Raspberry Pi

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Raspberry Pi

With the addition of an #RFM12Pi expansion board a Raspberry Pi running emoncms can be used as a powerful emonBase base-station to log, process and visualise energy, temperature and other environmental data.

Data can be logged locally to the Raspberry Pi's SD card and/or to a remote emoncms server. Emoncms graphs and dashboards can be served from the Raspberry Pi's web-server.

RFM12Pi installed Raspberry Pi

RFM12Pi

The RFM12Pi GPIO expansion board enables the Raspberry Pi to receive or transmit data via RFM12B wireless (433/868/915Mhz) from other OpenEnergyMonitor modules such an an emonTx energy and temperature monitoring node or an emonGLCD display.

RFM12Pi Front

Technical Overview

The RFM12Pi is uses an ATtiny84 microcontroller running a modified version of JeeLabs RF12Demo to receive wireless data via RFM12B wireless transceiver and spit out the data via serial onto the Pi's internal serial UART port

The RFM12Pi board and much of the software is work of Martin Mharizanov. We have worked with Martin on the hardware design and emoncms software integration. We owe a big thank you to Martin for the work he as put into making this solution work well.

Design Files & Part List

Quantity Part
1x ATtiny84 (RF12B firmware preloaded)
2x 100nF
1x 5mm LED
2x 10K (brown, black, orange, gold)
1 x 100R (brown, black, brown, gold)
1x RFM12B (433/868 Mhz)
1x GPIO 6x2 pin header female socket
1x ISP 3x2 pin header

The RFM12Pi's Eagle CAD PCB design files, schematic and Arduino based firmware can be downloaded from Martin Mharizanov's GitHub

RFM12Pi Setup

It's recommended you read through the whole of this guide and familiarise yourself with the steps before you start the actual build.

Step 1 - Identify Components and Kit Contents

Layout and identify the components from the kit.

Rasppi.JPG


Ok, we're ready to start. Here is the PCB ready:

Rasppirfm1.jpg

Step 2 - 10k Resistors

As a general principle we're going to build up from the shallowest component. Start with the resistors. Bend each leg of the resistor over 90 degrees, right next to the body. The last colour on all of the resistors is brown - it's recommended that you align them all in the same direction and have the brown at the same end.

Rasppirfm2.jpg

Step 3 - 100R Resistor

Add the 100R resistor in exactly the same way, its colours are (brown, black, brown, gold)

Rasppirfm3.jpg

Step 4 - ATtiny84 DIL Socket

Fit the ATtiny84 DIL Socket as shown in the picture. Note that one end has a small notch in it - this signifies pin 1 and should match up with the notch on the legend. It's best to tack diagonally opposite corners to hold the socket in place whilst the rest of the pins are soldered. Make sure they are fitted flat on to the board.


Rasppirfm4.jpg

Step 5 - Green LED

Add the green LED. Ensure the long leg's (and round edge) go to the + symbol printed on the board.

Rasppirfm5.jpg


Step 6 - RFM12B RF

Place the RFM12BRF module on the pads (observe the orientation Crystal on the LEFT) and solder each pad onto the board from above.

Rasppirfm6.jpg

Step 7 - 100nF Ceramic Capacitors

Add the two 100nF ceramic capacitors one at either end of the board.

Rasppirfm7.jpg

Step 8 - ISP 3x2 pin header

Add the ISP 3x2 pin header long pins point up, short pins go into the board and are soldered.

Rasppirfm8.jpg

Step 9 - GPIO 6x2 pin header female socket

The GPIO female socket needs to go onto the bottom of the board.

Rasppirfm9.jpg

Step 10 - RF Antenna

Add the Antenna through the hole bottom right and solder in place. The length of the Antenna is dependant on the frequency of your RFM12B module. This is a piece of wire 82mm long for 868Mhz and 165mm for 433Mhz which will act as a quarter wave for the frequency. For more background information on the RFM12B see: [1]

Rasppirfm10.jpg

Step 11 - ATtiny84 Integrated Circuit

Fit the ATtiny84 IC into it's sockets. Note the spot next to pin 1 and ensure you insert it the right way round.

IC's usually come with their legs pointing slightly outwards. To get them to fit easily into the socket, you should put the legs flat on a desk and rock the IC slightly to bend the pins inwards - do that at both sides and try again to fit into the socket.

Rasppirfm11.jpg

Step 12 - Relax job done

Turn off your soldering iron and go and have a cup of tea :-)

ATtiny84

The ATtiny84 microcontroller should come pre-loaded with the required software (RFM12 Demo sketch). However if you have obtained a blank ATtiny84 you will need to upload the rf12 demo to it yourself:


The 'easy' way to do this is to flash the pre compiled hex file onto the ATtiny, this avoids having to setup the Arduino IDE for ATtiny's and having to get the correct arduino libraries etc:

  1. Download the pre compiled RF12 demo .hex file from the firmware folder on Mharizanov's RF12Pi Github Repo
  2. Power the RF12Pi board with 3.3V, this can be done from the Pi
  3. If you have an AVR ISP MKII programmer simple connect it up to the ISP header and run the following terminal commend:
    • $ sudo avrdude -c avrispmkII -p t84 -P usb -e -Uefuse:w:0xFF:m -Uhfuse:w:0xD7:m -Ulfuse:w:0xE2:m -U flash:w:ATtiny84_RF12_Demo.cpp.hex
    • This avrdude command sets the ATtiny fuses for internal 8Mhz crystal with the BOD disabled and flashes a pre-compiled RF12 Demo sketch


Alternatively you can compile the RF12 Demo sketch yourself using Arduino IDE:

  1. Setup Arduino 1.x IDE for working with ATtiny's by following our guide
  2. Download a modified version (to use software serial on the ATtiny) of JeeLabs RF12 Demo from Mharizanov's RF12Pi Github Repo
  3. Ensure you have the latest JeeLabs JeeLib Arduino library installed
  4. Power the RF12Pi board with 3.3V, this can be done from the Pi
  5. Connect up your AVR programmer to the RF12Pi's ISP header and select your programmer in Arduino IDE tools>Programmer menu
  6. In Arduino IDE select ATtiny84 @ 8Mhz (internal oscillator; BOD disabled) in the Tools>Board menu and click Tools>Burn Bootloader
  7. You are now ready to upload the RF12 Demo to the ATtiny84 using the Arduino IDE
  8. Note: if you're having trouble it might be best to go back to basics with the ATtiny on a breadboard and follow this detailed guide to working with ATtiny's.

Raspberry Pi Setup

SD card & Raspbian Linux Setup

Note: when working we the Pi we recommend shutting down the Pi properly with $ sudo halt before powering down the Pi or removing the SD card to avoid a corrupted card. We learnt this the hard way!


  1. Download Raspbian 'Wheezy' SD card image This guide was made using 18th September 2012 release.
  2. Copy SD card image on SD card using Linux tool "dd" for any other OS see Raspberry Pi tutorial
    • Insert SD card $ df -h to view mounted partition, make note of SD card device name, for me this was 'sdb'
    • Unmount SD card $ umount /dev/sdb1 you will need to change sdb to match your SD card drive. If the card has more than one partition un mount that also $ umount /dev/sdb2
    • Write the .img to the card $ sudo dd bs=4M if=~/Downloads/2012-09-18-wheezy-raspbian.img of=/dev/sdb again you will need to replace sdb with your SD card device name and modify the location and name of the image as need.
  3. Put SD card into Pi and connect network and power
  4. Find the IP address of the Pi and SSH to it $ SSH [email protected], default password is 'raspberry'
  5. Once successfully logged in run Raspbian setup $ sudo raspi-config
    • Select Expand root partition to fill SD card finish and reboot
    • One rebooted restart SSH connection and run $ sudo raspi-config again
    • Check for updates
    • Change password for user Pi to something of your choice, make it secure it will be storing your home energy data!
    • If you plan to run the Pi as a headless dataloggin emoncms server as we do then select memory-split and choose the first setting a 240/16 split, the gives the CPU more memory at the expense of graphics which we're not using
    • We also recommend selecting boot behaviour and disabling booting straight into a desktop since this increases boot time and wastes system resources. If required a desktop can be loaded with $ startx.
    • Set locale and timezone as required
    • Finish and reboot, remember to use your new password when SSH'ing back in!
  6. (optional) set a host name for the Pi to enable host name to be used instead of IP address when connection to the Pi
    • Change the default raspberrypi host name to that of your choice eg.emoncms in the file $ sudo nano /etc/hostname [Ctrl+X] then [Y] then [Enter] to save and exit
    • and in the file $ sudo nano /etc/hosts [Ctrl+X] then [Y] then [Enter] to save and exit
    • Reboot the Pi and you should be able to SSH back in with $ ssh [email protected] if 'emoncms' was your chosen host name. Note: this won't work with all routers, you might need to set the Pi as a 'Fixed Host' in the router config

Emoncms Setup

Install emoncms following this guide up to the end of section 7. Instead of emoncms3 on the OpenEnergyMonitor GitHub use $ git clone git://github.com/emoncms/emoncms.git as the GtiHub emoncms repo. This is a new 'modular' version of emoncms.

Alternatively if you prefer not to setup GitHub on the Pi you can download the .tar file directly from github and extract into /var/www:

  1. cd /var/www/
  2. sudo wget -O emoncms.tar.gz https://github.com/emoncms/emoncms/tarball/master
  3. sudo tar xvfz emoncms.tar.gz
  4. sudo mv -i emoncms-emoncms-96885fe emoncms

NOTE that the commit part of the name (the alpah numeric code) will change with every new version on github so you need to replace with the correct value when renaming the folder

Install the raspberrypi module Navigate to the emoncms modules folder $ cd emoncms/Modules. Download the Raspberry Pi emoncms module into the Modules folder $ git clone https://github.com/emoncms/raspberrypi.git

Or if not using git:

  1. cd /var/www/emoncms/Modules
  2. sudo wget -O raspberrypi.tar.gz https://github.com/emoncms/raspberrypi/tarball/master
  3. sudo tar xvfz raspberrypi.tar.gz
  4. sudo mv -i emoncms-raspberrypi-b9703b5 raspberrypi

Now carry on following the emoncms install guide section 8-10. Note: since we're using the new modular version of emoncms the first bit of step 9 should be $ cd /var/www/emoncms/ instead of emoncms3

When you have finished you should be able to browse to Http://Pi IP address or Host/emoncms and the emoncms login/register screen should appear:

Raspberrypi emoncms.png

RFM12BPi Setup

Make sure Raspberry Pi’s UART is disconnected from the console and available for programs to use it.

  1. Backup cmdline.txt $ sudo cp /boot/cmdline.txt /boot/cmdline_backup.txt
  2. Edit cmdline.txt to remove references to Pi’s UART (ttyAMA0)
    • $ sudo nano /boot/cmdline.txt
    • edit it from dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait to dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait [Ctrl+X] then [y] then [Enter] to save and exit
    • $ sudo nano /etc/inittab comment out the following line at the bottom of the file by adding a '#' at begining of: T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100 [Ctrl+X] then [y] then [Enter] to save and exit
  3. Reboot the Pi by $ sudo reboot


Install serial PHP libraries

  1. $ sudo apt-get install php-pear php5-dev
  2. $ sudo pecl install channel://pecl.php.net/dio-0.0.6
  3. $ sudo nano /etc/php5/cli/php.ini add extension=dio.so to file in the beginning of the ;Dynamic Extensions; section on line 843 [Ctrl+X] then [y] then [Enter] to save and exit
  4. Restart apache $ sudo /etc/init.d/apache2 restart
  5. Connect the RFM12Pi on to Pi's GPIO taking care to line up pin 1 as show in photo above
  6. Test the RFM12Pi is working and receiving RFM12 data by viewing it's serial output. You will need a transmitting RFM12B node to see received transmissions.
    • $ sudo apt-get install minicom
    • $ minicom -b 9600 -o -D /dev/ttyAMA0
    • The default RFM12B settings are 868Mhz and network group 210
    • Type 4b into the minicom serial window to change the RFM12B to 433Mhz and xxg to change network group with x being the desired network group.
    • With the serial window open un-plug the RFM12Pi then plug it in to see the full list of available RF12 demo commands
    • The LED on the RFM12Pi should flash to indicate a data packet received and the raw data packet should come up in the serial window.
    • To exit minicom [CTRL+ A] then [X] then [Enter]

Setup emoncms Raspberry Pi module

Config module:

  1. When you login to emoncms you should see Raspberry PI in the top menu bar, click to open the raspberry pi config page.
  2. Set your RFM12b frequency, group and RFM12BPi nodeid.
  3. Click Save so save settings and connect the RFM12BPi to the emoncms account your logged in as. One of the neat things with the module is that you dont have to manually enter the apikey to point to your account as the module does this for you.

At this stage you will see that the message box says: 'The RFM12 to PI interface script is not running, you may need to configure cron'.

Raspberrypi module2.png

Follow the following steps to run the script:

Open crontab: $ sudo nano /etc/crontab

Add this line to the end: */1 * * * * root cd /var/www/emoncms/Modules/raspberrypi && php raspberrypi_run.php

Reboot the pi with $ sudo reboot

With the script running you should now see the message box at the top of the raspberry pi module page turn green

Raspberrypi module1.png

You should now see nodes appear in your input list, setup feeds and dashboards from here as normal.

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