The PI's I2C is conveniently fully located within the first 6 pins of the GPIO, meaning we can use the same connection cable we currently use to connect to the IR lights to connect to any I2C device.
This means we could, in principle, retrofit any old PI to new interfaces, for instance by simply clamping the ribbon cable once more in the middle with a second 2x3 IDC connector. We could also modify the lightbox to interface with I2C devices inside (minding the IR light diffusion, of course).
I2C could be used to connect to the same sensors we currently use in the mesh ESP8266 Sensor mesh or to a small OLED I2C display (~£1 on Aliexpress).
Wiring on the ethoscope.
All measurements were taken with a TENMA Digital power supplier (just visual).
Power off 100mA
Booting 500mA
Idle 220-300mA
Streaming 460-500mA
Tracking 420-520mA