ESP32 port of Eric Smith's Nonpareil calculator emulator, currently planned to only support HP-15C.
Based on an early iPhone port by Tom Fors.

Emulation seems to be working well. LCD and keyboard driver is done.
Any line commented with debug could be buggy, added to make everything work for now (bodging), or completely malfunctioning. Contributions are very welcomed.

Download any library that is missing from Arduino IDE, use Arduino ESP32 filesystem uploader to upload 15c ROM into SPIFFS (since no uploader is available for LittleFS so far), then reset & check Serial Monitor.

Use this photo to find the keycode you need:

Change U8g2 constructor in esp15c.ino, check the wirings here.

Check the wirings here.
Setting up a key matrix is kind of tricky. Modify keycodeMap in Kbd_8x5_CH450.h to change mapping.
Read the datasheet of CH450 in Chinese here.

• ESP32 has more RAM than ESP8266, enough for 15c's ROM and dozens of registers
• ESP32 costs no more than 1 dollar compared to ESP8266
• ESP32 has more GPIOs, freeing us from IO expanders

I'm too lazy to optimize RAM consumptions or even implement page files. Feel free to do it on your own. :)

• 1x ESP32
• 1x CH450 keyboard scanner chip
• 40x keys
• 1x 12864 LCD or anything that is 1. big enough and 2. supported by U8g2 library.