Driving a 7219 LED matrix from a Raspberry Pi

Flushed with my success in getting data displayed on my cheap LED matrix using a Bus Pirate, I decided that the next step was to see if I could get it working with a Raspberry Pi. Looking around for useful resources to get me started I found: Understanding SPI on the Raspberry Pi from Gordon’s …

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First trial of fourier transform on a KL25z

Progressing with my attempt to record and process ultrasonic sounds, I have spent this evening with a trial version of a fast fourier transform (FFT) on the KL25z ARM board. My hope is that if I can get it running fast enough and well enough, I can offload that part of the work to this …

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Why is it so hard to build Raspberry Pi Linux drivers?

A few days ago I complained a bit about the profusion and confusion around the Linux drivers for the PiBorg LEDBorg multi-colour LED. With a bit of renewed energy, I thought I’d have a go at improving the situation by including a test for board revisionin the driver and ensuring that the correct GPIO pins …

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Basics of a FORTH style systen

I have been reading about the early days of FORTH recently, and learned a lot about the ideas and philosophy behind the language and the system. In the past, when I had tried to create my own FORTH-style languages I think I was missing something important. I had been confusing the “language” of available FORTH …

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Morse code on a big, bright, LEDBorg

I have already proved to myself that I can set up and control the OK LED on the Raspberry PI board from a bare-metal C program, but I didn’t really feel that I entirely understood what was going on. The cop-and-paste code to set up and switch the GPIO line used for the OK LED …

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Building Raspberry Pi code for unit tests

So far, despite working on a variety of bare-metal software features for the Raspberry Pi, I have not managed to achieve my aim of using the principles of TDD (Test-Driven Development). In my “day job” I make a lot of use of TDD techniques, and I am convinced that this approach both greatly improves the …

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What is a “high level language”?

When I was first learning about computer science in the early 1980s, much was made of the difference between “low-level” and “high level” languages. Back then, it seemed as if the distinction was fairly clear: “low level” languages are languages which require you to understand the mechanics of how a computer works, and tell it …

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A real C project

Yesterday I discussed getting ready to do some C work on the Raspberry Pi. Today I’ll go into a bit more of how it went. First I pulled the project source from my git repository using git clone, changed into the project directory and typed make. I had no real expectations what might happen. This …

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Linux, ssh, git and C

Today has been really busy on the Raspberry Pi front. I’ve gone from a little box I’m not sure what to do with, to a fully working Linux development system. Better than that, it’s already helped me find some bugs in an existing piece of software I was working on. Things have moved on a …

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