Reprogram Default Character Set

I recently posted about fixing some bugs with a MAX 7456 overlay setup. They are fixed, I needed to adjust some register calls. While troubleshooting, I got the dumb idea that there was residual data in the default character memory that was disrupting the new characters being written. I decided to write clear characters over the entire default character memory. Now, naturally, there is nothing there. Is there a way to reset the MAX7456 chip to its factory defaults?

I didn't see anything in the the datasheet about restoring the character NVM (EEPROM). I suspect you will have to find the data somewhere and upload it.

Looks like the evaluation kit includes defaultCM.mcm which contains the default character set:

On page three of the MAXIM Eval Kit:
“… the MAX7456 and the MAXQ2000 have different supply voltages, …”
“Note that the MAX7456 EV Kit software does not communicate directly with the MAX7456.”
I am familiar with the .mcm and .mdm memory files; how can they be uploaded to the MAX 7456 chip? The Arduino doesn’t read files like those.

Since I’m not paid to sit around, I started rebuilding the character memory from scratch, the code for that is attached (The uppercase letter “B”). I hope you never have to do this.

Here’s the function write_charB() code.

build.txt (14.7 KB)