hex-calc

Simple Hex/Binary/Decimal calculator inspired by HP-16C and TI Programmer.

large image

Features:

• Hex / Decimal / Binary display in signed or unsigned mode
  • Entire stack for 8/16 bits, two levels for 32 bits
• four-function two-compliment or unsigned arithmetic
• 8 / 16 / 32 / 64 bit word size
• four-level RPN stack with roll / swap

Runs on ATMeg328 at 8MHz. Power is 4xAA batteries regulated to 5V. Industry-standard 16x2 backlit LCD. Three LEDs:

• Power
• f key (function/shift) active
• signed display mode

Code in src/calc_hw.

KiCAD design in keyboard-pcb.

See https://github.com/eshazen/calc-demo-xwin for an X-windows app written in C which illustrates the general idea.

Enhancements

Thinking about some added features to support fractional arithmetic for woodworking. Display options to round to nearest fraction (1/4, 1/8, 1/16, 1/32, 1/64) and switch between decimal inch, fraction inch and decimal mm. Ft/inches another useful display option.

This would involve either floating point or scaled integer math. For this application the range is pretty limited, maybe 8 ft (~100 in) max.

Base units could be 2.54e-6 in (1um). 100 inches would require ~25 bits.