My "Library" for ST7920 Graphical displays, works fine, but...

[tumbleweed]

If you're trying to write something totally generic that can be used with all the 8-bit PIC's then the most generic solution is to use the bit-banged I2C routines.

If you want a faster method then using the MSSP hardware is the solution, but-
a) not all PIC's have an MSSP module
b) even if they do, they all don't work quite the same, so there may be some slight differences in programming

SPI is simpler and faster than I2C but will take 4 pins instead of 2.
Either way, you will be limited as to which pins can be used... bit-banged can use pretty much any pins but the MSSP uses fixed pins.

If somebody required me to use a parallel EEPROM for something like this I'd laugh and say "no thanks".

[CuriousOne]

Well I tried software SPI with MAX7219 and was not impressed at all - updating 32x8 pixels led display was quite slow....

[HenrikOlsson]

So if you have simple, clean to understand code for working with MSSP in PBP, I'd like to have a look...

I'll just point to MELABS: https://melabs.com/samples/PBP-mixed/spimast.htm That example is what I used as a basis when I first used the MSSP module for SPI (for interfacing the W5100 (search the forum for that code if you want)). See, not a single line of assembly.

[CuriousOne]

Thanks, but that code is missing SSPBUF declaration?

[HenrikOlsson]

No.
SSPBUF is the Synchronous Serial Port Receive Buffer/Transmit Register. It's the name of register to/from which you write/read whatever gets shifted out.

[CuriousOne]

Good.
So I have to "learn" to use SPI eeprom 1st, and then use MSSP
By the way, if I leave current setup as is - using I2C, but use PIC running at say 32mhz (instead of current 8mhz), will this result 4x times faster reading speed or not?

[HenrikOlsson]

Have you measure what clock speed you're getting?
Standard "high speed" I2C clock is 400kHz, maximum clock speed of a Microchip 24C256 when run at >2.5V is 1MHz.
SPI-interface flash chips usually has a maximum clock frequency of at least 33MHz.