RPN-duino

[Chasfield]

To step up the calculator's functionality while remaining inside the Arduino eco-system is problematic. The BigNumber library offers much more precision than the 6-7 digits of the standard 32 bit Math library currently in use but I don't think it can co-exist with the u8glib display library for want of space on the Arduino Nano. A lean display driver, or an equally lean 40 bit maths library would sort the problem.

I have solved the dim display problem. Apparently, the default display contrast is 50% percent of the max that can be set by writing a byte to the display contrast register on the SH1106 display chip. The code to support this is in u8glib v1.19.1 but this version seems problematic on my Xubuntu Arduino IDE. However, I was able to append the code to the appropriate source file in v1.18.1 so the contrast level can now be adjusted.