I2CWRITE writing Strings to EEPROM

[NavMicroSystems]

Undocumented Feature?

On one of my current projects I had the challenge to store about 300 strings
(up to 20 chars each)

The strings contain system messages
and a (very) complex menu structure.

I decided to store the strings in an external EEPROM (24FC512)
which was already on board for data logging.

After having done some first tests I had to realize that
every time when I had a firmware update that required changes in Menu text or system messages
I had to take the EEPROM off the board, reprogram it and plug it back.

This is certainly nothing a customer could do.

So I thought I needed some kind of Loader for the EEPROM.

The trick is:

Write the string to the EEPROM:

(The PBP Manual doesn't tell this is possible)

IC2WRITE SDA, SCL, ADR, [20,"This is my String #1"]
where 20 is the length of the srting.

My finding is:
This "Page Write" works great as long as ADR is a multiple of 32.
(haven't tried odd multiples of 16 as my Strings are up to 20 bytes)

Next step is to "compress" the Data we have just written to the EEPROM.
(We used up 32 bytes for 21 Bytes of information)

Read the EEPROM content bytewise and write it back bytewise
and use a multilpe of 21 for the starting address of a new string.

And finally (if you want to) fill up all "unused" locations with $FF

So in case the Strings in EEPROM are to be updated along with Firmware of the PIC
all the customer needs to do is:
Flash the device twice,
1st with the EEPROM Loader that does the EEPROM update
and then with the latest Firmware.

regards

Ralph