Iot123 - Sr04 Distance Trigger Brick

In developing an OLED ID Tag, I needed to make my design as energy efficient as possible. One approach was to only display the tag if there was someone nearby (think ComiCon or Exhibition booths). The sensors themselves can draw a lot of current, so this needed to be optimized. Originally I started with a Sharp IR sensor, but bricked my only one during a development spike.
I believe there are many scenarios where low power sensing is required, so I made the design fairly generic where the hardware sensor and the associated code could be swapped out easily. Also serial pins (TX/RX) have been broken out so as to debug the ATTINY85 during development. When a predefined (runtime assignable via a momentary button) value is reached, a pin is sent HIGH, to wake the HOST MCU. When not triggering/sensing, the ATTINY/SR04 are sleeping/powered down.
The mashup has been coined a BRICK as a nod to the ubiquitous Keyes bricks.”