speech synth

2 Articles

Speech Synthesis On A 10 Cent Microcontroller

October 31, 2025 by 62 Comments

Speech synthesis has been around since roughly the middle of the 20th century. Once upon a time, it took remarkably advanced hardware just to even choke out a few words. But as [atomic14] shows with this project, these days it only takes some open source software and 10-cent microcontroller

The speech synth is implemented on a CH32V003 microcontroller, known for its remarkably low unit cost when ordered in quantity. It’s a speedy little RISC-V chip running at 48 MHz, albeit with the limitation of just 16 KB of Flash and 2 KB of SRAM on board.

The microcontroller is hooked up to a speaker via a simple single-transistor circuit, which allows for audio output. [atomic14] first demonstrates this by having the chip play back six seconds of low quality audio with some nifty space-saving techniques to squeeze it into the limited flash available. Then, [atomic14] shows how he implemented the Talkie library on the chip, which is a softwarehttps://www.youtube.com/watch?v=RZvX95aXSdM implementation of Texas Instruments’ LPC speech synthesis architecture—which you probably know from the famous Speak & Spell toys. It’s got a ton of built in vocabulary out of the box, and you can even encode your own words with some freely available tools.

We’ve seen [atomic14] tinker with these chips before, too.

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2022 Hackaday Prize: Talking Clock Built With Old-School Gear

August 16, 2022 by 2 Comments

Any smartphone or laptop could be a talking clock if you wished it so. However, we think this build from [Marek Więcek] is more fun, which uses discrete vintage chips to get the job done the old fashioned way.

The work started when [Marek] was tinkering with a 65C02 CPU, giving it an EPROM, some RAM, and some logic ICs to create something akin to a modern microcontroller in functionality. It came to be known as the 6502 Retro Controller Board. Slowly, the project was expanded with various additional modules, in much the same way one might add shields to an Arduino.

In this case, [Marek] expanded the 6502-powered board with a series of 7-segment displays, along with an RTC to keep accurate time. A classic SP0256-AL2 speech synthesis chip was then added, allowing the system to not only show the time, but read it aloud, too. As a bonus, not only can it tell you the hour, minute, day, and date, but it will also read various science-fiction quotes on demand.

Like most 80s speech synths, the output is robotic and a little difficult to parse. However, that’s part of the charm that makes it different compared to the speaking virtual assistants of today.

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