Re: SPI Software
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There are a lot of variables to SPI, it is not a properly defined protocol. Does data change on the positive or negative clock edge; is it LSB first or LSM first? Does LE/CE have to be held active for the duration of the data transfer, or is it pulsed at the end? Is the active edge low going or high going?
For I/O devices, are there separate IP and OP wires, or is the D line tristate?
Every ine of these can be different
So you see there can be no standard chip or interface, every one has to be customised. WHich is why a programmable device like a PIC or something else is aways used