A Glockenspiel Music Box

My project ‘to-do’ list has for a long time included automating a percussion instrument. I recently decided that a xylophone or glockenspiel type instrument would be a good idea … until I saw the cost of one of those things!

So to fulfill my ambition in an economical way, I downsized to automating a toy glockenspiel. Here’s how it went.

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An RTTTL Parser Class

Ring Tone Text Transfer Language (RTTTL) was developed by Nokia in the 1980’s as a format and mechanism to manage ringtones on cell phones. As Nokia was leader brand at the time, this method was quickly adopted by many other manufacturers and became the de-facto standard for ringtones.

As cell phone hardware became more capable, the use of RTTTL has diminished in favour of more advanced sound production – today most ringtones are simply ordinary sound files. RTTTL files, however, are still useful in may applications.

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Easy Neopixel bitmaps using Excel

Digitally addressable LEDs allow you to control large numbers of LEDs using digital communication to integrated control chips that manage all the rest for you. Matrices of these LEDs can make attractive displays but it can be somewhat of a pain to create bitmaps for display.

I use an Excel worksheet to marshal the data, needing me to just fill in numbers in a worksheet matrix.

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Making noise with a SN76489 Digital Sound Generator – Part 3

In the first part and second part we examined the basics of the SN76489 hardware and the development of a library to manage sound production from this IC.

So, after all this effort, what kind of sound does this hardware produce? In this final post I run a few tests and dig into the resulting waveforms.

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Making noise with a SN76489 Digital Sound Generator – Part 2

In the first part we examined the basics of the SN76489 hardware and how to manage it at the hardware interface between MCU and IC.

To enable sound generation experiments, the first thing I did was create a library to allow me to write sketches without worrying too much about this underlying hardware management.

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Making noise with a SN76489 Digital Sound Generator – Part 1

Most computer games from the 80’s are recognizable by the bleeps and bloops they produced for sound. The easiest way to do this to toggle a single I/O pin to generate a square wave but there are some retro sound ICs that allow us to do much better for a minimal investment.

The SN76489 is one such IC that is still available at a very modest price and is easily interfaced to modern microprocessors.

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Combining Arduino Sketches

Beginners love Arduino coding because there is so much of it available to just copy, load and go without too much thinking required.

Then they find that one thing they want to do is in one sketch and another in a second sketch. All they need to do is combine these sketches! This can be a big hurdle the first time it happens and many fail to get a satisfactorily working product.

There is a systematic approach to this that helps to ensure that things work.

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Finite State Machine Programming Basics – Part 2

The first part of this article introduced a simple Finite State Machine through the exercise of transforming the standard linearly programmed Blink example into a FSM style application.

In this part we’ll look at other common embedded applications and how they can be coded using FSM techniques.

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Finite State Machine Programming Basics – Part 1

Many beginner programmers, once they go beyond the ‘blinking LED’ code, get blocked by not being able to do more than one thing at once. In many cases they are directed to the ‘Blink WithOut Delay’ code (BWOD) as a hint about what to do, but this soon also runs out of steam. BWOD implies, but does not make explicit, a Finite State Machines (FSM) approach.

In this article we’ll evolve the simple linear Blinking LED sketch into a FSM to illustrate the difference in approach.

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Persisting Application Parameters in EEPROM

When an application starts, any data was was part of a previous execution is reset to the initialised values of the variables. Often, however, it is desirable to maintain configuration and state values between processor resets. EEPROM is a good option to store these values.

This article explores ways to make this task easy.

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