Datasheet

PIC16(L)F1824/1828
DS41419D-page 276  2010-2012 Microchip Technology Inc.
25.6.2 CLOCK ARBITRATION
Clock arbitration occurs when the master, during any
receive, transmit or Repeated Start/Stop condition,
releases the SCL pin (SCL allowed to float high). When
the SCL pin is allowed to float high, the Baud Rate
Generator (BRG) is suspended from counting until the
SCL pin is actually sampled high. When the SCL pin is
sampled high, the Baud Rate Generator is reloaded
with the contents of SSP1ADD<7:0> and begins count-
ing. This ensures that the SCL 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 25-25).
FIGURE 25-25: BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION
25.6.3 WCOL STATUS FLAG
If the user writes the SSP1BUF when a Start, Restart,
Stop, Receive or Transmit sequence is in progress, the
WCOL is set and the contents of the buffer are
unchanged (the write doesn’t occur). Any time the
WCOL bit is set it indicates that an action on SSP1BUF
was attempted while the module was not Idle.
SDA
SCL
SCL deasserted but slave holds
DX ‚ – 1DX
BRG
SCL is sampled high, reload takes
place and BRG starts its count
03h 02h 01h 00h (hold off) 03h 02h
Reload
BRG
Value
SCL low (clock arbitration)
SCL allowed to transition high
BRG decrements on
Q2 and Q4 cycles
Note: Because queueing of events is not
allowed, writing to the lower five bits of
SSP1CON2 is disabled until the Start
condition is complete.