Raspberry Pi

A simple and inexpensive shift register can be used to increase the digital output provision of a Raspberry Pi or microcontroller. This well-know technique is easy to apply, but has some limitations that require careful consideration.

Categories: software development, C, embedded computing, Raspberry Pi

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

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

Writing graphical applications for minimal and embedded Linux systems can present a challenge. One of the problems is producing nicely-rendered text without the facilities that a graphical desktop would provide. This article describes how to use the FreeType library to render text to the Linux framebuffer.

Categories: software development, C, Linux, embedded computing, Raspberry Pi

Using the official Raspian repository to assist the construction of a custom Linux for embedded applications is quick and convenient, compared to building everything from source. However, this approach has certain hazards.

Categories: Linux, Raspberry Pi, embedded computing

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

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

Categories: Raspberry Pi, electronics

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

A series of simple, progressive examples that demonstrate the essential features of programming in ARM assembly language.

Categories: Raspberry Pi, software development, embedded computing, assembly

You've created a custom Linux installation for the Raspberry Pi. How do you turn that into a bootable SD card image that can be distributed?

Categories: Linux, 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

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

The HC-SR04 proximity sensor is an inexpensive and widely-used ultrasonic device. Connecting one to an HC-SR04 to a Raspberry Pi is a common educational exercise, but getting accurate, repeatable measurement of distance in a real application is actually quite difficult. This article explains why, and what can be done to improve matters.

Categories: software development, C, embedded computing, Raspberry Pi

Many battery-backed power supplies for the Raspberry Pi, and similar systems, use the INA219 current/voltage monitor IC. This device has an I2C interface by which the Pi can determine the battery voltage and current, and estimate the charge level and run-time. This article describes how to write C code that interacts with the INA219.

Categories: software development, C, embedded computing, Raspberry Pi

In this article I explain how to construct, and program in C, an I²C interface to the popular HD44780 LCD display for the Raspberry Pi. Between the article and the accompanying source code, no technical details are concealed: I present the complete hardware design and every line of C code needed to operate it.

Categories: software development, C, embedded computing, Raspberry Pi

How to construct a custom networked storage (NAS) unit based on a Raspberry Pi and two mirrored USB hard drives -- and why you might want to.

Categories: Raspberry Pi, embedded computing

The Raspberry Pi doesn't offer much in the way of analog outputs, or even hardware controlled PWM. Software-controlled PWM is an alternative in some applications, but it needs to be used carefully, if inefficiencies are to be avoided.

Categories: software development, C, embedded computing, Raspberry Pi

Faster, more of everything, same price -- what's not to like?

Categories: Raspberry Pi

This article is part of a series on building a customer Linux installation for a Raspberry Pi-based appliance. It explains how to install and set up the minimum software to get audio playback working.

Categories: Raspberry Pi, Linux, embedded computing

This article is part of a series on building a custom Linux installation for a Raspberry Pi-based appliance. It explains how to make a bootable SD card with Pi firmware, a Linux kernel, and a shell. It's about as minimal as a Linux system can be.

Categories: Raspberry Pi, Linux, embedded computing

Using high-density vinyl board to construct a practical prototype case without specialist tools or materials

Categories: Raspberry Pi

Using a Raspberry Pi as a media player is by no means a new idea. However, using one as a self-contained hifi component is not common, and requires a bit of work.

Categories: Raspberry Pi, hifi

This article is part of a series on building a customer Linux installation for a Raspberry Pi-based appliance. It explains how to obtain and install fundamental utilities for use in a system with a read-only filesystem, and no package manager.

Categories: Raspberry Pi, Linux, embedded computing

Introducing a series of articles on building a custom Linux installation for the Raspberry Pi, for appliance applications.

Categories: Raspberry Pi, Linux, embedded computing

Peli cases have a reputation of robustness, and look like a promising way to implement a rugged terminal using a Raspberry Pi.

Categories: Raspberry Pi

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

This article is part of a series on building a customer Linux installation for a Raspberry Pi-based appliance. It explains how to set up a system which hitherto only boots to a root shell, to a network-aware installation with service management.

Categories: Raspberry Pi, Linux, embedded computing

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

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

It's entirely possible to run simple, X-based applications in an appliance-based Linux installation: you just have to dispense with the graphical desktop and all its baggage. This article explains how.

Categories: Raspberry Pi, Linux, embedded computing

Many retrocompting projects are designed to be used with a serial terminal. It's easy to emulate a terminal using a desktop workstation, but more authentic to use a dedicated serial terminal. Real VT52-style terminals are expensive, and difficult to transport because they use CRTs. VGA and small HDMI monitors, however, are dirt cheap, as are USB keyboards. This article is about using a Raspberry Pi Zero with a custom Linux to convert a cheap monitor and keyboard into a serial terminal.

Categories: Raspberry Pi, retrocomputing

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

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