So as my favourite form of exam (or general) procrastination, I’ve been designing a new smartwatch! This one is based on the new STM32 range and will include a TSSOP (http://goo.gl/TAUKS8) microcontroller instead of a pesky QFP (http://goo.gl/ccKwXR), they’re not particularly different other than the TSSOP package doesn’t have pins on all 4 sides. I’ve not actually added too many changes other than changing the power system to my newly designed 2.8v one and i’ve also rounded the corners of the board, much nicer than chodey square corners! The LCD also sits directly on the mainboard PCB instead of being attached by a seperate header, reducing the depth! The new dimensions are roughly 46.5x41x9mm. I’ve also changed how i’m going to attach the straps (note the holes in the routed sections on the top middle and bottom middle of the board. The watch will also include a 2mm JST connector (http://goo.gl/6RNzIN) for charging and programming access.
Watch outline with new additions.
This is the first time that I’ve ever had PCB’s routed out at ITEAD studio so I hope it goes well!
I’ve also started the design for Watch 3. Having researched all smart watches currently available, it seems that nearly all of them feature some form of bluetooth capability. As of this, I’ve bought some HC-06 bluetooth modules (http://goo.gl/7YGaiX) off eBay which should arrive soon! Watch 3 will hopefully include bluetooth and the processor will be one of the STM32L range (http://goo.gl/FyGWSL), highly suitable for low power usage, with apparently world records in low power consumption!
The HC-06 modules are really cheap when bought from Asian countries, I’ve bought one from the UK and from China. The UK board will be used for all the testing and by the time the Chinese board arrives, I should have sent off designs for Watch 3. I’m going to be doing all the testing using my trusty Arduino Nano as it has really easy serial control and only takes up one usb port! The software serial library apparently works really well with the HC-06 boards anyway so thats good. I’m hoping as a start to just pair the bluetooth and send a small message from my phone using BlueTerm. Once I get this to work, I can get set on designing my own Android app to send simple features (ooooh!). Having never really programmed C++/Java/Anything OOP, this will be a really good learning challenge as I could do with knowing the simple stuff about OOP when I go to work this summer at Imagination.
Bluetooth should hopefully really put the watch in pebble territory other than size! The current watch in sleep mode can achieve around 2 weeks of battery life so with periodic wakeups, the battery life should sit at 1 week. With continuous bluetooth usage, I’ve calculated a battery life of around 6 hours which is comparable to other bluetooth streaming devices. Unless I implement headset/A2DP, bluetooth won’t be streaming data to the watch. If I get chance, I might implement a simple Piezo speaker on the watch so keep tuned!