Low powered pebble(ish) watch (Part 1)


Over the next few months I am going to build a watch based on the Hackaday Chronio watch.  I’ve already made a prototype of the watch, which took me over a year and a half, and over the next few months will slowly document the development process.

Before I continue let me shout out the following projects and resources used heavily in developing the watch.

Zak Kemble DIY Digital Wristwatch – Inspiration and software.

Chronio – Watch design and low power design.

Mattairtech – Board programming environment and Bootloader.

Adafruit – Software libraries and years of electronics inspiration.


The Chronio display (Sharp Memory) is no longer available so I am going to upgrade to a larger display and with that a processor with more memory to handle the larger display.  I also wanted to continue to run this from a CR2032 coin cell battery so I needed a processor that would consume little power when sleeping.

I decided to go with the ATSAMD21E18 processor from Microchip for a few reasons.  First I am familiar with Atmel range of chips.  Second, a larger Flash (256KB) and SRAM (32KB).  Third, it is Arduino compatible and has plenty of library support and can be programmed using the Arduino IDE and fourth, it has USB 2.0 Interface builtin.  Can be program via USB with an installed boot loader.

Researching SAMD21 development boards to prototype my watch I came across Mattairtech.  He has some really well designed development boards at great prices.  He also has great documentation and Arduino board managers that can be added to Arduino IDE.

I bought a MT­D21E Revision B from Mattairtech and started my prototyping.

Next Post will be more around prototyping and circuit schematic, so please tune in.



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