PIC16F1459-ESSQTP datasheet(236/418 Pages) MICROCHIP

236 / 418 page

PIC16(L)F1454/5/9

DS41639A-page 236

Preliminary

 2012 Microchip Technology Inc.

22.6.2

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 Gen-

erator (BRG) is suspended from counting until the SCL

pin is actually sampled high. When the SCL pin is sam-

pled high, the Baud Rate Generator is reloaded with

the contents of SSPADD<7:0> and begins counting.

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 22-25).

FIGURE 22-25:

BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION

22.6.3

WCOL STATUS FLAG

If the user writes the SSPBUF 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 does not occur). Any time the

WCOL bit is set it indicates that an action on SSPBUF

was attempted while the module was not idle.

SDA

SCL

SCL deasserted but slave holds

DX ‚

– 1

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

SSPCON2 is disabled until the Start

condition is complete.

PIC16F1459-ESSQTP Datasheet(PDF) 236 Page - Microchip Technology

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