https://github.com/cedargrovestudios/cg-35_calculator

A CircuitPython RPN Calculator
https://github.com/cedargrovestudios/cg-35_calculator

circuitpython hp-35 retro rpn-calculator

Last synced: about 1 month ago
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A CircuitPython RPN Calculator

• Host: GitHub
• URL: https://github.com/cedargrovestudios/cg-35_calculator
• Owner: CedarGroveStudios
• License: other
• Created: 2022-01-10T00:40:41.000Z (almost 3 years ago)
• Default Branch: main
• Last Pushed: 2023-11-02T03:57:30.000Z (about 1 year ago)
• Last Synced: 2023-11-02T04:30:45.024Z (about 1 year ago)
• Topics: circuitpython, hp-35, retro, rpn-calculator
• Language: Python
• Homepage:
• Size: 67.4 MB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Retro RPN Calculator

The CG-35 is a CircuitPython powered HP-35-like RPN calculator for the Adafruit ESP32-S3 Feather and 3.5-inch TFT FeatherWing display with capacitive touch. The calculator

consists of a 10-digit LED display with 20-digit internal calculation precision. The emulator code is augmented by the micropython `udecimal` library adapted for CircuitPython by @jepler (Thank you!).

![The CG-35 Retro RPN Calculator](https://github.com/CedarGroveStudios/CG-35_Calculator/blob/main/photos_graphics/IMG_1988.jpeg)

The CG-35 calculator emulates the HP-35 calculator's v2.0 firmware where the change

sign (CHS) key is active only after digit entry has begun. Calculation accuracy

of monadic, dyadic, and trigonometric functions was improved. An error descriptor

message area just below the primary display was added.

The calculator's graphical layout was designed to mimic the aspect ratio of the

original calculator. Because of the relative small size of the buttons,

touchscreen accuracy is important, requiring the use of a capacitive touch

screen rather than a resistive touch screen.

For audible key press and status feedback, connect a piezo speaker from

pin A0 to ground.

* Author(s): JG for Cedar Grove Maker Studios

* GitHub: 

Implementation Notes

--------------------

**Hardware:**

* Adafruit 'ESP32-S3 4Mb/2Mb FeatherWing

  

* Adafruit 'Adafruit TFT FeatherWing - 3.5" 480x320 Capacitive Touchscreen

  

**Software and Dependencies:**

* Adafruit CircuitPython firmware for the ESP32-S3 FeatherWing:

  

* Jeff Epler's adaptation of micropython `udecimal` and `utrig`:

  

* CedarGrove's `SevenSeg-12.bdf` font:

  

Optional/future features:

- Implement display brightness control.

- Adjust for automatic scientific notation conversion for entered values < |1| with a negative exponent > -6. This is an inherent behavior of the Decimal class in micropython, CircuitPython, and CPython.

- Purge the T register when calculating trigonometric functions to fully emulate the HP-35 process.

- Incorporate a selectable degrees/radians mode with indicator (enhancement).

- Incorporate a selectable scientific/engineering/fixed decimal point mode (enhancement).

- Add a setup button for setting initial parameters (enhancement).