Lolin ePaper shield for esp8266
Posted on July 9, 2020
| Barnaby Gray
Just picked up one of these neat ePaper displays from AliExpress for $9.90 for the esp8266. It’s 2.13" in diagonal, has a resolution of 250x122 and is made by Lolin.
Lolin produce a whole bunch of quality esp8266 items - including the ubiquitous Wemos D1 Mini and various I2C sensors. It’s not a shield in that you can sit it on top of an ESP - you need a couple of cables to use the lcd with the esp, you’ll want to get the TFT I2C Connector Shield ($0.
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Making a washing machine smart
Posted on February 9, 2018
| Barnaby Gray
A minor annoyance, but one that plagues me: when you put a wash on, forget about it finishing, only to discover the damp washing hours later festering in the washing machine. There’s only one thing to it - a massively overengineered smart home solution!
Sonoff POW This is a smart device that can be had from Chinese online retailers for ~$9 - bargain. In it there’s a wifi microcontroller, the venerable ESP8266, a mains relay and a current/voltage sensor to measure power usage.
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Baking with sympy
Posted on June 2, 2017
| Barnaby Gray
Problem: a recipe calls for 250ml double cream (48% fat) and 100ml whole milk (3.5% fat). I only have double cream (48% fat) and semi-skimmed milk (1.5% fat).
How much do I adjust the double cream by to get the same quantity liquid and fat content?
It’s a simple simultaneous equation, so solving it with Sympy is overkill, but developers do overkill best, right?
So:
>>> linsolve([Eq(x + y, 350), Eq(x*.
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Kibana baby kick counter - part 2
Posted on May 15, 2017
| Barnaby Gray
This is part 2 of 2 about using Elasticsearch and Kibana to track patterns in baby activity. Part 1 here covers the hardware and setup for tracking baby kicks.
Machine learning Having collected about 6 weeks of baby kicking data, it’s time to test the new toy in the Elasticsearch stack: Machine learning.
Installing this was a straightforward case of following the instructions, and from the ‘Machine Learning’ new menu item in Kibana, I chose ‘Create new job’, and ‘Create a single metric job’:
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Kibana baby kick counter
Posted on April 29, 2017
| Barnaby Gray
This is part 1 of 2 about using Elasticsearch and Kibana to track patterns in baby activity.
Part 2 is here.
Kicking things off According to countthekicks.org “Counting baby kicks is important because changes in your baby’s movement pattern may indicate potential problems with your pregnancy”. Counting and patterns sounds like a technological problem for Elasticsearch and Kibana!
There’s a few apps dedicated to tracking kicks (over 20 apps last count on Android), but they’re mostly crap (lacking detailed history or useful insights) and being a data geek I’m not entirely happy handing over the data without a definite means to export it.
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Pairing Yale Conexis Lock and Openzwave
Posted on April 19, 2017
| Barnaby Gray
I struggled getting the Yale Conexis smart lock working with the Aeotec Z-Stick Gen5. Turns out the issue is it must be a secure pairing - the default method in the instructions (unplug Z-Stick, press button near to the device, initiate pairing), does not perform a secure pairing, and so even though the device will appear in software, you won’t get any state for it or be able to perform an actions.
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Raspberry Pi Zero W and Mi Flora plant monitor
Posted on March 19, 2017
| Barnaby Gray
The new Raspberry Pi Zero W is the perfect pairing to go with the Xiaomi Mi Flora. The Flora is a bluetooth stick you push into the soil next to a plant and can be polled over Bluetooth LE for the sensor data - soil moisture, temperature, light and soil conductivity.
Part list Raspberry Pi Zero W. I used Pimoroni (£9.60 + £2.50 postage) as they’re great and ship fast. You shouldn’t need the Adapters kit if you’ve the necessary adapters already, or you might get away with setting up the Pi headless without them anyway.
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Bluetooth on Archlinux on the Pi Zero W
Posted on March 18, 2017
| Barnaby Gray
Bluetooth doesn’t work out the box for Archlinux but thankfully a helpful user has created packages to support the Pi 3 which also work on the Zero W (see forum post). There’s a couple of caveats to getting them working I’ll step through.
First install bluez and bluez-utils older than 5.44 - you must get them from an archive. The reason being hcitool is required and it’s been dropped from bluez 5.
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Garage security system
Posted on February 26, 2017
| Barnaby Gray
This project was to build a simple garage security system to alert of intruder access to the garage by notification over Wifi.
Parts list Wemos D1 mini & mini protoboard The esp8266 is the workhorse of any project - it monitors the sensors and sends notifications over Wifi. I used the Arduino system with Platformio for development.
For the small amount of circuitry required one of these tiny protoboards:
![D1 mini protoboard](/images/mini protoboard.
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Amazon Dash doorbell
Posted on December 14, 2016
| Barnaby Gray
The Amazon Dash is a Wifi button originally intended for the ultra- lazy for reordering consumables from Amazon when you’re running low. It was going to £1 recently in Black Friday promotions, so I thought I’d have to snap one up. Normally they go for a not bank breaking £5, which you can recoup if you actually want to order one of the items once on them.
When pressed it connects through Wifi to send a request to Amazon, then turns off - looks fit for repurposing for home automation!
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