178 lines
7.1 KiB
Markdown
178 lines
7.1 KiB
Markdown
<!--
|
||
.. title: Google Powermeter : Step by step
|
||
.. slug: google-powermeter-step-by-step
|
||
.. date: 2010-06-15 14:34:50
|
||
.. tags: cc128,currentcost,google,mysql,powermeter,Applications
|
||
.. category:
|
||
.. link:
|
||
.. description:
|
||
.. type: text
|
||
-->
|
||
|
||
# Note: Google Powermeter is now defunct but this post will remain here for those interested.
|
||
|
||
This is a follow up to my previous [post on using Google Powermeter],
|
||
but this time I'm going to give a step by step guide to getting your data
|
||
uploaded. The only assumptions are that you have a CurrentCost monitor (note
|
||
that CurrentCost monitors are often rebadged by electricity suppliers such as
|
||
EON in the UK so check yours) and have already connected it to your computer,
|
||
want to use MQTT and that you're using Linux, or another Unix operating system.
|
||
|
||
# Retrieving the data
|
||
|
||
The first step is to get the data from the CurrentCost into the MQTT broker.
|
||
This is straightforward - simply read data from the serial port and send it all
|
||
to the broker. I have scripts to do this with mosquitto in both [perl] and
|
||
[python].
|
||
|
||
The data coming from the CurrentCost is in XML format and as well as providing
|
||
the real time power reading every 6 seconds, will also send historical data
|
||
periodically. I'm only going to deal with the real time readings here. The next
|
||
step is to reprocess the incoming data into something more manageable, then
|
||
republish it. An example of doing that is the script [cc128_parse.pl], which
|
||
assumes you're only using the main channel from the CurrentCost. If you have
|
||
multiple monitoring channels, you'll need to modify it to suit.
|
||
|
||
# Logging the data
|
||
|
||
Google limits the number of times we can send data to 6 per hour, so we have to
|
||
log the data and then send amalgamated updates. I use mysql for this - I'm
|
||
going to assume that you've got it installed and running. Log into the mysql
|
||
console using "mysql -u root", "mysql -u root -p" if you know the password, or
|
||
possibly "sudo mysql". We're now going to create a database and table to hold
|
||
the powermeter data, then add a user to access and update the data.
|
||
|
||
To create the database and table enter the following:
|
||
|
||
```
|
||
CREATE DATABASE powermeter;
|
||
USE 'powermeter';
|
||
CREATE TABLE powermeter (
|
||
`id` INT NOT NULL auto_increment,
|
||
`timestamp` INT NOT NULL,
|
||
`temperature` FLOAT NOT NULL DEFAULT 0.0,
|
||
`ch1` INT NOT NULL DEFAULT 0,
|
||
PRIMARY KEY (`id`),
|
||
UNIQUE KEY `timestamp` (`timestamp`)
|
||
) ENGINE=InnoDB DEFAULT CHARSET=utf8;</pre>
|
||
```
|
||
|
||
Note that there's a column there for the temperature as well.
|
||
|
||
To add the user and grant access to the database:
|
||
|
||
```
|
||
CREATE USER 'powermeter'@'localhost' IDENTIFIED BY '<your password>';
|
||
GRANT ALL ON powermeter.* to 'powermeter'@'localhost';
|
||
```
|
||
|
||
Finally, you'll need to get data into this database. My script
|
||
[cc128_log_mysql.pl] subscribes to the data from cc128_parse.pl and logs it
|
||
into the database. You'll need to edit it to have the correct database
|
||
details.
|
||
|
||
If you already have your power data published to an MQTT topic, it's quite
|
||
likely that you won't have it in the same format that I use above. If this is
|
||
the case, you will need to modify cc128_log_mysql.pl. Assuming your data coming
|
||
in over MQTT is just the power reading, then you can replace this:
|
||
|
||
```
|
||
@vals = split(/,/, $line);
|
||
$timestamp = @vals[0];
|
||
$temperature = @vals[1];
|
||
$ch1 = @vals[2];
|
||
```
|
||
|
||
with this:
|
||
|
||
```
|
||
$timestamp = time();
|
||
$temperature = 0;
|
||
$ch1 = $line;
|
||
```
|
||
|
||
You can of course leave the temperature column out completely if you prefer.
|
||
|
||
# Registering with Google Powermeter
|
||
|
||
Before you can send any data to Google, you need to register your device with
|
||
them. This would normally be done automatically by your device, but because
|
||
we're doing things ourselves we need to do it manually. See [2cheap2meter] and
|
||
the links it provides for more details.
|
||
|
||
We first need to decide on a few parameters for our device:
|
||
|
||
* Manufacturer (e.g. CurrentCost)
|
||
* Device model (e.g. CC128 or Envi)
|
||
* Device id (e.g. Serial number or your own made up string, 1234)
|
||
* Number of channels to log (e.g. 1)
|
||
|
||
We can then construct an address which you will paste into your web browser:
|
||
|
||
```
|
||
https://www.google.com/powermeter/device/activate?mfg=CurrentCost&model=CC128&did=1234&dvars=1
|
||
```
|
||
|
||
`dvars` here is the number of channels (or monitors) that we wish to register.
|
||
If you have more than one channel logging, change the number accordingly - bear
|
||
in mind that you'll have to modify just about everything else in this post to
|
||
match. You will need to remember the values you put here for later.
|
||
|
||
Visiting that link will take you to the activation page, which you should
|
||
complete. After you have done this, you will be presented with authorisation
|
||
information for your new device. The piece of information we need is the 32
|
||
character string contained between "token=" and "&path" (the authorisation
|
||
token) as well as the 20 digit number after "&path=/user/" (your google
|
||
powermeter id).
|
||
|
||
# Sending the data
|
||
|
||
I have a script [google_powermeter_update.pl] that will query the database for
|
||
readings from the past 15 minutes and then send them. You'll need to edit the
|
||
script to put the correct database details, power meter id, authorisation token
|
||
and device details. To set it to run every fifteen minutes, I use cron. Either
|
||
add an entry to your own crontab by running "crontab -e" then entering the
|
||
following line:
|
||
|
||
```
|
||
*/15 * * * * /path/to/google_powermeter_update.pl > /dev/null
|
||
```
|
||
|
||
Or by creating a file containing the line below and copying it to
|
||
/etc/cron.d/powermeter_update.cron.
|
||
|
||
```
|
||
*/15 * * * * nobody /path/to/google_powermeter_update.pl > /dev/null
|
||
```
|
||
|
||
In both cases, you can change the output redirection from "/dev/null" to e.g.
|
||
"/tmp/powermeter" to allow you to check any error codes in case of a problem.
|
||
|
||
Now go to <http://www.google.com/powermeter/site/> to check your data! Here's
|
||
an example of mine:
|
||
|
||
[](/blog/uploads/2010/06/powermeter-example.png)
|
||
|
||
# Possible changes
|
||
The above description and scripts aren't ideal - if you lose your internet
|
||
connection then data will still be recorded but won't be sent to google. One
|
||
possible change would be to add a column to the database to list whether that
|
||
particular piece of data had been sent or not, which would allow all data to
|
||
eventually be sent and deleted afterwards if desired.
|
||
|
||
A second way around this would be to make use of the historical data that the
|
||
CurrentCost monitors use. This could also be a way of reducing the need to log
|
||
things ourselves.
|
||
|
||
# Conclusion
|
||
I hope this is of use to you - please let me know if you have any problems with
|
||
any of the above steps.
|
||
|
||
[post on using Google Powermeter]: /blog/2010/03/google-powermeter/
|
||
[perl]: http://bitbucket.org/oojah/mosquitto/src/tip/misc/currentcost/cc128_read.pl
|
||
[python]: http://bitbucket.org/oojah/mosquitto/src/tip/misc/currentcost/cc128_read.py
|
||
[cc128_parse.pl]: http://bitbucket.org/oojah/mosquitto/src/tip/misc/currentcost/cc128_parse.pl
|
||
[cc128_log_mysql.pl]: http://bitbucket.org/oojah/mosquitto/src/tip/misc/currentcost/cc128_log_mysql.pl
|
||
[2cheap2meter]: http://2cheap2meter.blogspot.com/2010/03/setting-up-google-powermeter.html
|
||
[google_powermeter_update.pl]: http://bitbucket.org/oojah/mosquitto/src/tip/misc/currentcost/google_powermeter_update.pl
|