PIC18F2680ISPQTP datasheet(216/482 Pages) MICROCHIP

Part #	PIC18F2680ISPQTP

Description	28/40/44-Pin Enhanced Flash Microcontrollers with ECAN??Technology, 10-Bit A/D and nanoWatt Technology

PDF	482 Pages

Scroll/Zoom	100%

Manufacturer	MICROCHIP [Microchip Technology]

Direct Link	http://www.microchip.com

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216 / 482 page

PIC18F2585/2680/4585/4680

DS39625C-page 214

Preliminary

17.4.7.1

Clock Arbitration

Clock arbitration occurs when the master, during any

receive, transmit or Repeated Start/Stop condition,

deasserts 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 17-18).

FIGURE 17-18:

BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION

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

PIC18F2680ISPQTP Datasheet(PDF) 216 Page - Microchip Technology