Offline speech recognition MCU module comes with speaker, microphone, and UART connectors

We found out about Unisound US516P6 RISC microcontroller inside an offline voice assistant module last May. The module offers offline speech recognition for just $2 to $4, with good performance, and excellent privacy since no cloud service nor Internet connection is needed.

That module requires some soldering, but if you’d prefer something easier to connect the “SU-10A” offline speech recognition MCU module comes with connectors for a speaker, a microphone, as well as UART connectivity to a host MCU if needed.

“SU-10A” module specifications:

MCU – Unisound US516P6 RISC microcontroller @ 240 MHz with FPU, DSP instruction, FFT accelerator, 242KB SRAM, 2MB flash
Audio
- Built-in 3W mono Class AB power amplifier.
- 2mm pitch connector for speaker (4 Ohms up to 2.9W, 8 Ohms up to 1.8W)
- 2mm pitch connector for electret microphone
Debugging/programming – UART port for serial console (5V or 3.3V supported)
Host interface – 2mm pitch 4-pin connector for UART (Tx/Rx) to host MCU
Power Supply – 3.6 to 5.5V / 200mAvia 4-pin “Host Interface” connector
Average power consumption – 60mA @ 5 V
Dimensions – 33 x 28 x 9 mm
Temperature Range – 20°C – 85°C
Humidity – 5% – 95% RH

Sadly the module does not expose any of the GPIO from the Unisound microcontroller, at least not through headers or connectors, and eight GPIOs appear to be available under the board.

The module is suitable for smart appliances, toys, lights, and devices that require voice control without a network connection. I found the module ICStation where it is sold for $5.03.

But as usual, ICStation is just awful when it comes to documentation and resources for their board, as there isn’t just any. As we mentioned in our previous article about US516P6 MCU, programming is done through Blockly visual programming IDE and should require a hardware programmer. I’ll probably understand how it all works next month, as Wireless Tag/AI Thinker plans to send me a US516P6 module together with some ESP32-C3 boards. Here’s a short demo in the meantime.

Jean-Luc Aufranc (CNXSoft)

Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.