PIC18F242 datasheet(154/332 Pages) MICROCHIP

Part #	PIC18F242

Description	High-Performance, Enhanced Flash Microcontrollers with 10-Bit A/D

PDF	332 Pages

Scroll/Zoom	100%

Manufacturer	MICROCHIP [Microchip Technology]

Direct Link	http://www.microchip.com

Logo

154 / 332 page

PIC18FXX2

DS39564C-page 152

15.4.7.1

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 15-18).

FIGURE 15-18:

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

PIC18F242 Datasheet(PDF) 154 Page - Microchip Technology