Lemming board v2.0 design

[ArcticSnow]

Discussion and notes about the Lemming v2.0 board

Main points:

• incorporate i2c isolator, i2c multiplexer
• add GPS terminal Qwiicc for Sparkfun board
• add iridium screw terminals
• add terminal for i2c multiplexer lines
• 5V output

[johnhulth]

Qwiic GPIO
https://www.sparkfun.com/products/14716

I2C isolator
https://www.maximintegrated.com/en/products/interface/isolation/MAX14937.html
http://www.ti.com/product/ISO1541

I2C multiplexer
https://www.adafruit.com/product/2717
https://www.sparkfun.com/products/14685
http://www.ti.com/product/TCA9548A#
http://www.ti.com/product/TCA9548A-Q1