SPI Wave Forms

[richard.c]

Hi,

Have just been experimenting with a simple SPI routine from two 18F4520 Pics in a typical manner based on Microchips SPI tutorials code, just sending out a character and getting one back, in a closed loop.

I've connected the three signal lines to the PK2 Logic tool and it displays the waveforms in the order SCK, master SDO, master SDI.

While the clock and SDO signals seem obvious, the SDI signal has an addititonal smaller burst preceeding what I assume is the following byte of data.

Does anyone know what this smaller burst is ?

thanks

 

[felis]

What number are you transmitting? And which one of 4 SPI modes is configured?

 

[richard.c]

Opps.. my mistake, it was returning an extra bit when I thought this was the same ..