A simple Reverse Polish Notation calculator.
It uses the TM1638 module, which has 16 keys and an 8-digit 7-segment LED. The microcontroller is ATtiny1614.
Currently it implements just plus, minus, multiply and divide.
The 16 unmodified keys are used for:
- Digits 0-9,
- decimal point,
- four operators,
- enter.
A second set of 16 keys is available via long-press. So far I have only implemented (+/−) ie change sign, via long-press of the minus key.
Key layout is based on the numeric and basic operator part of classic HP calculators such as HP 42S:
| 7 | 8 | 9 | ÷ |
|---|---|---|---|
| 4 | 5 | 6 | × |
| 1 | 2 | 3 | − |
| 0 | . | enter | + |