Calculator

Calculator running on CircuitPython firmware with a Feather RP2040 with DVI output, driven by a 5x4 matrix keypad.

Hardware

• Adafruit Feather RP2040 DVI
• 5x4 matrix keypad, diodes pointing toward the columns (cathode at column, anode at row)
• HDMI/DVI display — tested target is a 7" 1024x600 panel, driven at 800x480 (panel scales it down)

Keymap

x      ^      √      ÷
7      8      9      X
4      5      6      -
1      2      3      +
clear  0      .      sum

(√ and ÷ show as the real symbols on-screen via the custom font which a extraction of the baisic one to preserve memory)

Usage

Basic math — type a number, an operator, another number, then sum to evaluate. Chained expressions evaluate left to right x as a variable

• x 3 sum → stores 3 into x (the screen shows x=3)
• x + 5 sum → substitutes the stored value of x into the expression
• Pressing x with nothing stored yet and using it in a calc shows an x undef error √ (root) — binary, first number is the degree, second is the radicand: 2 √ 9 sum → 3 (square root of 9). 3 √ 27 sum → cube root of 27.

clear

• single press → clears the current entry/expression only
• triple press within ~0.6s → also wipes the stored x value (shows mem cleared)

Case

I dint yet make the display part of the case as im planning to do tht after i get it