Using an I2C analog-to-digital converter chip with the Raspberry Pi, from the ground up

This article is about using an I2C analogue-to-digital device for applications like reading sensor values or monitoring backup batteries. With all the technical bits left in.

Categories: Raspberry Pi, electronics, embedded computing, C

Using an I2C analog-to-digital for temperature measurement on the Raspberry Pi

This article describes how to do simple temperature measurement with a Raspberry Pi, and I2C analog-to-digital converter, and a thermistor.

Categories: Raspberry Pi, electronics, embedded computing, C

Is dithering necessary when reducing the number of bits per sample in an audio waveform?

The use of dithering when mastering a CD is well-established, and its effectiveness is rarely challenged. But is it beneficial in other circumstances when we need to reduce the bit depth of an audio stream?

Categories: hifi, electronics

C devices (and probably shouldn't)

On websites, and in hobbyist kits for Raspberry Pi and Arduino, you'll often see I2C devices connected that have different supply voltages. This is (usually) safe and, in non-critical applications, tends to work. But why?

Categories: Raspberry Pi, electronics, embedded computing, Pico

Why your cheap mains inverter could kill you

A mains inverter is a very useful device, but inexpensive models create significant electrical safety hazards. This article explains why.

Categories: electronics

Making tab-and-slot boxes for electronic prototypes. Or: how I stopped worrying and learned to love the laser

Some thoughts on my first experiments with the design of electronics enclosures for laser cutting.

Categories: Raspberry Pi, electronics

Why switching high currents using a MOSFET and a Raspberry Pi is not as straightforward as it looks

Using a single MOSFET transistor for power switching in microcontroller applications is simple and low-cost, but it often doesn't work as well as expected. Either the switched device doesn't run at full capacity, or the MOSFET gets hot. This article explains why.

Categories: Raspberry Pi, electronics, embedded computing

Some thoughts on always-on OLED displays on smart watches

Why an expensive smart watch is still less good than a cheap Timex, when it comes to telling the time.

Categories: electronics

Handling GPIO-connected switches robustly in C on the Raspberry Pi

It's surprisingly difficult to detect switch actuations in a robust way, dealing with contact bounce and other quirks. This article describes one approach to the problem in C.

Categories: Raspberry Pi, electronics, embedded computing

Converting push-button events to keyboard events in the Raspberry Pi

The Raspberry Pi has a bunch of GPIO pins we can use to connect push-buttons. But how do we interface push-buttons to an application that expects only keyboard input?

Categories: Raspberry Pi, electronics, Linux

Switching a couple of amps with a Raspberry Pi and a relay

Switching loads of an amp or two with a Raspberry Pi or a microcontroller can be accomplished using a small number of inexpensive components. Suitable circuits are widely published, but the details of operation are not always described.

Categories: Raspberry Pi, electronics, embedded computing

Powering a Raspberry Pi from an attached Waveshare USB HAT

Attaching high-capacity hard disks has always been a bit of a problem for the Raspberry Pi. In this article I describe a simple modification to a Waveshare USB HAT, that allows it to power both the attached drives and also the Pi itself.

Categories: Raspberry Pi, electronics

A Raspberry Pi and touchscreen case that anybody can make

This is a design for a robust, wooden enclosure for a Raspberry Pi, battery power supply, and touchscreen, that can be made using hand tools.

Categories: Raspberry Pi, embedded computing, electronics

Making an 8x32 LED auxiliary display with a USB interface, from an LED matrix and a Raspberry Pi pico

A specific application of the Pico7219 library that I described in an earlier article.

Categories: embedded computing, Pico, electronics

Adding a floppy disk controller to my RC2014 Z80 system

No 80s computer is complete without the chucka-chucka-chucka sound of a floppy disk drive doing its thing.

Categories: electronics, Z80, retrocomputing

Designing a dual 5V-to-RS232 serial level converter for the RC2014

Using an RC2014-based retrocomputer with genuine RS232 peripherals requires support for voltage level conversion. Although converter modules are inexpensive and widely available, I wanted to design something that would plug into an RC2014 backplane, just for neatness.

Categories: electronics, Z80, retrocomputing

Some thoughts on a DS1302 real-time clock board for RC2014/Z80 and CP/M

Constructing and programming a real-time clock board for my Z80 CP/M system

Categories: C, electronics, Z80, retrocomputing

Constructing and programming a YM2149 sound board my RC2014 Z80 system

An 80's-style 8-bit computer has to be cable of making 80's 8-bit sound. In this article I describe adding a sound board to my RC2014 system.

Categories: electronics, Z80, retrocomputing

Exchanging files between an SC130 CP/M board and a Linux system

This article describes a couple of methods for sharing data and code between a CP/M system with RomWBW BIOS and a Linux system.

Categories: C, electronics, Z80, retrocomputing

Why RMS watts is a useless measure of power

It's common for hifi amplifiers and speakers to have a power rating expressed in terms of RMS watts. Although RMS amplitude is an important concept in electronic engineering, it's meaningless here, and should be avoided.

Categories: hifi, electronics

Using the Raspberry Pi official 7-inch touch-screen in embedded applications

The official Raspberry Pi 7-inch touchscreen is a useful and well-designed piece of equipment but, if you're using it in a custom (hardware and/or software) build, you'll notice a lack of any relevant technical information. This article tries to supply some of that information.

Categories: Raspberry Pi, electronics, embedded computing

Why does my Raspberry Pi project keep displaying the 'lightning bolt' undervoltage indicator?

The Raspberry Pi is widely used as part of a more complex electronic project or construction. There's a misconception that such a construction can be powered from the same cheap, nasty USB charger that is suitable to power a Pi on its own. Attempting to do this often leads to undervoltage situations. This article explains why, and what constructors can do about it.

Categories: Raspberry Pi, electronics, embedded computing

Why your vintage turntable could kill you

Vintage vinyl records ought, perhaps, to be played on a vintage turntable. Although such appliances are still widely available, and can work well, they fall short of contemporary electrical safety standards.

Categories: electronics, hifi