Help about SPI

[Gpdy]

I'm learning the SPI with the pic18f4520.
In datasheet it was set as:

[andrewg]

CCS have two different ways of accessing the SPI bus. I would pick one or the other and not mix them (unless I *really* knew what I was doing).

The first is the setup_spi, spi_read and spi_write functions. These all access the *hardware* SPI device. Hardware SPI has a limited number of pins you can use. Usually you have no choice at all which pin to use - you must use the hardware pins allocated to SPI.

The second method is #use spi with the spi_xfer function. This allows you to define a software SPI bus on just about any pins you like. You can also use the hardware support too.

Since you want to use pins that aren't assigned to the SPI hardware, you must use a software SPI, and that means you must use "#use SPI" and spi_xfer.

A third option is to "bit bang", where you use output_high, output_low and output_float to control the SPI bus signals manually. I've had to do that recently when I goofed my PCB design and swapped the data in and out connections on an SPI device. That's what prototypes are for!
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Andrew