Here is what I am thinking for a first carrier board. Before I lay out the board, I thought I would share the schematic and see if anyone has comments or suggestions. My plan will be to build a few, test them in the field for a month or so and then finalize the design. I will document and share everything.
Use case: This is a carrier for the Particle Electorn 3G for use outdoors. I want to be able to either power it from 5V @2A or with a Solar Panel. The device will remain on but will use sleep and sensor interrupts to save power while recording events. Data will be cached / stored locally on FRAM and reported on an hourly basis as long as there is data to send.
- 2 ic2 bus connections with one configurable to either 3.3V or 5V
- The Power line, i2c lines and four digital lines will be ESD protected ( may need to add Earth ground)
- Powered either by a 5V 2A wall wart or by a Solar panel
- Easy connections to all A and B bank IO.
- Push on - Push Off button for the LiPo battery making it easy to turn on and off when on battery power
- 256k FRAM module on board (you can choose to populate or not)
- Kill line would allow the Electron to turn itself off if the power fails and the battery gets too low.
So, what did I miss? Any suggestions?