Set the capture rate to 100 Khz, the number of samples to 1 M, and the
trigger condition on Serial Out to the falling arrow (a transition from ’1’ to
’0’) as illustrated in Figure 5.5. When configuring Saleae for other protocols,
you will need to select a capture rate that is a multiple (ideally 10 or more) of
the data rate. You will find that the Saleae logic is somewhat limiting in this
regard. For example, I have found it necessary to debug the SPI protocol at
a somewhat reduced rate in order to ensure that the Saleae logic is capable of
buffering the data. Ultimately, it may be necessary to debug at a modest rate
and, when confident everything is working, increase the underlying protocol
speed.