect > ~/.gammurc

# if not yet done: generate an ssh key pair
> ssh-keygen -t rsa -C "your_email@example.com"
# now clone this git repository into the pi home folder
> cd
> git clone git@github.com:stefanthurnherr/sms-temperature-control.git

# Create your personal configuration
> cp sms-temperature-control/my.cfg.example sms-temperature-control/my.cfg
# now go through sms-temperature-control/my.cfg and adjust as needed

# add python script to root crontab (root is required to read/write GPIO channels)
# sudo crontab -e
# */15 * * * * /usr/bin/python /home/pi/sms-temperature-control/bin/say_hello.py >> /home/pi/sms-temperature-control/log/heartbeat.stdout 2>&1
# */01 * * * * /usr/bin/python /home/pi/sms-temperature-control/bin/process_sms.py >> /home/pi/sms-temperature-control/log/smsprocessing.stdout 2>&1
# */05 * * * * /usr/bin/python /home/pi/sms-temperature-control/bin/autocontrol_power.py >> /home/pi/sms-temperature-control/log/powerautocontrolling.stdout 2>&1
# @reboot      /usr/bin/python /home/pi/sms-temperature-control/bin/run_once_after_boot.py >> /home/pi/sms-temperature-control/log/afterboot.stdout 2>&1
#
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7)  OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  *  command to be executed
#

Some helpful commands when trying out gammu

# gammu version and supported features
> gammu features

# waiting for PIN?
> gammu getsecuritystatus

# enter PIN
> gammu entersecuritycode PIN -

# phone info
> gammu identify

# cell network info
> gammu networkinfo

# send sms
> echo "sms content" | gammu sendsms TEXT +1234567890 # mobile number in international format

# send USSD code (to check sim card balance etc.). Make sure to choose correct
#  section with the -s parameter, not all seem to work equally well for USSD.
> gammu -c ${HOME}/.gammurc.cfg -s 1 getussd '*100#'

Screenshots of one of my boxes

Assembled box without top cover: Final version of the box:

Ideas to be implemented in the future

• make OS run fsck upon every boot (and maybe force boot once every week?)

• Warn administrator if balance falls below (configurable) threshold (for prepaid SIM cards)

• Configurable timer function for switching relays on/off

• Add support for remote-controlled relay (TellStick? z-wave?) to be able to physically separate 5V circuit from 230V circuit. This would increase safety.

How to install a python module

For the reference, here’s how to install an additional python module (like pytz or rpi.gpio or psutil if not already available):

# install python development headers required by some packages (e.g. psutil)
> sudo apt-get install python-dev
# install python-pip using the package manager
> sudo apt-get install python-pip
# then simply install the target module, e.g. pytz:
> sudo pip install pytz