With the deadline for the next stage of the Hackaday Prize looming, a brief update is probably necessary:

While progress on this project is still ticking along slowly (I'm just bad at continuous project logging), the boards for the next hardware iteration won't be here for another couple of weeks, let alone the deadline in a few hours. As such, I can't show a video of it working, making it a bit difficult to qualify for the next set of judging. On that note, a lot of the other current entries out there look really awesome - I can't wait to see how some turn out.

The circuit design for the next hardware iteration turned out to be more of a drastic change than I'd originally planned - the only component in common is the LIS3LV accelerometer (the HIH6131 humidity/temp sensor has been replaced with the more accurate, but otherwise identical, HIH9131). Of particular note is the removal of the ATmega328P - I'm attempting to do all the sensor logic in the new Bluetooth module, rather than a separate microcontroller. The Bluetooth module being used for this is actually pretty interesting - a BlueGiga BLE113. This module allows applications written in a script langauge to be run on the same hardware that manages the Bluetooth comms, with access to several GPIO ports, UARTS, and SPI. It is also a Bluetooth Smart device, and so should draw considerably less power than the previous iteration.

Battery management and power regulation is now handled by an LTC3553 - a really useful chip made by Linear Technology that incorporates a USB LiPo battery charger, a buck regulator, and an LDO regulator into one device. By default the LDO is not being used in the new iteration, but a jumper has been included in case the switchmode regulator turns out to interfere with the Bluetooth in testing.

Much of the last week has been spent getting my 3D printer up and running again, so I should have some new enclosure designs ready in a week or two. One of the largest challenges I'm having with this at the moment is designing an enclosure that is both strong and light enough - it needs to handle being rolled on top of when the wearer is sleeping.

Even further ahead, once the new PCBs are together and working, is the Android app redesign. A lot of the app will need to be rewritten from scratch, as the APIs dealing with Bluetooth Smart in the newer versions of Android differ significantly from the old (admittedly horrible) interface to Bluetooth Classic.

It might be a while until the next update, but if anyone has questions, please don't hesitate to ask.