This program is used to control a HIIT stopwatch. In high-intensity interval training, there is always an active phase in which an exercise is performed and a relaxation phase until the next exercise.
A specific duration can be set for each of the two phases. After starting the clock (long press), the set time intervals are counted down alternately. When a countdown reaches zero, an acoustic signal sounds and the next countdown begins.
A rotary encoder is used to enter the values and control the clock. The output device is a 128x64 pixel OLED display.
If no input is made at the clock, the circuit is put into a sleep mode to save power. The power consumption in sleep mode is about < 10µA. To end this, a short press on the encoder button is also sufficient.
This version is customized to an ATtiny 1614. A crystal is connected to the Attiny 1614 so that the time function is more accurate.
Breadboard view (Click on the photo to see a video on Youtube.)
Power consumption during operation
Power consumption during deep sleep
