An ESP32 port of Eric Smith's Nonpareil emulator. Designed for HP Voyager calculator emulation.
The successor of shezik/esp15c (now archived).
To perform a firmware update, visit espnut-updater.

Features

• Matrix keyboard driver for ESP32-S3 that doesn't support dedicated GPIO interrupt :)
• Power management
• State saving & loading
• Graphical menu and file manager
• Synthetic programming support for HP-15C (y^x + ON)

Todo (Sorted by priority)

• Remove excess variables saved in state file
• deleting empty directories
• Logging and accessing logfile
• Read comments marked with '!!'
• Apply ROM patches dynamically
• Add ESP32 cpu frequency options to Menu

Schematics are available here.

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Porting to unicore chips

This project utilizes the auxiliary core of ESP32-S3 to scan the matrix keyboard. You'll need to take care of the xTaskCreatePinnedToCore function called in src/MatrixKeyboard.cpp, though I suppose that ARDUINO_RUNNING_CORE would also be 0 in this case.

Additionally, check commit 7db65a if watchdog is often triggered. You'll probably want to replace yield() with vTaskDelay().

Also confirm that there's enough RAM that fits the ROM files.