Bracelet block diagram shows all necessary HW modules. Since we have defined the necessary HW modules, we use FINDCHIPS for search of needed components like MCP73831.
For user to be able to set the alarm feature and to select sensitivity for the automatic vibration feature (triggered by surrounding sound), two buttons are needed. We will use microphone amplifier: Variable Gain Amplifier (VGA) for automatic vibration sensitivity adjustment which will allow users to set best suited sound level at which the bracelet will vibrate.
The processor with DSP support will perform real-time signal processing.
We are still in a process of research for the best power supply solution, based on price/ functionality ratio. At one side developing countries have the most potential bracelet users and if we want to make that bracelet is affordable for everyone, users should be able to replace the battery with new one bought buy themselves (similarly to hearing aid battery replacement). On the other side, full feature bracelet should have a rechargeable battery that can be recharged via a USB port. USB port would also enable software upgrades possibility.
So we have decided to use replaceable batteries for initial version of bracelet (minimum viable product - MVP).