Posts

SAMD21E18 PCB

In follow up to my mysensors.org build, I’ve always wanted to design PCB and try my hand at SMD soldering. I normally use veroboard on a 0.1" pitch but the time to cut and solder wires makes for a slow build.

MySensors

It gets warm and humid here in the summer and feels too dry in the winter. To measure this I built up two MySensors Sensebender Micro boards and designed a 3D printed a case to go with them:

Adventures in making PCBs

As part of adding MySensors based sensors around the house, I want to make an integrated version of the Sensebender Micro upgraded with a SAMD21 and a RFM69HCW radio. I’ve never had much success with making PCBs at home, so I thought I’d give it another try and record the experiments.

juju.net.nz/michaelh on IPFS

The short story is that this blog is now available on IPFS at https://juju.net.nz/ipns/juju.net.nz/michaelh/ and https://gateway.ipfs.io/ipns/juju.net.nz/michaelh/ This is done by generating the blog a second time with ipfs/ as the basepath, changing to relative links, and then adding and updating the name as part of the buildbot script.

Raspberry Pi Zero boot speed

I enjoy working on embedded systems, but there’s a significant amount of work you have to do in getting the platform ready before getting to the more interesting business logic. The Raspberry Pi Zero W solves most of these problems: it’s small, has decent I/O, a decent price ($10 + $6 for storage + $4 for shipping) and runs full Linux so I can use my current language of choice.

cxx17: working through Cracking the Coding Interview

I’m working my way through Cracking the Coding Interview as a way of learning the new features and tool ecosystem of C++17. Q1.9 reminded me of those games where you need to make a shape by drawing straight lines through dots.

go packages on your own domain

go get has a nice feature where it will fetch the package URL and, based on a meta tag, redirect to the actual location. Here’s the nginx config I use to redirect go get juju.

DFRobot FIT0441 pinout

I ordered two FIT0441 brushless motors for use in v2 of my balancing robot. The DFRobot wiki page on the motor is incorrect so I thought I’d blog about it so someone else can find it 🙂

ESP8266 IO bridge

github.com/eriksl/esp8266-universal-io-bridge looks cool – it exposes the I/O of a ESP8266 wifi module including the GPIO, I2C, PWM, ADC, and UART via a line based telnet interface.

A toy PL/0 compiler

I’ve released a toy compiler for the PL/0 educational language at https://juju.net.nz/src/cgit.cgi/pl0.git/ or https://github.com/nzmichaelh/pl0. I did this as, despite working with compilers for a fair part of my life, I’d never written one from scratch.