C/C++ on Charlie Howlett

Jar Light Display

Tue, 28 Jul 2026 00:00:00 +0000

Almost every night I light a candle before going to bed as part of my nighttime routine, so I have heaps of leftover glass jars that seem too nice to throw away. Last weekend my girlfriend and I had the idea to turn one into a nice-looking enclosure for an interactive LED light project.

The first step was cleaning out the old wax and wick.

Next, we made a display that exactly fits the unique shape of the jar. We bought a strip of individually addressable LEDs, cut it into shorter sections, and wired them together into a flexible circular matrix.

Building an Arduino Robot Car in a Day

Wed, 12 Jun 2024 00:00:00 +0000

I set myself a small challenge: build a working Arduino robot car in a single day, using only electronics parts I already had around the flat.

I decided to build it because I had found a TB6612FNG motor driver lying around, along with an Arduino Mini, a battery pack, and a couple of small wheels with DC motors. For the body, I used a little wooden board I had spare and fixed the motors and other parts to it with some metal joinery pieces.

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.

Llama Bot

Sat, 01 Jan 2022 00:00:00 +0000

This project started with a burst stress toy llama that seemed too good to throw away. I decided to give it a second life as a singing, dancing robot, which turned a cute toy into a compact embedded engineering project involving electronics, power, motion, and control logic.

Implementation

The electronics were built around an Adafruit Feather HUZZAH ESP8266, with a servo for movement, a buzzer for playing songs, and a rechargeable LiPo battery connected to the board’s micro-USB charging port. I also added an on/off switch by grounding the ESP8266 enable pin, allowing the toy to draw effectively no current while switched off instead of slowly draining the battery. Inside the llama, a structure made from cardboard, copper wire, and hot glue held the components in place and made the damaged toy sturdy enough to survive repeated movement.

Anti-Lock Braking System

Sun, 17 Mar 2019 00:00:00 +0000

Overview

My final year at university was primarily focused on my dissertation, for which I chose to implement and evaluate an anti-lock braking system. The idea was suggested to me by a professor who noted that an accurate, open-source ABS model would aid his research. To achieve this, I based the ABS control loop on a Bosch algorithm described in engineering literature and ran simulations using the open-source software “Speed Dreams 2”, which features advanced vehicle physics.