Arduino on Codewrite Dev Doc

Home Assistant UPS Mk II

Sun, 27 Sep 2026 00:00:00 +0000

I decided to have an uninterruptible power supply (UPS) for my Home Assistant (running on a Raspberry Pi). The design I came up with is shown below:

The input from the mains is supplied by a 15V AC to DC adapter (wall wart). This is shown as Vcc/Vss on the diagram above. There are two DC to DC converters, one that powers the Raspberry Pi and one that powers an Arduino Nano. The rPi converter is a LM2596 and the Nano converter is a smaller device (which says it can deliver 3A but it only needs to deliver about 20mA).

Debugging ESP32 S3 in VS Code

Sat, 19 Sep 2026 00:00:00 +0000

Debugging is much better than littering your code with print statements for lots of reasons - which I’m not going to go into here. But setting debugging up is not always straightforward.

To make things easier, I use an esp32 s3 board that had JTAG built into it. I found this article on the internet and loosely followed the instructions: How to use JTAG built-in debugger of the ESP32-S3 in PLATFORMIO.

Home Assistant Serial Link to an Arduino

Fri, 27 Feb 2026 00:00:00 +0000

The purpose of this project was to connect an Arduino Nano to the USB port that Home Assistant was running on. For me that is a Raspberry Pi 4 but this solution should work with any Home Assistant hardware. And the reason for using a serial connection over USB (rather than wirelessly with WiFi or similar) could be for many reasons:

Wifi may not be available (e.g. if the network is down)
It is more secure
It is un-jammable

The ultimate plan for me was to create an uninterruptable power supply for Home Assistant from bits that I had:

Arduino Low Power Encryption

Wed, 19 Aug 2020 00:00:00 +0000

This was my experiment in creating a low power Arduino that can communicate wirelessly to a Raspberry Pi using an HC-12. By low power I mean run for a couple of years on a 18650 battery. Encryption should be unhackable by today’s standards.

I did a presentation for the Raspberry Pint group, the video is here.

The code is on my Github repo. I had to do some mods to the Arduino board to make it low power (removing the regulator and power LED resistor):

Arduino Default Libraries

Fri, 14 Aug 2020 00:00:00 +0000

I used to think that the default libraries in the Arduino IDE would be the best available but having come across a couple of cases where this isn’t true I would definitely search for better lib libraries now…

What libraries?#

What am I talking about? Well the two that have better alternatives are:

Keyboard#

The reason why this didn’t work for me was because the BIOS on my desktop PC didn’t recognize the Arduino Leonardo as a keyboard. So I tried [the HID project][HID-Project] - which works flawlessly.

Generating sounds on the Arduino

Thu, 13 Aug 2020 00:00:00 +0000

This is a small project to read wav files from a micro SD card via an Arduino Nano and then play them directly to a loudspeaker. I’ll state upfront that this isn’t the easiest way to do this (there are MP3 modules and libraries), but I wanted to:

Understand sound generation using a microcontroller from first principles
Have some tools / ideas about how to generate sounds for any future projects

As an idea of the sort of thing I was thinking of - I’ve been thinking of a DIY “ring” doorbell. I already have a camera that can see anyone approaching the front door. A 433.92MHz receiver could detect when the doorbell is pressed (so no new doorbell required). A Raspberry Pi (i.e. the one with the camera) controlling it all and sending and receiving to my mobile phone. A lot more work than just buying a Ring doorbell - but a lot more satisfying!