I am trying to use the SPI interface on an 8515 to talk to a TI TLC2543 ADC chip. Curiously, TI does not describe the ADC's interface as "SPI", but rather they just call it a three-wire interface. From the timing diagrams, however, it appears to conform fully to my understanding of the SPI protocol.
So it didn't work on the first try - probably because I got something wrong in the SPI control register set-up. Debugging it really isn't easy, though. The obvious solution would be a fast four-channel scope or logic analyzer to see what's actually on the SPI bus. Only problem is, I don't have the needed test equipment.
Is there some way to slow down the SPI interface (i.e. single-step the SPI clock) so that I could diagnose the problem using a logic probe or single-channel scope? I thought about manufacturing my own (slow) clock signal manually, but it seems that for SPI to work, one device or the other must be configured as master, and that device will then expect to generate the (full speed) serial clock signal.
Any suggestion on how to single-step the SCK output, or other general advice on how to debug an SPI interface without a logic analyzer would be much appreciated!