Scientific RPN Calculator (with ATTINY85)

[Maximilian Hohmann]

Hi deetee,

(03-23-2018 05:45 PM)deetee Wrote:  I'd like to help with "starting scary after switching on" ...

You certainly did! It now works as advertised... You really squeezed a lot of functions into those few bytes. Of course, if I had read the instructions ("reading instructions" is not something I usually do and I guess I'm not alone with that in our circles :-) ) I could have come to the solution myself.

The one time I have used EEPROM in one of my Arduino projects so far I had my software write a few unique characters into the first bytes of the EEPROM space (like it's name and version/build number). Before reading anything from EEPROM the software could check if the data was genuine and avoid working with garbage. Of course your shortness of bytes on the ATTINY85 will make it difficult to install such a feature.

One other thing: When researching double precision libraries I came across this 64bit FPU with I2C interface: http://www.micromegacorp.com/umfpu64.html Something like that would be a true revelation for every DIY calculator project. Unfortunately all distributors seem to be out of stock of even list the chip as "discontiniued". Does anybody have a source for these chips or knows of a similar replacement?

Regards
Max