Thursday, 18 April 2019

Size matters more than ever

A few years ago I commented on how a smaller board makes more projects possible. Then it was comparing an Arduino Uno with a Nano.

Now I'm looking at the ESP8266 boards I've been using and thinking about the practicalities of building a wearable sensor/tracker. While I can never hope to replicate the level of integration in a commercial project I am looking for something to keep it as small as possible.

I had been working on some sneaky use of the pins on an ESP-01 module in my first prototype but it's still quite chunky and the 8-pin header makes it quite tall.

Time marches ever on and now decently packaged ESP8285 modules have appeared in the usual places. These are a minor update to the old faithful ESP8266 with integrated flash memory but otherwise backwards compatible. The integrated flash makes for a slightly smaller module and offers a certain guarantee of the quality of that flash as it's coming straight from Espressif. Some cheap ESP8266 based modules come with questionable quality flash memory.

Here's a Wemos D1 Mini, ESP-01 and the new ESP-M2. It doesn't save you much over the ESP-01 but it delivers a ton more pins and can be surface mount soldered onto a board.

Now all I need to do is make a breakout board so I can do some testing with it before I have some boards made.

Saturday, 13 April 2019

D1 Mini breakout

I'm a big fan of the Wemos D1 Mini and Mini Pro as the basis of microcontroller projects.

They're cheap, the ESP8266 chip is powerful and can be used with several development environments/languages. You can program them in C/C++ with the official Espressif SDK, but also the Arduino IDE where support is excellent. They'll also run more modern interpreted languages like MicroPython and Lua, again with good support if some memory limitations.

Most of the time, people consider ESP8266 boards for IoT type projects but you don't have to use the WiFi, it can be switched completely off and at heart they're a 80/160Mhz 32-bit device with enough GPIO to handle many small projects. About the only thing they suck at is low power/sleep which is poorly implemented by comparison with other modern boards.

What they do lack is such a large ecosystem of 'shields' and breakouts. Wemos make their own but they're all a bit 'Arduino sensors 101' type things.

I saw these chunky screw terminal breakout boards mentioned on Twitter and while I have no immediate use for them I picked a couple up because I know they'll be great for prototyping stuff.