Logging Rainforest RAVEn/EMU-2 Data to ThingSpeak (node.js on Raspberry Pi)

Last year, I bought a Rainforest EMU-2 energy monitor.  It wirelessly talks via zigbee to the smart energy meter that SCE installed at my house a couple of years ago. Unfortunately, its logging capabilities are rather primitive. All it does is give you a crude bar graph of the current and previous day’s usage. SCE actually has fairly detailed logs on their website, which you can access without buying your own energy monitor, but it’s cumbersome to log into their website and navigate down to the pages. Fortunately, a nice feature of the EMU-2 is that it has a USB port which behaves exactly like the Rainforest RAVEn, so you can read out the data into a computer and log it. I decided to hook up the EMU-2 to a Raspberry Pi, and log the data to ThingSpeak with node.js.

Step 1: Install node.js on Raspberry Pi

Unfortunately, the version of node.js that installs via apt-get on the Adafruit Occidentalis distro that I run on my Raspberry Pi is rather old (v 0.6.19), and won’t work with our code. I had to manually install from the nodejs repository:

wget http://nodejs.org/dist/v0.10.22/node-v0.10.22-linux-arm-pi.tar.gz
tar xzf node-v0.10.22-linux-arm-pi.tar.gz
cp -R node-v0.10.22-linux-arm-pi/bin /usr/local
cp -R node-v0.10.22-linux-arm-pi/lib /usr/local
cp -R node-v0.10.22-linux-arm-pi/share /usr/local
echo export NODE_PATH=/usr/local/lib/node_modules:/usr/local/lib/node_modules/npm/node_modules >> ~/.bashrc
source ~/.bashrc

I’m using node.js v0.10.22 because it works, and that’s the version that I’m using on my Debian development machine. I tried to install the latest, v0.11.11, but ran into all sorts of errors.

Step 2: Install node.js libraries

My RAVEn logging script depends on some libraries, serialportthingspeakclient, and xml2js, which we can install via npm:

npm install -g serialport thingspeakclient xml2js

Step 3: node.js code

The RAVEn XML API is fairly simple. To make things even simpler, I found that stormboy had already written a node.js library to decode it and github: stormboy/node-raven. node-raven reads data from RAVEn and uploads it to an MQTT server, so I had to modify the code to upload to ThingSpeak. Below is my script:

[code language=”java”]
* Reads energy data from a smart meter via a RAVEn RFA-Z106 dongle (http://www.rainforestautomation.com/raven) and uploads to ThingSpeak.
hacked from stormboy’s node-raven https://github.com/stormboy/node-raven
by Sam C. Lin

var serialport = require("serialport"),
ThingSpeakClient = require(‘thingspeakclient’),
xml2js = require(‘xml2js’);

process.on(‘uncaughtException’, function(err) {
// handle the error safely

var TRACE = true;

// RAVEn’s serial port
var ravenSerialPath = ‘/dev/ttyUSB0’;

// thingspeak parameters

var tsclient = new ThingSpeakClient();
tsclient.attachChannel(channelId, { writeKey:apiKey});

// date offset for RAVEn which presents timestamp as seconds since 2000-01-01
var dateOffset = Date.UTC(2000, 0, 1);

var dailyNet = 0;
var dailyNetSentDate = 0;

var Raven = function(serialPath) {
var self = this;

// configure the serial port that the RAVEn USB dongle is on.
this.serialPort = new serialport.SerialPort(serialPath, {
baudrate: 115200,
databits: 8,
stopbits: 1,
parity: ‘none’,
parser: serialport.parsers.readline("\r\n")

this.serialPort.on("open", function() {

* Get the connection status between the USB device and the power meter
Raven.prototype.getConnectionStatus = function() {
var queryCommand = "<Command><Name>get_connection_status</Name></Command>\r\n";

* Get information about the device
Raven.prototype.getDeviceInfo = function() {
var queryCommand = "<Command><Name>get_device_info</Name></Command>\r\n";

* Query the amount of energy used or fed-in.
Raven.prototype.getSumEnergy = function() {
var queryCommand = "<Command><Name>get_current_summation_delivered</Name></Command>\r\n";

* Get the power currently being used (or fed-in)
Raven.prototype.getSumPower = function() {
var queryCommand = "<Command><Name>get_instantaneous_demand</Name></Command>\r\n";

Raven.prototype.getMessage = function() {
var queryCommand = "<Command><Name>get_message</Name></Command>\r\n";

Raven.prototype.getTime = function() {
var queryCommand = "<Command><Name>get_time</Name></Command>\r\n";

Raven.prototype.getCurrentPrice = function() {
var queryCommand = "<Command><Name>get_current_price</Name></Command>\r\n";

Raven.prototype.close = function() {

// handle serial port open
function openHandler (self) {
var parser = new xml2js.Parser();
var buffer = ""; // read buffer.

if (TRACE) {
console.log(‘serial device open’);

// add serial port data handler
self.serialPort.on(‘data’, function(data) {
buffer += data.toString() + "\r\n"; // append to the read buffer
if ( data.toString().indexOf(‘</’) == 0 ) { // check if last part of XML element.

// try to parse buffer
parser.parseString(buffer, function (err, result) {
if (err) {
console.log("err: " + err);
console.log(‘data received: ‘ + buffer);
else if (result.InstantaneousDemand) {
var timestamp = parseInt( result.InstantaneousDemand.TimeStamp );
timestamp = new Date(dateOffset+timestamp*1000);
var demand = parseInt( result.InstantaneousDemand.Demand, 16 );
demand = demand < 0x80000000 ? demand : – ~demand – 1;
if (TRACE) {
console.log("demand: " + timestamp.toLocaleString() + " : " + demand);
var tsData = new Object();
tsData = { field1: demand };
else if (result.CurrentSummationDelivered) {
var timestamp = parseInt( result.CurrentSummationDelivered.TimeStamp );
timestamp = new Date(dateOffset+timestamp*1000);
var used = parseInt( result.CurrentSummationDelivered.SummationDelivered, 16 );
var fedin = parseInt( result.CurrentSummationDelivered.SummationReceived, 16 );
var curDate = timestamp.getDate();
var net = used – fedin;

if (dailyNet == 0) {
dailyNet = net;
dailyNetSentDate = curDate;

if (TRACE) {
console.log("sum: " + timestamp.toLocaleString() + " : " + used + " – " + fedin);

var tsData = new Object();
tsData = { field2: net,field3: used,field4: fedin};

// only send daily net once a day
if (curDate !== dailyNetSentDate) {
tsData.field5 = net – dailyNet;
dailyNet = net;
dailyNetSentDate = curDate;


else if (result.ConnectionStatus) {
if (TRACE) {
console.log("connection status: " + result.ConnectionStatus.Status);
else {
if (TRACE) {
console.dir(result); // display data read in
buffer = ""; // reset the read buffer

var raven = Raven(ravenSerialPath);

Before you can run the script, you must ravenSerialPath, channelId, and apiKey to match your own configuration. Node that the code contains several getters which I don’t use, because by default, my EMU-2 sends out the data via the USB serial port at regular intervals.

Step 4: ThingSpeak Channel Configuration

Next, you must create a new ThingSpeak channel with 5 fields:

Step 5: Run our node.js script

node raven-log.js &

Below are the live data from my ThingSpeak channel: Rainforest RAVEn Logging Demo

I will be updating the code from time to time. You can always get the latest version from github: lincomatic/raven-thingspeak

How to use a WiFi Dongle with Raspberry Pi

My house isn’t wired for Ethernet, so I needed to get my Raspberry Pi networked via WiFi.  USB WiFi dongles are cheap, and can easily be found for less than $10.  I just happened to have an Airlink101 AWLL6075 laying around.  By coincidence, it uses the RTL8191SU chipset, and the official Raspbian distribution is preloaded with the appropriate driver (module r8712u).

USB WiFi dongles use quite a bit of current, and some web references said that they could only be used with the RPi via a powered USB hub.  However, some people reported success without the hub.  I couldn’t find a working powered USB hub in my house, so I tried connecting my dongle directly to my RPi.

While googling around for instructions on how to configure Raspbian for my WPA2-PSK network,  I found several different sets of instructions for configuration, and none of them worked.  After wasting a whole afternoon with no luck, I found out that early RPi boards had 140mA polyfuses to limit current draw on the USB ports. In addition to limiting the current too severely, the polyfuses lower the voltage below spec.  Therefore, later boards have 0 ohm resistors instead of the polyfuses.  Here is an official blog post which shows that the later boards don’t have the fuses:  http://www.raspberrypi.org/archives/1929

The fuses in question are F1 and F2.  The polyfuses are green, and have 14 written on them.  The 0 ohm resistors are black.  If your RPi has the resistors, then you don’t need to modify it. My board had the polyfuses, so I shunted them by soldering in jumper wires:

Bingo! The WiFi fired right up and connected to my AP on the first boot after the fix.

The easiest way to configure the SSID and password for your network is to edit the file /etc/network/interfaces:

$ sudo nano /etc/network/interfaces

Add the following lines to the file:

auto wlan0
iface wlan0 inet dhcp
wpa-ssid “YOURSSID”

Substitute your network’s SSID and password in the quotes above.  If present, remove the 70-persistent-net.rules file:

$,sudo rm /etc/udev/rules.d/70-persistent-net.rules

Upon rebooting, your WiFi should connect up automatically.  If you want to start it without rebooting, type

$ sudo ifup wlan0

Here are some useful commands related to your WiFi configuration:

$ iwlist wlan0 scan

scans for and displays available WiFi networks.

$ iwconfig

shows WiFi connection info, such as ESSID, bit rate, and frequency.

$ ifconfig

displays network information, such as IP number, MAC address, and packet errors.

How to Install Emacs on Raspberry Pi

I just got my Raspberry Pi up and running on Raspbian, and was finding nano, the pre-installed text editor a bit lacking.  I’ve been using Emacs since college, and decided to get it up and running on my Pi.  It turns out that it’s quite simple to install GNU Emacs:

$ sudo apt-get install emacs

If the above command fails and complains of missing packages, try

$ sudo apt-get upgrade

and then retry installing emacs (thanks to Tom Sargent for this tip).

Emacs users typically prefer their ctrl keys to reside where the Caps Lock key typically resides on most PC keyboards.  To swap the left Ctrl and Caps Lock keys, edit /etc/default/keyboard, and find the line XKBOPTIONS line.  If it’s currently empty, just replace it with


if the line already has some other options in it, simply separate the options with a comma, e.g.:


To make the change effective, type:

$ sudo dpkg-reconfigure -phigh console-setup

They keyswap will persist across reboots, and works in both virtual text consoles, and X-windows.

Raspberry Pi Case

I was not fast enough to get an order in for a Raspberry Pi on launch day.  Fortunately, a kind friend of mine thought of me, and bought an extra one for me.  I received it yesterday, and printed this case:

The case I made is a copy of HansH’s excellent Raspberry Pi case, modified with a slot that added on the top to accomodate access to the GPIO pins.  I uploaded it to Thingiverse:  Raspberry Pi Case with GPIO Access.  Here’s the first sucessful boot of my Raspberry Pi:

It looks so tiny sitting in front of my 52″ plasma.  I was pleasantly surprised to see it boot up at full 1080 resolution.  At first, I thought the HDMI port was bad, because it didn’t work with a cable that I know is good, but it turns out the Pi is just picky about HDMI cables.  I swapped in a different one, and it worked.  Now, I have a lot of reading to do… yet another gadget to play with…