Raspberry Pi

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Revision as of 19:49, 24 March 2013 by Glyn.hudson (Talk | contribs) (Updates & Work in Progress)

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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. The RFM12Pi expansion board can be purchased from the OpenEnergyMonitor shop

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 Harizanov. 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 Assembly

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. The colours for the 10K resistor are (brown, black, orange, gold).

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 PCB print. Make sure the socket is fitted flat on 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 its 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 firmware (RFM12 Demo sketch). If you have bought the RFM12pi from the OpenEnergyMonitor Shop jump ahead to #RaspberryPi Setup. However if you have obtained a blank ATtiny84 you will need to upload the rf12 demo firmware 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 simply 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

There are two options to setup your Pi with emoncms and RFM12Pi. You can set up the system from scratch following all the steps in the section below, or you can quickstart by downloading our ready-to-go SD card image.

Using the ready-to-go SD card image

Documentation for this section is in progress....may be incomplete or incorrect

This 'ready-to-go' SD card image is designed for a 2GB SD card. It's based on Raspbian 'Wheezy' (Sep 2012 release), and has all the needed server components and emoncms installed and configured to receive wireless data from OpenEnergyMonitor and JeeNode modules using the RFM12Pi hardware connected to the GPIO header on the Pi. A few additional setup steps are required/recommended:

We recommend using SSH to access the Pi terminal window remotely. That way, you won't need a monitor connected to the Pi

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

  1. Download the ready-to-go SD card image here (514Mb
  2. Extract .img from .zip file, the emoncmspi.img uncompressed image size is 2GB
  3. Write image to 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
  4. Write to SD card using sudo dd bs=4M if=emoncmspi.img of=/dev/sdb
  5. Insert card into the Pi and connect Ethernet and power
  6. ssh to the Pi using ssh [email protected] and password raspberry. You will need to replace the IP address with the local IP address of your Pi. This can be found by looking at the DHCP table in your router. Alternatively, you can use a network scanning app such as Fing (android), iNet (Mac), iNet (iPhone) to scan your network.
  7. Optional but recommended: run sudo raspi-config and set a number of options:
    • If you card >2Gb Expand the root partition to fill SD card, this will give you more space to log data
    • Set your timezone
    • Optional: set a 'Modest' over clock setting to improve performance
    • Optional: run update raspi - caution this may break things!
    • Save and reboot
  8. From another computer on the same local network navigate to the Pi's IP address
  9. If all is working well you should see the emoncms login screen
  10. Login to emoncms using username raspi and password raspberry
  11. Once logged in navigate the the Raspberry Pi config section (top left tab)
  12. If you see an error message stating that the script is not running you will need to restart cron, this seems to be needed when loading up a fresh SD card.
    • ssh to the Pi (instructions above)
    • once logged in via ssh enter $ ps -A | grep cron to view the current process list
    • To kill the cron process, enter $ sudo kill xxx replacing xxx with the cron process number from the list above. There might be more than one cron process running. Repeat this step until all cron processes have been killed. $ ps -A can be ran again to check.
    • The PHP script must be killed within 1 minute before it gets re-spawned. To do this, enter $ sudo top then kill xxx where x is the php process number (usually at the bottom of the list, press 'down key' to scroll down).
    • reboot the pi & sudo reboot
  13. Once the Pi restarts log back into emoncms using a web browser and navigate the the Rasbperry Pi section, if all has gone well you should see a message stating that the script is running.
  14. Enter in your RFM12B wireless frequency and network group for your module and network. We recommend you use 15 as the Pi's node ID. See recommended node ID allocation table at bottom of this page.
  15. Enter in your remote emoncms login details if you want you data to be mirrored to a remote sever
  16. After clicking save, head over to the Inputs section. You should now see your wireless nodes appear
  17. Map the Inputs through to Feeds using the input processes of your choice. See using emoncms documentation for info.


  1. Note: all passwords on the pre-configured system (eg. MYSQL,SSH should be raspberry)


If you're a Linux guru, and know how we can make the above 'pre-built SD card' setup easier, (ideally plug and play), please get in touch with us!

Configuring from scratch

In this section, we will install the operating software onto the RaspberryPi and configure it remotely. To do this we will use SSH. You will need to have an SSH client program. Linux and Mac OS X already have this installed (on a mac use the Terminal App - Applications/Utilities/Terminal, for Windows get Putty or an alternative.

Note: when working we the Pi we recommend shutting down the Pi properly with $ sudo halt before powering down 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 (sudo reboot) 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

Now that you have your RaspberryPi up and working, we are now going to install the Emonncms software. To do this we need to install the webserver software (Apache), the database (MySQL) as well as the Emoncms scripts (written in a programming language called php).

It is highly recommended that you copy and paste the command line code to avoid making mistakes (the most common cause of most errors).

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:


Be aware that installing Emoncms to any directory other than /var/www/ will break the data import scripts. (see http://openenergymonitor.org/emon/node/1329#comment-7526).


  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 alphanumeric code) will change with every new version on github so you'll need to replace that part of the name 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 your Raspberry Pi’s UART is disconnected from the console and available for programs to use.

  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
  3. Edit inittab
    • $ 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
  4. 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

  1. Restart apache $ sudo /etc/init.d/apache2 restart


Test the RFM12Pi is receiving data

  1. Connect the RFM12Pi to your Pi's GPIO taking care to line up pin 1 as show in photo above
  2. 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 xxxg 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 was received and the raw data packet should show up in the serial window.
    • To exit minicom [CTRL+ A] then [X] then [Enter]


Important info from M. Harizanov if you want to use Minicom for debugging purposes:

Regarding minicom, I suspect you have the PHP cron job that emoncms starts running in the background. you can't use both emoncms's cron and minicom at the same time, or you'll see gibberish. To stop the cron job, edit the crontab and comment out the line that runs every minute, then reboot. Glyn and I have had that same issue before, it was easily resolved by stopping the cron job - the serial port can't be accessed both by emoncms and minicom at the same time.

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.

SD Card Speed & Benchmarking

We have found that emoncms works better on some SD card than others even if the SD cards are both marked as class 4. This section is for listing the make, model, capacity and actual speed of your SD card. The speed can be measured using sudo hdparm -t /dev/sdb assuming your SD card is on sdb.

  • Kingston 4GB Class 4: 50 MB in 3.09 seconds = 16.20 MB/sec - emoncms is slow
  • ScanDisk 4GB Class 4: 50 MB in 3.02 seconds = 16.55 MB/sec - emoncms works well
  • ScanDisk 8GB Class 10: 54 MB in 3.04 seconds = 17.74 MB/sec
  • Samsung SDHC Essential 32GO Class 10: 70 MB in 3.02 seconds = 23.21 MB/sec - emoncms looks fine

Troubleshooting

If you have followed these instructions and got to the end and it hasn't worked, don't worry, you won't be alone! Try reading through the instructions carefully again, the main reason for errors are typo's and missed steps. Try to Copy and Paste the command lines into the RaspberryPi terminal window to avoid these. If you are still having problems, ask a question on our friendly forums.

When posting on the forum please give as much information about what you have done and what you see as you can. Please also include information about what your monitoring setup is.

Updates & Work in Progress

We are currently looking into integrating into the emoncms Raspberry Pi Module the function to allow the RFM12Pi to send the current time to the emonGLCD, see forum thread. This currently creates an issue where the serial string can get corrupted and the ATiny interprets this as a command to change the RFM12B network or node IDE. To solve this Martin has released a firmware update for the ATtiny84 which allows the 'locking' of the RFM12B settings:


Martin Harizanov ATtiny84 firmware update (22/12/12): http://harizanov.com/2012/12/rfm2pi-firmware-updates/

-Ability to lock RFM12B settings

-Fix for ACKS timing

RFM12Pi V2