RPN scientific calculator firmware for $13 calculator kit

[toml_12953]

(10-28-2019 08:17 PM)jklsadf Wrote:  One last thing I just thought of...in order to fully turn off the calculator so that it can be turned on again to run the bootloader, it might be necessary to prevent the microcontroller from being parasitically powered through the serial port pins if you have the USB-to-serial adapter connected..

The easiest way to do that is to unplug the USB-to-serial adapter from your computer while turning off the calculator.

That was my problem! I had removed the batteries but the USB serial converter was plugged in. When I removed it from the computer and plugged it back in, the download executed. Now I have two RPN calculators and I'll have to buy a third DIY to have one in original shape unless I can get the hex file for the resistor color code calculator.

Thanks for the help. I've uploaded a revised key layout to Dropbox. It has slightly darker numeric keys and the trig functions are on keys 1, 2, 3 and the arc function is on the minus key. I followed your idea for them.

DIY Keyboard Template