Syndicate content
Open-source tools for energy monitoring and visualisation
Updated: 3 min 31 sec ago

China Shenzhen Electronic Market & HopeRF Factory Visit

Mon, 21/09/2015 - 03:06

For the past two weeks I have been travelling out to the South of China from the UK via overland travel. I have always wanted to visit China but could not bring myself to justify the carbon impact of flying*. My journey took me from the UK to Moscow via European trains then the Trans Siberian Railway across Russia and Mongolia to China. It was a fantastic adventure, we broke up the travel by stopping off in various locations on route. I have posted a couple of blog posts on my personal blog accounting the journey.

Even though at OpenEnergyMonitor we do most of our manufacturing and assembly locally in the UK there are many components that are only possible to source in China e.g CT sensors, power adapters and RF modules. In fact most electronic components originate in some way from a factory in China. Even though we do our SMT assembly and PCB fabrication in the UK we still rely heavily on Chinese manufacturing. For heavy items like power adapters and CT sensors we purchase in bulk (pallet load) and ship via ocean freight rather than air cargo to reduce carbon footprint.

I wanted to visit China to experience the culture and see for myself the working conditions in the factories that supply some of the components we use. No doubt attempting to trace back every factory and company in a supply chain for a complex items such as electronic components is a big task, something large corporation (think Apple and Samsung) have struggled with. We have all heard the horror stories of overworked and under-age employees in Chinese electronic factories.

My epic train ride to China rolled me into the North of China and Beijing first. After being a tourist for a day and visiting the very 'great' Great Wall of China I took a fast train down to Shenzhen. This train was seriously impressive, cruising at a smooth 307 Km/hr. I was glued to the window watching countryside and cities larger than London that I had not heard of fly by. I was aware that China is home to many, many people however this was really evident looking out the window watching huge cities and row upon row of skyscrapers flash by. In every town town and city it seemed many more tower blocks were in the process of being built, there is no doubt that China is undergoing an economic boom. After 8hrs of fast train blur we arrived in Shenzhen, nicknamed together with it's neighbouring city Guangzhou as the ‘factory of the world’; it's almost certain that the laptop/tablet/phone you are using to read this was made in factories in these cities.

During my time in Shenzhen I visited the world's largest electronic component market and the HopeRF factory where the RFM12B and RFM69CW RF modules that we use are designed and manufactured. I didn't manage to visit the factory where our CT sensors are manufactured since this factory was located in the north of China, however I did post up some photos I was sent from inside the factory a while back. 
Visiting the electronics market in downtown Shenzhen was a fantastically crazy experience. It was amazing to see all types of components carefully organised under the glass counters. There is something satisfyingly tactile about being able to hold different types of connectors and switches to compare quality and dimensions and chat to the seller about the pros, cons and cost of each item. Assuming you could speak Mandarin shopping for components here would be a far more social experience than an online parametric search tool! Obviously prices for these components are significantly cheaper than in the West.

Electronic component market in downtown Shenzhen (I'm pictured with the seller of encapsulated DS18B20 temperature sensors that we stock)Before I started working in electronic manufacture I assumed (like I think many people do) that most electronic manufacture is performed by robots. This is mainly true for pick-and-place assembly, however there are many more manufacturing steps which require significant human effort such as thru-hole soldering, testing and final assembly.

I am happy to report that the HopeRF I visited was clean, air conditioned and all employees were at least the minimum age, paid at least the minimum wage and worked 8am - 6pm with a 2hr lunch / siesta break. Overtime is common but employees are paid accordingly. All employees I met seems happy, although I did happen to arrive just as they were leaving on their lunch break! On the wall in the corridor there was a notice board with photos showing various company employee group outings including activities such as hill walking, running, swimming and group dinners. I also noticed an employee suggestion box.

I did get a chance to speak to an engineer at Hope RF who is involved in the design of new modules. As I had presumed the RFM69CW using a more standard IC package is much more suited to reflow soldering and less susceptible to humidity ingression than the older RFM12B design that often used a 'black blob' IC package. Second photo down on the left shows a naked RFM12B before receiving it's 'blob' dressing! Interestingly I learned (and witnessed!) that each and every single module is hand tested before leaving the factory. Modules that fail the test are debugged by hand. I was told that they have no plans to halt manufacture of the older RFM12B modules as long as there is demand.

HopeRF factory in Shenzhen where RF modules are designed, manufactured & tested.

* Travelling via train emits 80-90% less carbon then flying [Source:].

The international 'safe' level of emissions per person is around 2T/yr to contain global temperature changes at or below 2 deg C which will 'hopefully' keep runway climate change and subsequent rise in sea levels at bay. Return fight from London to Málaga will emit 2/3T of carbon per person

6.5T to Auckland Australia or 2T to New York. [Source: Only Planet, Ed Gillespie 2014]
Categories: Blog

How to setup a WIFI Hotspot on an EmonPi

Wed, 09/09/2015 - 17:58
This guide details how to setup a WIFI Hotspot using the Edimax USB WIFI adapter on an EmonPi or EmonBase to make it possible to connect directly to an EmonPi from a tablet or computer without the need for a router or internet connection.

The guide is based on Dave Conroy's guide here but also covers setting up a DHCP server rather than ethernet to WIFI bridge.

There are 3 pieces of software that need to be installed to get this to work:
  • hostapd – WIFI Hotspot
  • edimax version of hostapd
  • isc-dhcp-server – DHCP Server
1) Install hostapd and isc-dhcp-server

sudo apt-get install hostapd isc-dhcp-server

2) Install Edimax version of hostapd (this uses Dave Conroy's precompiled binary, see Dave Controy's tutorial for information on compiling this yourself)

sudo mv /usr/sbin/hostapd /usr/sbin/hostapd.bak
sudo mv hostapd /usr/sbin/hostapd.edimax
sudo ln -sf /usr/sbin/hostapd.edimax /usr/sbin/hostapd
sudo chown root.root /usr/sbin/hostapd
sudo chmod 755 /usr/sbin/hostapd

3) Configure /etc/network/interfaces

Open the network interfaces file to edit:

sudo nano /etc/network/interfaces

Replace content with:

auto lo
iface lo inet loopback

auto eth0
allow-hotplug eth0
iface eth0 inet manual

# auto wlan0
# allow-hotplug wlan0

iface wlan0 inet static

# wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

auto wlan1
allow-hotplug wlan1
iface wlan1 inet manual
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

4) Configure /etc/hostapd/hostapd.conf
Open hostapd config file with:

sudo nano /etc/hostapd/hostapd.conf

Add the following lines to hostapd.conf


Manual start: sudo hostapd -dd /etc/hostapd/hostapd.conf

5) Configure /etc/default/hostapd

sudo nano /etc/default/hostapd

Set DAEMON_CONF="/etc/hostapd/hostapd.conf"

6) Configure /etc/dhcp/dhcpd.conf
Open dhcpd config file:

sudo nano /etc/dhcp/dhcpd.conf

Add the following to the end of the file:

lease-file-name "/home/pi/data/dhcpd.leases";
subnet netmask {

7) Configure /etc/default/isc-dhcp-server

sudo nano /etc/default/isc-dhcp-server 

Remove the comment from DHCPD_CONF, DHCPD_PID and then set the INTERFACES to wlan0, or replace with the following:

# Defaults for isc-dhcp-server initscript
# sourced by /etc/init.d/isc-dhcp-server
# installed at /etc/default/isc-dhcp-server by the maintainer scripts
# This is a POSIX shell fragment

# Path to dhcpd's config file (default: /etc/dhcp/dhcpd.conf).

# Path to dhcpd's PID file (default: /var/run/

# Additional options to start dhcpd with.
#       Don't use options -cf or -pf here; use DHCPD_CONF/ DHCPD_PID instead

# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
#       Separate multiple interfaces with spaces, e.g. "eth0 eth1".

8) Edit /etc/rc.local

sudo nano /etc/rc.local

Add before exit 0 the following lines to tell the wlan interface to use ip address and then start the isc-dhcp-server:

sudo ifconfig wlan0 
sudo service isc-dhcp-server start

9) Copy existing dhcpd.leases file to writeable partition on /home/pi/data

sudo cp /var/lib/dhcp/dhcpd.leases /home/pi/data

Thats it restart your emonpi/emonbase to finish and then connect to network EmonPi with password: raspberry

Useful blogs, guides and forum threads that I used to work out how to set up the above:
Categories: Blog

Pulse counting with the RFM69PI and RaspberryPi EmonBase basestation

Sun, 06/09/2015 - 22:08
The latest version of the RFMPi Adapter board made much of the spare digital and analog IO available for use directly on the RFMPi adapter board. D3 is one of the digital inputs available and can have an interrupt attached (INT 1) which makes it useful for pulse counting.

By connecting a optical pulse sensor directly to the rfm69pi adapter board this can make a relatively low cost solution for internet connected pulse counting (or local logging to emoncms running on the raspberrypi).


1) The RJ45 connector on the optical pulse counter needs to be removed and individual wires exposed. Connect the red wire to 3.3V, the black wire to GND and the blue wire to D3:

2) To use the rfm69pi adapter with pulse counting the pulse counting firmware needs to be uploaded to the rfm69pi adapter board, the steps to upload this firmware are:
  1. SSH into your raspberrypi running the standard OpenEnergyMonitor image.
  2. Place raspberrypi in write mode:
    $ rpi-rw
  3. Stop emonhub:
    $ sudo service emonhub stop
  4. Pull in latest changes to RFM2PI git directory:
    $ cd RFM2PI
    $ git pull
  5. Upload pulse counting firmware:
    $ avrdude -v -c arduino -p ATMEGA328P -P /dev/ttyAMA0 -b 38400 -U flash:w:/home/pi/RFM2Pi/firmware/RFM69CW_RF_Demo_ATmega328/RFM69CW_RF12_Demo_ATmega328_Pulse/RFM69CW_RF12_Demo_ATmega328_Pulse.cpp.hex
  6. Start emonhub:
    $ sudo service emonhub start
Next login to the local emoncms installation on the raspberrypi and navigate to the emonhub.conf editor. Add the following node definition in the nodes section of emonhub.conf:

    nodename = rfmpi_pulse
    firmware = RFM69CW_RF12_Demo_ATmega328_Pulse
    hardware = rfm69pi
       names = power,count
       datacodes = h,L
       scales = 1,1
       units = W,Wh 

The pulse count is accumulated on the rfm69pi until the rfm69pi is reset either by an outage or by turning off and on the power.

To record the total accumulated pulse count in emoncms use the wh_accumulator input process which detects resets continuing the total pulse count accumulation from the last value before the reset.
Categories: Blog

At Watt Cost? A review of the emonPi Raspberry Pi based energy monitor

Fri, 04/09/2015 - 16:10
At Watt Cost ?A review of the emonPi, a Raspberry Pi based energy monitoring system developed by OpenEnergyMonitor, by Lionel Smith :
Measurement is the first step that leads to control and eventually to improvement. If you can’t measure something, you can’t understand it. If you can’t understand it, you can’t control it. If you can’t control it, you can’t improve it.”
― H. James HarringtonDo we know how much electricity can be saved by using low energy lighting such as LED's or how much electricity is saved by turning off lighting when not in use?Finding out how much electricity is being used by one or all of your appliances, is the first step in being able to cut down on consumption, and in doing so spend less on electricity. It goes without saying that reducing your consumption equates to doing your bit towards creating a sustainable world. Glyn Hudson, Trystan Lea and the rest of the team at have developed some monitoring technology to help us understand and optimise our energy consumption and generation. This allows us to approach the problem of energy consumption in a logical and informed way.The Raspberry Pi isn't great at measuring analogue voltages, so various Arduino based measurement boards have been developed which process and digitise the inputs and transfer them to the Pi. In early 2014 an idea was born to create a shield which plugged directly onto a Raspberry Pi to make a single unit energy monitoring solution, primarily aimed at domestic users. A whole bunch of discussions and a fair amount of blood, sweat and tears culminated in a Kickstarter campaign which raised £24,723 to help bring the project to lifeThis piece of kit is dubbed the emonPi, which is a Raspberry Pi based, open-source, web-connected, energy & environmental monitor. This unit gives you the ability to measure home energy, solar PV, heatpump generation and temperature.Everything on the site is fully open-source, which means you are free to tinker and improve to suit your needs. There is a very active community so help is readily available.Aside from the obvious current and voltage values, temperature and humidity can also be measured by adding the appropriate nodes. All this information is then formatted on the Pi and either stored locally or uploaded via an Internet connection to a hosted application called EmonCMS. Once you've built up some data, various visualisations can be applied to create some really informative graphs.

Emoncms MyElectric and SolarPV DashboardsThe emonPi is available in both kit form or as a complete unit. Complete units are housed in a professional looking case sourced from Lincoln Binns. Even if you can’t resist the urge to experiment and order your system in kit form, it is highly recommended that you order the aluminium case to house the finished unit in. Aside from protecting everything inside, the case really gives the unit a polished, professional look.Inside the case you will find a standard Raspberry Pi 2, the GPIO serial connected Arduino measurement shield and an I2C connected 2 x 16-character display.The unit contains built in 433Mhz low power RF which is used for communicating with its external nodes. These nodes can be used to add additional power readings (emonTx) or remote temperature and humidity (emonTH) . Fire up the system with a LAN cable plugged in and the on board display conveniently displays its IP address. Punch that into your favourite browser ( on a PC in the same LAN ) and you get to the login page. Once logged in, you are able to setup the WiFi if you have added an external USB WiFi adapter.The built in 16 x 2 display will also confirm the status of connected devices. In order to measure temperature, an optional DS18B20 temperature sensor needs to be connected. The emonPi can talk to multiple (up to 6) of these sensors as they are individually addressable. Power can be measured using a clip-on CT current sensor and a 9VAC reference supply. You can cheat and omit the 9VAC supply input resulting in the AC voltage being fixed in the software, but then you are not reading true Real Power or Power Factor, so this is not recommended. If measuring solar PV two clip-on CT sensors are required and the 9VAC voltage input is essential as it's required to tell the unit if you generating or consuming power. The second CT can be used to isolate a particular load and see how much that draws. As an example CT 1 could be measuring the total of your house while CT 2 could tell you how much just your water heater or stove uses.Another method to measure power is to use an optical pulse counter sensor that picks up the LED flashes generated by most modern electricity and gas meters.Being able to visualise the power used by your appliances gives a whole new insight into the power needed to run them. The author used the system to evaluate the claims made by the supplier of a hot water boiler control unit that only allows the boiler to heat the water 3 times a day based on your predicted usage. Using the emonPi and Emoncms system it was easy to see exactly how much saving was achieved after installing the control unit. The emonPi is a fantastic piece of kit and well worth having if you would like to contribute towards a greener future.

Weblinks for more information:Home Page – emonPi User Guide - - Shop - User Forum - Blog - Emoncms -

Safety Warning: Interfacing with mains voltages can be potentially lethal. If you are not competent, or not sure of what you are doing rather seek the assistance of a qualified professional.
Categories: Blog

Optical pulse counting with the EmonTH

Wed, 02/09/2015 - 13:53
p { margin-bottom: 0.25cm; line-height: 120%; }

In addition to temperature and humidity sensing the EmonTH has a digital input (with interrupt) that can be used for pulse counting.
This can be used for wired pulse counting or with the Optical LED pulse sensor.
To use the Optical LED Pulse sensor the easiest way is to remove the RJ45 connector and then strip back the black sheathing to reveal the red (3.3V power), black (GND) and blue (pulse) wires.
Connect the red wire to the 3.3V terminal, the black wire to the GND terminal and the blue wire to the terminal labelled D3 (top) or IRQ1/D3 Pulse Counting (bottom of the board).

There are two firmware examples available for the EmonTH for pulse counting, the first is for Pulse counting in addition to DHT22 Temperature + Humidity sensing or DS18B20 temperature sensing:

The second is for pulse counting only if the temperature and humidity sensing is not needed:

To upload these firmware examples you will need the Arduino IDE and libraries installed and a USB to serial programmer to upload the firmware to the EmonTH.

The pulse count is accumulated on the EmonTH until the EmonTH is reset either by an outage or by turning off and on the power.

To record the total accumulated pulse count in emoncms use the wh_accumulator input process which detects resets continuing the total pulse count accumulation from the last value before the reset.
Categories: Blog

3CH WiFi Relay Control Board

Sat, 22/08/2015 - 13:38

We have recently started stocking in the shop a Three Channel WiFi Relay / Thermostat Board designed by our friend Martin Harizanov.
The board has been well designed to physically separate high voltage AC mains from the low voltage logic. The board has an optional power supply to enable the board to be powered directly from 100-240V AC. A wall-mountable plastic enclosure is included. 
The board can be used to control a heating / AC / humidifier via local control loop from on-board sensor. The unit can be programmed with a schedule and or manually controlled via web UI via WIFI. Sensor data and relay status can be posted to Emoncms for logging and graphing. 
NOTE: The board connects to and controls high voltage, knowledge and attention is required when installing to prevent electrical shock.
The relay board is a open software/hardware multi-purpose relay board based on the ESP8266 WiFi SoC. It can control up to three AC or DC loads over the Internet using web UI or MQTT.
  • Powerd direct from 230V AC via isolated on-board PSU (optional extra) or 5V DC via micro USB
  • Built-in web server with mobile device friendly UI and HTTP API to control the relays
  • Thermostat function with weekly scheduling
  • Manual relay control via the UI
  • NTP for network time and scheduling functionality
  • Web server settings, including HTTP port and basic HTTP authentication setup
  • Broadcast relay/sensor data using HTTP GET to services like ThingSpeak or Emoncms
    • Integration with ThingSpeak for charting/analytics visualization
  • Temperature sensor support (one of them, not both at the same time) - (optional extra)
    • DS18B20 one-wire temperature: supports multiple sensors
    • DHT22 (AM2302) Humidity & Temperature
Shop:The relay board can now be purchased direct from our shop: & Set-up: Full technical details and set-up guide are available on Martin's Wiki:
Related Blog Posts:DIY Internet Connected Smart HumidifierWIFI Thermostat with weekly schedulerWiFi IoT 3 channel relay board with MQTT and HTTP API using ESP8266ESP8266 OTA Update 
Overview demo of the board in action by Paul Reed: 

Posting status & sensor readings to Emoncms

Categories: Blog