PIC18F4539-ESLASHMLSQTP datasheet(154/322 Pages) MICROCHIP

Part #	PIC18F4539-E/MLSQTP

Description	Enhanced FLASH Microcontrollers with Single Phase Induction Motor Control Kernel

PDF	322 Pages

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Manufacturer	MICROCHIP [Microchip Technology]

Direct Link	http://www.microchip.com

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154 / 322 page

PIC18FXX39

DS30485A-page 152

Preliminary

 2002 Microchip Technology Inc.

16.4.7.1

Clock Arbitration

Clock arbitration occurs when the master, during any

receive, transmit or Repeated START/STOP condition,

de-asserts 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 SSPADD<6:0> 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 16-18).

FIGURE 16-18:

BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION

SDA

SCL

SCL de-asserted 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

PIC18F4539-E/MLSQTP Datasheet(PDF) 154 Page - Microchip Technology