Got it working...

A project log for 1979 "Heathkit" D&D Digital Dice Tower

Revision 2 of the resto-Mod Dungeons and Dragons Digital Dice Tower based on a 1975 Bell & Howell IMD-202 Digital Multi-meter

John AndersonJohn Anderson 02/10/2020 at 05:423 Comments

I got sound/voice working after some very interesting experimentation. This version of the dice tower uses a ATmega328. So I had to pack all the logic and audio samples into 32K of flash. It will tell the user the dice count, die type, and the die roll result. It took some compression tricks to get the all the samples packed in there. I'll explain it all in another log if someone is interested. However, seeing this project has just one like and no followers, I won't bother posting the details until someone asks about it.

For now, here's a video demonstrating this latest version of the Heathkit D&D Digital Dice Tower.


John Anderson wrote 02/10/2020 at 22:49 point

I just looked through the header file that my Linux command line tool generates and realized that I am getting over 50% of lossy compression of the audio stored. I have 8.12 secs of 8-bit mono audio that is sampled and played back at 7812 Hz. That's enough to store the 30 words/letters required for the dice tower's vocabulary. 

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John Anderson wrote 02/10/2020 at 16:15 point

I like the challenge of doing more with less and doing it from scratch. That's why I like to use homebuilt AVR microcontroller boards (not Raspberry PI) and no Arduino libraries. It forces me to understand more about what I am playing with. In this case, I had to develop an audio compression scheme that reduced the size of my audio samples by about 30%-40% and could easily run on the little AVR at 8 mHz. That was fun :-)

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Ken Yap wrote 02/10/2020 at 07:57 point

One possibility for future builds is to outsource the audio playback to a MP3 player like this:

Clones are available from any number of eBay sellers for about $1. Then add a TF card.

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