but a switch ain't one!

Before I get ahead of myself and work on designing a PCB and sensor cases / bracelets, I thought I should have a quick recap of the challenges that lay ahead. This is therefore a reasonably comprehensive list of difficulties that I have come across but (so far) ignored and how I think they might be overcome. Any advice would be most welcome.

1. Sensitivity adjustments - the piezo setup is temperamental at best. Sensitivity is currently adjust in the software but I need a way to adjust manually. Obviously a circuit diagram would help with this - it's next on my list - I promise!
2. Multiplexing the CE pin on the NRF24L01 - I have been thinking about this a lot over the last week and have not found a way to properly do this. Quite simply, I have run out of pins on the ATTiny. I will have a look at power usage but I may simply change to another ATMega168. This would also make the wireless coding easier as it would be the same for both receiver and transmitter.
3. Data transfer - the data being sent from the sensor does not appear to the be same as that received by the bracelet. This has made it impossible so far to use multiple sensor. I need to have see what is going on with my serial dongle.
4. Minaturisation - I have never used SMD components before and have the dexterity of an elephant. Lots of soldering practice will be needed!
5. Power supply - The plan is to run both the sensors and bracelet off CR2302 batteries. Both MCUs will need to be run on minimal current but I am not sure how much battery life I will get out of either. I was hoping for a minimum of 6 months for each.

The next post will definitely include my circuit diagram!