Thanks for the suggestions. I fully agree that this platform must allow to easily plug some additional components.
At the moment, instead of considering a edge connector, I have in mind a HE10 connector that could receive either a board, or a ribbon cable connector (a board for applications like the ECG, and a ribbon cable to interconnect Primers or to test a simple sensor without developping a new board. A HE10 connector is a low cost, easy to handle solution.
For the list of the signal on this connector, I propose the following definition (for a 16 pin connector):
Vcc-OUT GND
I2C-SCL I2C-SDA
(SPI) MISO MOSI (SPI)
(SPI clock) SCK GND
CANH CANL
I/O-Timer I/O-Timer
I/O-AIN I/O-AIN
Vcc-IN GND
Vcc-out would allow to power an external device, and Vcc-In would allow to reload the internal batteries if the Primer is (for example) connected to a Robot with a strong battery.
At the moment, I agree for adding buttons, but I discard the joystick for two reasons:
1. The joystick will make the design of the box more complex and more expensive. We want to keep a low price (and a large volume) to keep a wide international community,
2. Our idea is to improve the handling of the MEMS that will have the same function. We have seen that the current management of the MEMS is not convenient enough (the Chess game is pretty nice, but very difficult to play!). We should find solutions to adapt the MEMS information to the situation. That's will be the goal of the next release of the CircleOS.
The idea to keep a small window (slot) for the connected board is fine too.
Again, thank you very much for your suggestions.
