Author Archives: Helen Lynn

Open source energy monitoring using Raspberry Pi

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OpenEnergyMonitor, who make open-source tools for energy monitoring, have been using Raspberry Pi since we launched in 2012. Like Raspberry Pi, they manufacture their hardware in Wales and send it to people all over the world. We invited co-founder Glyn Hudson to tell us why they do what they do, and how Raspberry Pi helps.

Hi, I’m Glyn from OpenEnergyMonitor. The OpenEnergyMonitor project was founded out of a desire for open-source tools to help people understand and relate to their use of energy, their energy systems, and the challenge of sustainable energy.

Photo: an emonPi energy monitoring unit in an aluminium case with an aerial and an LCD display, a mobile phone showing daily energy use as a histogram, and a bunch of daffodils in a glass bottle

The next 20 years will see a revolution in our energy systems, as we switch away from fossil fuels towards a zero-carbon energy supply.

By using energy monitoring, modelling, and assessment tools, we can take an informed approach to determine the best energy-saving measures to apply. We can then check to ensure solutions achieve their expected performance over time.

We started the OpenEnergyMonitor project in 2009, and the first versions of our energy monitoring system used an Arduino with Ethernet Shield, and later a Nanode RF with an embedded Ethernet controller. These early versions were limited by a very basic TCP/IP stack; running any sort of web application locally was totally out of the question!

I can remember my excitement at getting hold of the very first version of the Raspberry Pi in early 2012. Within a few hours of tearing open the padded envelope, we had Emoncms (our open-source web logging, graphing, and visualisation application) up and running locally on the Raspberry Pi. The Pi quickly became our web-connected base station of choice (emonBase). The following year, 2013, we launched the RFM12Pi receiver board (now updated to RFM69Pi). This allowed the Raspberry Pi to receive data via low-power RF 433Mhz from our emonTx energy monitoring unit, and later from our emonTH remote temperature and humidity monitoring node.

Diagram: communication between OpenEnergyMonitor monitoring units, base station and web interface

In 2015 we went all-in with Raspberry Pi when we launched the emonPi, an all-in-one Raspberry Pi energy monitoring unit, via Kickstarter. Thanks to the hard work of the Raspberry Pi Foundation, the emonPi has enjoyed several upgrades: extra processing power from the Raspberry Pi 2, then even more power and integrated wireless LAN thanks to the Raspberry Pi 3. With all this extra processing power, we have been able to build an open software stack including Emoncms, MQTT, Node-RED, and openHAB, allowing the emonPi to function as a powerful home automation hub.

Screenshot: Emoncms Apps interface to emonPi home automation hub, with histogram of daily electricity use

Emoncms Apps interface to emonPi home automation hub

Inspired by the Raspberry Pi Foundation, we manufacture and assemble our hardware in Wales, UK, and ship worldwide via our online store.

All of our work is fully open source. We believe this is a better way of doing things: we can learn from and build upon each other’s work, creating better solutions to the challenges we face. Using Raspberry Pi has allowed us to draw on the expertise and work of many other projects. With lots of help from our fantastic community, we have built an online learning resource section of our website to help others get started: it covers things like basic AC power theory, Arduino, and the bigger picture of sustainable energy.

To learn more about OpenEnergyMonitor systems, take a look at our Getting Started User Guide. We hope you’ll join our community.

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A live-streaming Raspberry Pi nest cam: your essential Easter Monday viewing

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It’s Easter Monday, a public holiday here in the UK, and Pi Towers is still and silent. Even the continuous flight augering piler on the massive building site next door is, for a time, quiet. So here is the briefest of posts, to share with you a Raspberry Pi cam live-streaming from a blue tit nest in Alan McCullagh‘s parents’ garden in Kilkenny, Ireland. You’ll need to have Flash installed to watch.


BirdBoxKK1 @ USTREAM: . Birds

The eggs are expected to hatch 14 days after the last laid egg, and the mother was still laying on Thursday, so check in towards the end of the month to catch a first glimpse of the chicks. Alan’s set-up is based on our Infrared Bird Box learning resource; tell us in the comments if you’ve made something similar, or if you plan to.

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An affordable ocular fundus camera

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The ocular fundus is the interior surface of the eye, and an ophthalmologist can learn a lot about a patient’s health by examining it. However, there’s a problem: an ocular fundus camera can’t capture a useful image unless the eye is brightly lit, but this makes the pupil constrict, obstructing the camera’s view. Ophthalmologists use pupil-dilating eye drops to block the eye’s response to light, but these are uncomfortable and can cause blurred vision for several hours. Now, researchers at the University of Illinois at Chicago have built a Raspberry Pi-based fundus camera that can take photos of the retina without the need for eye drops.

Dr Bailey Shen and co-author Dr Shizuo Mukai made their camera with a Raspberry Pi 2 and a Pi NoIR Camera Module, a version of the Camera Module that does not have an infrared filter. They used a small LCD touchscreen display and a lithium battery, holding the ensemble together with tape and rubber bands. They also connected a button and a dual infrared/white light LED to the Raspberry Pi’s GPIO pins.

When the Raspberry Pi boots, a Python script turns on the infrared illumination from the LED and displays the camera view on the screen. The iris does not respond to infrared light, so in a darkened room the operator is able to position the camera and a separate condensing lens to produce a clear image of the patient’s fundus. When they’re satisfied with the image, the operator presses the button. This turns off the infrared light, produces a flash of white light, and captures a colour image of the fundus before the iris can respond and constrict the pupil.

This isn’t the first ocular fundus camera to use infrared/white light to focus and obtain images without eye drops, but it is less bulky and distinctly cheaper than existing equipment, which can cost thousands of dollars. The total cost of all the parts is $185, and all but one are available as off-the-shelf components. The exception is the dual infrared/white light LED, a prototype which the researchers explain is a critical part of the equipment. Using an infrared LED and a white LED side by side doesn’t yield consistent results. We’d be glad to see the LED available on the market, both to support this particular application, and because we bet there are plenty of other builds that could use one!

Read more in Science Daily, in an article exploring the background to the project. The article is based on the researchers’ recent paper, presenting the Raspberry Pi ocular fundus camera in the Journal of Ophthalmology. The journal is an open access publication, so if you think this build is as interesting as I do, I encourage you to read the researchers’ presentation of their work, its possibilities and its limitations. They also provide step-by-step instructions and a parts list to help others to replicate and build on their work.

It’s beyond brilliant to see researchers and engineers using the Raspberry Pi to make medical and scientific work cheaper and more accessible. Please tell us about your favourite applications, or the applications you’d develop in your fantasy lab or clinic, in the comments.

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International Women’s Day: Girls at Code Club

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On International Women’s Day and every day, Raspberry Pi and Code Club are determined to support girls and women to fulfil their potential in the field of computing.

Code Club provides computing opportunities for kids aged nine to eleven within their local communities, and 40 percent of the children attending our 5000-plus UK clubs are girls. Code Club aims to inspire them to get excited about computer science and digital making, and to help them develop the skills and knowledge to succeed.

Big Birthday Bash Code Club Raspberry Pi Bag

Code Club’s broad appeal

From the very beginning, Code Club was designed to appeal equally to girls and boys. Co-founder Clare Sutcliffe describes how she took care to avoid anything that evoked gendered stereotypes:

When I was first designing Code Club – its brand, tone of voice and content – it was all with a gender-neutral feel firmly in mind. Anything that felt too gendered was ditched.

The resources that children use are selected to have broad appeal, engaging a wide range of interests. Code Club’s hosts and volunteers provide an environment that is welcoming and supportive.

Two girls coding at Code Club

A crucial challenge for the future is to sustain an interest in computing in girls as they enter their teenage years. As in other areas of science, technology, engineering and maths; early success for girls doesn’t yet feed through into pursuing higher qualifications or entering related careers in large numbers. What can we all do to make sure that interested and talented young women know that this exciting field is for them?

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Astro Pi: Goodnight, Mr Tim

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On Saturday, British ESA astronaut Tim Peake returned to Earth after six months on the International Space Station. During his time in orbit, he did a huge amount of work to share the excitement of his trip with young people and support education across the curriculum: as part of this, he used our two Astro Pi computers, Izzy and Ed, to run UK school students’ code and play their music in space. But what lies ahead for the pair now Tim’s mission, Principia, is complete?

Watch Part 4 of the Story of Astro Pi!

The Story of Astro Pi – Part 4: Goodnight, Mr Tim

As British ESA astronaut Tim Peake’s mission comes to an end, what will become of Ed and Izzy, our courageous Astro Pis? Find out more at Narration by Fran Scott:

Ed and Izzy will remain on the International Space Station until 2022, and they have exciting work ahead of them. Keep an eye on this blog and on our official magazine, The MagPi, for news!

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Astro Pi: In Space, No One Can Hear You Code

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British ESA astronaut Tim Peake has been on board the International Space Station with our Astro Pi units, Izzy and Ed, for exactly six months today. As Tim prepares to return to Earth this Saturday, we bring you the third part of their animated adventures: when our two spacefaring Raspberry Pi computers run into a problem even their hero Robonaut can’t fix, who can help them?

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During his time in space, Tim has been using Ed and Izzy to run apps, carry out science experiments and play music designed and coded by UK school students, and he’s taken some great photos of them on the station:


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Both computers have also spent some weeks in a flight recorder mode, saving sensor readings to a database every ten seconds, and we’ve made these space data available to everyone to download and analyse. Take a look at our Flight Data Analysis resource to explore what they recorded as they orbited our planet.

Ed and Izzy will say goodbye to Tim when he returns from space this Saturday; you’ll be able to watch him land. Our Astro Pi units will stay on board the ISS until 2022, and we hope we’ll soon be able to share exciting news about what they’ll be doing next. Stay tuned!

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