Fullscreen HTML5Med Res (??MB)HTML4

Wearable ESP32 and the Sparkle Stitch Kit Electronic “wearables” have been around for a while, but we haven’t gotten into them until now. Not only can these particular electronic products be attached to clothing (or even made part of it!), but they can also connect to WiFi networks. So you could even design clothing that lights up and adapts to your location, or is controlled by your smartphone! W earable electronics is a growing field, mainly due to the popularity of the Arduino system, which was one of the early adopters of wearable electronics. People whose main interest is clothes and accessories might not have a strong electronics background. As Arduino is aimed at ‘creative’ people rather than ‘technical’ people, it’s a good match. One of the earlier variants of Arduino wearables was dubbed the Lilypad. The distinguishing feature of many of these boards is a round shape and several large pads around the edges for making connections (hence the name Lilypad). In fact, in addition to the items we’re reviewing in this article, Jaycar also stocks the Duinotech Lilypad Plus (Cat XC3920). This is a variant on the original Lilypad design that uses the ATmega32u4 microcontroller (making it like the Leonardo). The large pads allow wires to be easily attached via alligator clips or even by tying conductive thread through the holes. A complement of small add-on boards in the vein of Arduino modules is also available. Review by Tim Blythman & Nicholas Vinen 104 Silicon Chip Australia’s electronics magazine siliconchip.com.au The Duinotech Wearable ESP32 Development Board from Jaycar (XC3810) is a compact but powerful processor ideal for creating wearable electronics. We recently had the opportunity to try out Jaycar’s new Duinotech Wearable ESP32 Development Board (Cat XC3810). It’s a disc-shaped PCB 56mm across with eight large Lilypad-style pads as well as two rows of nine standard 2.54mm header pads. The eight larger pads break out connections to the battery positive, USB positive, 3.3V rail and ground as well as GPIOs 12, 14, 27 and 33. A modest number of components cover the thin (0.6mm) board. The largest part is the ESP32-WROOM-32 module, which contains a 4MB flash memory IC as well as the microcontroller and WiFi chipset. A CH340G USB-Serial converter IC provides a serial programming and debugging interface via a micro-USB socket, while a low-dropout (LDO) AP2114 regulator in a SOT-223 package provides a 3.3V rail. This is necessary as the ESP32 is a 3.3V microcontroller. There’s also a battery connector; an LDO regulator is needed for running from a Li-ion battery which can discharge close to 3.3V. A battery charging IC, an MCP73811T-420 in an SOT-23-5 SMD package complete the line-up. One LED near the ESP32 module’s antenna is connected to GPIO pin number 13. The module is 7mm thick due to the battery connector; if that were removed, it would be about half as thick. The battery connector is a locking type, but will also accept a standard 0.1-inch pitch female header. This board is very suitable for portable and wearable applications. Battery operation is seamless, with the option of charging during operation, while the micro-USB socket makes connection simple. The ESP32 microcontroller is from Espressif Systems and is a cousin of the ESP8266 microcontroller that we have used in various forms. Both of these can be easily programmed in the Arduino IDE through board add-ons via the Boards Manager. As well as offering WiFi, the ESP32 microcontroller can also communicate via Bluetooth. Software Most people will program the Duinotech Wearable ESP32 Development Board with the Arduino IDE. We used version 1.8.5 for our tests, but we suspect versions as old as 1.6.4 should work. Enable the ESP32 add-on by adding https://dl.espressif. com/dl/package_esp32_index.json to the Additional Boards Manager URL (in Preferences), then install the “ESP32 by Espressif Systems” option via the Tools -> Board -> Boards Manager menu. We used the latest version at the time, version 1.0.4. When installation is complete, there should be many new board options available. We couldn’t see a close match for the Duinotech Wearable ESP32 Development Board, but it appears many ESP32-based boards use the ESP32siliconchip.com.au The ESP32 Boards add-on for the Arduino IDE adds a multitude of options. We used the “DOIT ESP32 DEVKIT” board profile with the Duinotech Wearable ESP32 Development Board. WROOM-32 module; we chose the “DOIT ESP32 DEVKIT” and were able to get the onboard LED flashing. WiFi and Bluetooth Using the example sketch “SerialToSerialBT”, we were able to quickly and easily set up a virtual serial communication link to a mobile phone. This is an easy way to send commands wirelessly; it’s certainly easier than trying to toggle switches on a board that may be sewn into a garment. WiFi works as expected, with code similar to that for the ESP8266. The “WiFiScan” sketch was able to quickly give a listing of nearby WiFi access points. Accessories While there’s an incredible number of things that can be done with a bare wireless-capable board, many people will want to connect something to illuminate their wearable. With 17 GPIO pins available, there’s no shortage of potential for connecting peripherals. But the availability of addressable RGB LEDs means that even a single GPIO pin can control practically any number of LEDs. Jaycar also stocks many accessories to fill this gap. There is the WW4100 conductive thread, which can be easily connected to the development board by tying it into the large Lilypad-style pads. Flexible insulated silicone wire is also available (see Cat WH3034 and WH3036). These can all be sewn into the fabric, making it a part of the wearable. There are also a number of a directly-controllable LED “raft pads” in various colours as well as addressable RGB LED raft pads. These come in packs of five or ten. Jaycar also stocks the Sparkle Stitch Kit (shown opposite), Australia’s electronics magazine Stainless steel conductive wire (2m, Cat WW4100) can be used to easily make connections by simply tying it into connecting pads. November 2020  105 This mask is one of the many projects that can be built using the Sparkle Stitch Kit. A selection of LED “raft pads” from Jaycar. These are available in various combinations and various colour LEDs. which includes fabric, thread, electronic parts and sewing accessories. It is a great wearables starter kit, but it lacks a controller, and the Duinotech Wearable ESP32 Development Board would be an ideal choice to complement it. Sparkle Stitch Jaycar sent us a kit to evaluate. The kit contains: • 25 LED raft pads in various colours • two wearable cell holders with matching lithium cells • a wearable slide switch • conductive thread • one pair of red/black alligator clip jumper leads • elasticised thread (aka elastic band) • coloured lightweight felt cloth • Dacron filler • a hot glue gun and glue sticks • a multimeter with test leads • ten assorted needles, a threading aid, fusible tape and a plastic thimble • a thread cutter • a 62-page instruction booklet • a storage case The idea with this kit is that it contains everything you need to create wearable electronics (eg, clothes with LEDs that light up) even if you have no tools and relatively little knowledge of electronics. It would be ideal for teenagers of either gender, although we suspect that it will appeal more to girls. Having said that, which kid doesn’t want a light-up superhero costume? The instruction book is impressively comprehensive, covering not just how to wire the components together but also a great deal of information on sewing and basic electronics. A bright child (or young adult) with decent reading comprehension and the ability to follow instructions should have no trouble getting the electronics working based on the information within. One of the reasons that it is easy to follow is that it contains many clear illustrations and photos showing exactly what you need to do to achieve the desired result. The main ‘project’ in the book is a wearable LED mask (see above), and several different templates are included to produce differently shaped masks. Different colours of felt are also provided, so you can customise the shape and colours, and also the LED patterns. It also shows you how you can stick paste gems, stickers or other doodads on the mask to jazz it up. Our sample kit included large felt rectangles in tennis ball yellow, regular yellow, dark blue and red. As well as the conductive thread, it also has cotton thread in black, white, red, green, blue and yellow. The supplied multimeter is naturally a very basic one, 106 Silicon Chip but more than good enough for the sort of checks that you would need to perform when putting wearables together. The hot melt glue gun is a small, nicely decorated mainspowered type. Basically, if you want to get into wearables but are not sure what you need, or have a teenager who wants to jazz up their clothes, combining the Sparkle Stitch with the ESP32 Development Board would be a great starting point. You could then add some more accessories like extra raft pads to expand your possibilities. We think the Cat KM1040 RGB addressable raft pads would be an excellent ‘add-on’ to the Sparkle Stitch kit, for those who want to do something a bit fancier, and they don’t cost too much. Advanced users As mentioned earlier, the ESP32 Development Board also has standard header pads (and includes matching pins). There are enough pins on these to connect many peripherals. We envisage that some people will create their own ‘shields’ to stack onto the Board and give it extra features. This would be the perfect place to mount an LCD or OLED screen, or to connect an amplifier or sound module to add audio effects to a wearable project. We demonstrated Arduino code for the 3.5in LCD modules in our May 2019 issue (siliconchip.com.au/ Article/11629) and also for our D1 Mini LCD Backpack project in October this year (siliconchip.com.au/ Article/14599). That code should work with this Board although we haven’t tested it. Verdict The Duinotech Wearable ESP32 Development Board has a powerful processor, WiFi and Bluetooth. It will make an excellent basis for both simple and advanced wearable projects. The provision of battery interface circuitry also lends it well to all manner of portable projects, and not just wearables. It is available now from Jaycar stores (these are Australian prices; check the Jaycar catalog, ads or website for NZ): • Duinotech Wearable ESP32 Development Board ........................................................ (XC3810): $39.95 • Sparkle Stitch Kit .............................(KM1080): $79.00 • 2m stainless steel conductive wire .. (WW4100): $8.95 • 5 x RGB addressable raft pads ..........(KM1040): $6.95 • 10 x red LED raft pads .......................(KM1038): $6.95 • 10 x yellow LED raft pads ..................(KM1034): $6.95 • 10 x green LED raft pads ...................(KM1036): $6.95 • 5 x white LED raft pads ......................(KM1032): $4.95 SC Australia’s electronics magazine siliconchip.com.au