Adpcm2hex software.

It is actually possible to use a 8 bit PIC's to reproduce sound but the road is quite long and a bit bumpy.
First of all you will of course need one or more wave soundfiles, not to long though as the files are stored in the PIC's program memory, then you will have to process the sound file(s) with a sound editor eg. GoldWave - trim sound start and stop points, raise volume to max and downsample to the appropriate format, encode to 4bit Adpcm with WinSpeech from Microchip application note AN643 and use my brothers Adpcm2hex software to generate a Basic include file or a C file for eeprom storage (experimental). Take a look in the pdf file below for our recipe.
Download the source code for our helloworld sound file example and try for yourself. We use a R2R resistor network as DAC and an active opamp forth order filter to filter the sound, we will reveal this later.
Below you can see some pictures of the software my brother has made to make an include .bas file for a basic compiler or a hex file for an eeprom to use with an C compiler (click on the picture to enlarge it):

This is how we generate an adpcm file for a 8 bit PIC to reproduce sound.
We use GoldWave to process the soundfile, helloworld in this example.
We use WinSpeech from Microchip Application note AN643 to generate the adpcm file for my brothers software.
This is helloworld played by a 18F452 and recorded on a PC and encoded in 128Kb mp3 format.
Adpcm2hex startup splashscreen. Update! The program has been updated with a init sound.		Adpcm2hex 2.50 2010.04.09
Basic (.bas file) include file option choosen (MCU = Micro Controller Unit), with the adpcm soundfile helloworld loaded. Update! The program has been updated with a init sound.		Helloworld source code example 2010.04.09
The processed include .bas file.
C eeprom file option choosen, with the adpcm soundfile helloworld loaded. You can choose between different eeproms with the radio buttons on the right and the progress bar at yhe bottom shows how much space your soundfile(s) are using.
The processed C include file with sound data start and stop points.
The processed eeprom hex file, ready to be burned in an eeprom.

This page was last updated 2010-04-21.