Python on Charlie Howlett

Automating Backing Tracks

Sat, 22 Aug 2026 00:00:00 +0000

When rehearsing, alone or with others, I sometimes like to play along to backing tracks with a few of the original instrument parts removed. My hybrid drumming rig works well for this, but preparing the backing tracks can be a pain. Typically, I’d download an MP3 of the song, manually upload it to a stem-separation service, then re-export it in the TM-2’s expected format: stereo 44.1 kHz PCM WAV. This works, but preparing a couple of songs for a rehearsal can take quite a bit of time.

Automating LinkedIn Cross-Posting

Wed, 05 Aug 2026 00:00:00 +0000

I’ve been writing posts here for quite a while, and during that time the site has grown to cover a fairly wide mix of topics. I felt it would be nice to share that work with a larger audience, so I decided to implement a CI/CD pipeline for automatically cross-posting to LinkedIn.

Implementation

I originally considered using Zapier for this, but the free tier did not offer the functionality I needed, so I built a small publishing pipeline myself using GitHub Actions.

Monitoring Devices on My Home Network

Sat, 13 Jun 2026 00:00:00 +0000

My router gives me a basic view of the devices currently connected to my network, but it does not expose historical information. I started this project to fill that gap: a small Raspberry Pi service that scans the LAN, records which devices it sees, and shows that data in a dashboard.

Implementation

The service periodically runs arp-scan to discover devices on the local network, then stores the results in a database with both the current device state and a history of online/offline events. That split lets the system track when a device first appeared, when it was last seen, and how its presence changed across a day or week.

Arduino LoRa Monitoring System

Tue, 11 Jan 2022 00:00:00 +0000

I rent a small drumming practice space that I share with several other musicians on a timetable basis. I built this monitoring system to understand how often people were using their booked time slots and how the room’s environmental conditions changed over time. Since the space has no Wi-Fi and unreliable mains power, the project became an interesting challenge involving low-power hardware, long-range radio communication, and remote data collection.

Sensor node

The sensing node is built around a 3.3V Arduino Pro Mini with sensors for PIR motion, humidity, temperature, and ambient light. Every ten minutes, it wakes up, collects readings, packs them into a small JSON payload, transmits the result by radio, and returns to sleep. I spent a significant amount of time reducing its power consumption so the device could run for roughly six months from three AA batteries. For this project, reliable long-term monitoring mattered more than collecting readings more frequently.

Automating Lights with a Raspberry Pi

Thu, 02 Sep 2021 00:00:00 +0000

Pi Lights was a fairly simple idea and my first exploration into DIY home automation: measure the ambient light level throughout the day using a Raspberry Pi, then switch Wi-Fi lights on or off automatically.

Implementation

The system polls several light-dependent resistors and averages their readings before deciding whether to switch the lights. Using multiple sensors and rate-limiting changes made the automation less sensitive to brief shadows or sudden changes in brightness. A dedicated light-sensing Raspberry Pi HAT would have been more accurate, but I wanted to see if I could build a first pass using components I already had lying around. I ran the software as a Linux service so it would start automatically and continue working in the background without needing any attention.

Raspberry Pi Digital Lock

Fri, 02 Nov 2018 00:00:00 +0000

This first-year group project started with a simple brief: build a keypad-controlled digital lock using a Raspberry Pi. It was a small project, but a very rewarding one, and it introduced me to some great people. Ultimately, our project was chosen by the lecturer to be demonstrated at subsequent university open days.

The main constraint was that we were not allowed to rely on interrupt-driven input for the membrane keypad. Instead, we had to detect key presses by polling the Pi’s pins and working through the keypad matrix ourselves. On top of the basic four-digit passcode entry, we added status LEDs for correct and incorrect codes, a short delay after failed attempts to make brute forcing less practical, and a text-based interface for changing settings after the user had gained access. We also wrote software to attack our own system by generating electrical signals that mimicked key presses.

Decoding a Pen

Tue, 23 Oct 2018 00:00:00 +0000

I recently came across a HMGCC recruitment pen with a curious message printed along the side. It seemed to be a small hexadecimal puzzle, which piqued my curiosity enough to see if I could decode it.

After manually transcribing the hexadecimal values from the pen, I first played around in CyberChef to get a feel for how the message might be encoded. Once I had a likely approach, I wrote a short Python script to put the decoding steps somewhere concrete: