Hi at all,
thank you for your response and interest. Oh there are a lot of questions. I'll try to answer them.
>>> Will you be sharing your design and software?
That's no problem but first I have to clean the code, finish my user manual and the box is not quite perfect yet. The project is not ready. So please give me some time to finish everything.
>>> Perhaps a video demonstrating its function?
That's a very good idea. I guess I can do this very quick (I hope so).
>>> is the full Hexbus spec implemented?
Unfortunately not. I have only implemented things that I need for my calculator.
For example you can "old", "save" and "verify" programs (a kind of binary file).
With "list" it writes a plain text file, the source code.
"delete" deletes a file, "run" starts a program directly from sd card.
Data files can be written "sequential" or "random" with "display" or "internal" mode from basic program or basic prompt.
But this data access is not tested fully. I have to write a test program...
Within the calc mode of the TI-74 you can use the "print" function to print the content of the display to the connected pc.
The device uses the sdFAT library to manage the SD access. So the SD card is formated with FAT32 and limited to 32GB. But this should be more than enough for the 7710 Bytes of RAM. The SD card can be mounted and accessed without any problems from a PC.
One example for things that are not implemented are master and slave modes (I haven't understood it yet and I don't know if the TI-74 supports this). My device is always slave.
>>> is your source radically different from the version I have...
First I had a short look to your code. But to be honest I didn't understand it.
My programming skills where (and still are) not the best.
So I decided to learn how the communication works and how to program a microcontroller.
I managed it, but now the capacity of the microprocessor is at the end. This problem I have to solve next.
So I'm not quite sure If you can use something from my code and yes the code is very different.