Wio Terminal Sensor Fusion - Introduction

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I recently started using a Wio Terminal from Seeed Studio and have found that it is a very capable sensor platform.  Here's a link to their product wiki page: https://wiki.seeedstudio.com/Wio-Terminal-Getting-Started/

I've gotten interested in TinyML after seeing the webinar that Edge Impulse did with Hackster back in April: https://events.hackster.io/tinyml .  Since then I've been looking at boards that have integrated sensors with displays and battery capability that I could use for TinyML.  I found a couple that I like - the Wio Terminal and the Adafruit Edgebadge.  The battery is extra on both units but the cost including the battery is about $40 for either unit.  They have a similar set of sensors and both use a SAMD51 processor but the Wio Terminal had extra features that I wanted (WiFi/BLE, microSD) and it also comes in a case - so I decided to give it a try.

It turns out that the Wio Terminal is only sort of supported by Edge Impulse (the 3 axis accelerometer is supported).  It falls under the category of  "Community Board" but Edge Impulse provides methods of acquiring data and deploying impulses manually so hopefully that will work.  The Adafruit Edgebadge isn't directly supported either.  The Edge Impulse framework should make creating TinyML models easier but worst case I can go though the manual process with Tensorflow-Lite.

Since Project14 is currently running a Sensors design challenge I thought that I'd build a multi-sensor application that also uses an element of TinyML.

Pictorial Overview of Wio Terminal and Battery Pack

Functional layout diagrams of Wio Terminal and Battery Pack

Sensor Fusion Application

I thought that I would create a multi-sensor application that would highlight the Wio Terminal's capabilities.  I had considered using the built-in IR emitter and light sensor but unfortunately since I plan to use the battery pack those sensors won't work because they are designed to use a transparent window on the back of the Wio Terminal and that gets covered by the battery pack.  I wish that they had put those sensors on top near the 3 pushbuttons.  I am going to use a light sensor but I'll need to add that externally via one of the Grove ports.

Feature set

• MS8607 low power digital sensor for pressure, humidity and temperature (external Grove I2C)
• Data display on 2.4" 320x240 LCD display
• Temperature indication using 8 NeoPixel RGB LED stick (external Grove digital)
• Display brightness compensation using TSL2591 digital Light sensor (external Grove I2C)
• Display On/Off voice control using internal analog microphone with TinyML keyword spotting model
• Remote data display over BLE to Android tablet
• Portable operation using 650mA LiPo battery pack
• (Optional) Data logging to SD card if I have time at the end

Parts list

Development steps

I plan to document the application development in a series of blog posts:

• Sensor integration - connection and interface programming
• TinyML keyword spotting using custom model developed with Edge Impulse
• Android application to display sensor data