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Description: The TTS256 is an 8-bit microprocessor programmed with letter-to-sound rules. This built-in algorithm allows for the automatic real-time translation of English ASCII characters into allophone addresses compatible with the Magnevation SpeakJet Speech Synthesizer IC. Combine this with the SpeakJet to build a complete text-to-speech solution.

The TTS256 is offered in a through-hole, 28-pin package. Supplied power should be +5V. Very few connections are required for operation:

Pin# TTS256 Pin# SpeakJet
5 TX (sends serial data to host)
14 Vss (ground)
18 RX (received serial data from host) 15 Buffer Half Full
20 Ready 10 RX
24 SJ_TX
28 Vdd (+5V)

The TTS256 contains over 600 rules for pronouncing English text. While it does a pretty good job of the task, with a less than 5% error rate in most sentences, it will mispronounce some words. Often times, some creative spelling will help.


  • Narrow 28-pin DIP
  • Companion chip to Magnevation SpeakJet and Savage Innovations SpeakGin
  • Built in 600 Rule database
  • 9600bps (8-N-1) serial interface (non-inverted TTL level)
  • Generates speech codes from ASCII text
  • Compatible with Arduino, Basic Stamp, OOPic, Pic, and any processor with serial output


  • Datasheet (note: The correct character to append to the end of text is 0x0D and not 0x0A as listed)
  • Tutorial (Adding the TTS256 to the SparkFun VoiceBox Shield)

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Customer Comments

  • Here is my test video of speakjet + TTS256:
    Now you can add voice and sound effects to your projects!

  • can i change it french language?

  • Does anyone have a schematic showing how to hook up the speakjet to this text to speech chip? Not the voice box shield, but just both through hole parts? Also, I highly doubt it but does anyone know of the .HEX file that can be loaded onto the Cypress PSoC CY8C29466 IC? I have a ton of these chips laying around from an old PSoC 1 project I was doing a few months back.

  • When will this part be back in stock?

  • I found that it was something wrong with macbook serial. With external power or on windows pc it works great!

  • I’ve soldered TS256 to VoiceBox, but using example sketch it can only say 1 letter at once (or 1 symbol like $ or %).
    When I'am trying to type in word or phrase it interrupts after one or two letters. What I’m doing wrong?

  • Nice! Somebody gave my board a free plug here :-) <br />
    <br />
    Thanks neufuture!

  • SpeakJet, TTS256, and Arduino….$76.85
    MP3 Trigger with 1 GB uSD card…$59.90
    (Building a speaking project? PRICELESS…ahem)
    Excluding tax, etc. and how you power things, it’s still quite a difference! Especially true if you simply want “canned” sentences. You may want to save the SpeakJet system for projects which require reporting of data/numbers that can vary.

  • How can I connect this to the voice box shield?

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