Latest firmware version v0.901

Minor fixes.

Download Firmware v0.901

* NEW: 2-Line display for the PX-15C.

To display 2 lines on the PX-15C, go to the advance page in settings and set REGY to 1.
Download PX-15C 2-line Oct-13-2023 firmware.

Firmware version v0.90


Many thanks to Guido for his extensive bug hunt and new ideas.
Please take you time to see Guido's RPN calculators page.

Download Firmware v0.90

Firmware version v0.89

Download Firmware v0.89



Firmware version v0.85:

Firmware version v0.81:

First Release: Firmware version v0.80:

Known Issues:

WARNING!: Pressing the reset key or uploading new firmware will erase all user content (programs and registers)!

Loading New Firmware:

To load new firmware, you need a standard AVR SPI (Serial Peripheral Interface) programmer. Such as the usbasp.
You can even use an Arduino Uno as a ISP programmer.

Also, you will need avrdude or some other software to program the microcontroller.

Most AVR programer have a 6 pin (2x3) or 10 (2x5) pin header. The calculator uses a 6 pin (1x6) header. So you will probably need to buy an adaptor or simply make one.

I simply cut the ribbon cable and solder a 6 pin male header.

Be sure the voltage on the programer is set to 3V, failure to do so will destroy the LCD.
Remove the battery or disable power on the programmer. Use only ONE power source.

Programming Adaptor Image Gallery.