From what I understand, the Extended SPI is like SPI but with extra data line.
Micron extended SPI protocol is the standard SPI protocol with additional commands
that extend functionality and enable address or data transmission on multiple DQn
lines.
I wonder how do I support it on PIC and mikroC?
There is a "simple" SPI library for that: https://download.mikroe.com/documents/compilers/mikroc/pic/help/spi_library.htm Do I have to somehow extend the hardware SPI of PIC18F, or create software SPI using any selected digital pins and write whole SPI system from scratch in my code?
I am looking at the datasheet.
The signals for READ ID command:
The pinout of chip:
For me, it looks like I can do "READ ID" in "Extended" mode just by using 4 signals: Clock (C_1), DQ0, DQ1 and S (obviously). I don't get where is the extra line needed.
My question is: where is mistake in my understanding. Can I do "READ ID" command from screenshots with simple MikroC SPI library?
The question doesn't make sense. Dual and quad SPI functions are only relevant to increase the interface throughput with SPI masters that support multiple data lines. PIC processors don't, but any flash memory function of interest can be accessed through single SPI as well, e.g. read ID.
By the way, it's not clear which chip type you are using. There's a single chip select version of the dual die memory which isn't well suited to be accessed with a classical SPI interface.