Here’s an Arduino-compatible GI-SP0256-AL2 speech synthesizer module that I’m finishing up. It’s a great 1980’s-era allophone speech synthesizer chip that was used in Intellivision expansion modules and sold at RadioShack stores for years for about $12. You can still find them from time to time on ebay, and they produce a fantastic synthesized speech sound. The chip is sometimes called the “SPO256-AL2” (with the letter “O” as opposed to the numeral “0”) due to a typo in the original documentation from RadioShack.

First, here’s a video of the speech synthesizer in action:

The chip works by sending it a series of allophones (59 to choose from) that make up all the sounds of the English language. It’s a real rats nest when wired up on a breadboard, so I thought I’d throw it together on a little 5cm circuit board. (Let me know by commenting below if you’re interested in one.)

The board leaves open (and accessible) four analog pins and four digital pins (two with PWM), plus two additional analog pins in you use the serial clock and data lines that are set up for I2C communication by default. The eight non-I2C pins are paired with ground pins, and three are set up by default to configure the device address for I2C communication. It requires regulated 5V via a standard 6-pin FTDI connection (you don’t need to use all pins unless you’re programming it), and there’s an output jumper at the bottom that can be amplified to power a speaker.

Here’s the design. It’s about 2 inches square. I’ll post the code when I get it finished up. Let me know if you’re interested!

Arduino-compatible SP0256-AL2 Speech Synthesizer

Some Code

Here’s some of the code I used for my test. I’ve updated the code on Februay 18, 2012 to include the required loop() method (which I’d accidentally left out) and to rename the “SS” constant so it doesn’t conflict with the Slave Select constant in case that’s defined.

Allophones

Here are the allophone definitions: