PIC18F4610-I/ML 查看數據表（PDF） - Microchip Technology

零件编号

产品描述 (功能)

生产厂家

PIC18F4610-I/ML

28/40/44-Pin Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

Microchip Technology 

PIC18F2X1X/4X1X

16.4.17.3 Bus Collision During a Stop

Condition

Bus collision occurs during a Stop condition if:

a) After the SDA pin has been deasserted and

allowed to float high, SDA is sampled low after

the BRG has timed out.

b) After the SCL pin is deasserted, SCL is sampled

low before SDA goes high.

The Stop condition begins with SDA asserted low.

When SDA is sampled low, the SCL pin is allowed to

float. When the pin is sampled high (clock arbitration),

the Baud Rate Generator is loaded with SSPADD<6:0>

and counts down to 0. After the BRG times out, SDA is

sampled. If SDA is sampled low, a bus collision has

occurred. This is due to another master attempting to

drive a data ‘0’ (Figure 16-31). If the SCL pin is

sampled low before SDA is allowed to float high, a bus

collision occurs. This is another case of another master

attempting to drive a data ‘0’ (Figure 16-32).

FIGURE 16-31:

BUS COLLISION DURING A STOP CONDITION (CASE 1)

TBRG

TBRG

TBRG

SDA

SCL

SDA asserted low

PEN

SDA sampled

low after TBRG,

set BCLIF

BCLIF

P

‘0’

SSPIF

‘0’

FIGURE 16-32: BUS COLLISION DURING A STOP CONDITION (CASE 2)

TBRG

TBRG

TBRG

SDA

SCL

Assert SDA

SCL goes low before SDA goes high,

set BCLIF

PEN

BCLIF

P

‘0’

SSPIF

‘0’

© 2007 Microchip Technology Inc.

Preliminary

DS39636C-page 189

Share Link: