PIC18F45J10 FAMILY
SCLx pin is sampled high, the Baud Rate Generator is
reloaded with the contents of SSPxADD<6:0> and
begins counting. This ensures that the SCLx high time
will always be at least one BRG rollover count in the
event that the clock is held low by an external device
(Figure 16-18).
16.4.7.2
Clock Arbitration
Clock arbitration occurs when the master, during any
receive, transmit or Repeated Start/Stop condition,
deasserts the SCLx pin (SCLx allowed to float high).
When the SCLx pin is allowed to float high, the Baud
Rate Generator (BRG) is suspended from counting
until the SCLx pin is actually sampled high. When the
FIGURE 16-18:
BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION
SDAx
DX
DX – 1
SCLx allowed to transition high
SCLx deasserted but slave holds
SCLx low (clock arbitration)
SCLx
BRG decrements on
Q2 and Q4 cycles
BRG
Value
03h
02h
01h
00h (hold off)
03h
02h
SCLx is sampled high, reload takes
place and BRG starts its count
BRG
Reload
© 2009 Microchip Technology Inc.
DS39682E-page 179
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