Of all the many questions that have been asked about issues they face when using the MD_Parola and MD_MAX72xx libraries, there are a few themes that keep re-emerging. In this article I’ll cover the top eight questions, their most likely cause and solution.
A question that I am asked on a regular basis is why particular characters in messages are not displayed ‘as-expected’ by the Parola library. These characters, often typed in from the Serial monitor or embedded within strings, contain non-ASCII characters. Here’s what is happening.
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.
When developing libraries and other complex applications, I find that I often need to exercise specific parts of the library/application as it is being developed.
One way to do this is to write specific test code to exercise functionality. Another is to provide an interactive command line interface to achieve the same.
Until recently I hard coded these testing code CLI for each application. I now have a simple class that enables a flexible and consistent CLI.
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.
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.
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.
Since my previous YX5300 post I have received a number of questions related to how the serial messages between a host and the MP3 module work. Understanding this message flow is important when writing code that uses the MP3 player in an interactive application.
While browsing eBay looking for a module to play extended sound effects (MP3 and WAV files), I came across these modules that looked like they would fit my purpose. The module has been around for a few years and is based on the YX5300 IC. As it turns out they are easy to use and produce a good sound in a small package.
I have for some time wanted to (re)write some of the computer games from my younger days as an exercise in programming and for a bit of fun. I recently decided to do this on a very low-res display made from individual LED matrix modules and in the process created a new library to manage the LED panel display.