The hit list (or wish list) for the new design:
- 2 month battery life.
- USB results printing.
- Shrink the size of the enclosure, improve the mounting of the electronics inside.
Meeting these targets requires a many changes in different aspects of the design. 1. will require software changes and possibly hardware changes to support lower power consumption. 2. Will require an upgrade of the software and communication interfaces on the ODOTS boxes. 3. Will require a more custom design of enclosure than the current one, and a way to manufacture it. Also 2. makes 3. significantly harder when also considering the weather-proofing of the boxes as the connectors will represent a necessary break in the enclosure.
Battery life can be extended with software by introducing 'sleep mode' behaviour that allows the ODOTS device to use its RFID field less frequently if it has not been used recently. Given that the RFID field uses the vast majority of the power consumed by the device this will be able to eke out a few more days of endurance from the device. It should be noted that the devices were left on after the test in November and still responded to cards after a day and a half of being on! Excitingly modern RFID readers are gradually introducing capacitive sensing abilities. This would be ideal, allowing a permanent sleep state. Otherwise there are hardware changes that can be made to reduce power consumption, slowing down the Arduino clock-speed (or changing the micro-controller entirely) will be a good start. Ideally the entire electronic design will be looked over to search for potential efficiency gains, though this will take a while.
I have discussed the apparent need for 3d printing in redesigning the enclosures, primarily because operating one allows rapid, repeatable, bespoke manufacture. This would allow me to design an enclosure with the perfect mounting system and interior volumes for the ODOTS hardware, then produce a complete set in short order. Then repeat the process whenever the design changes (or I realise I forgot something...). Of course there is a cost involved with constructing and running the 3d printer - this will be offset by the fact that I can use it for other things, like telescopes.
