PIC18C452T-E/L【PDF 32/279 页】IC MCU OTP 16KX16 A/D 44PLCC

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录3889

28页 29页 30页 31页 [32页]33页 34页 35页 36页

2001 Microchip Technology Inc.

DS39026C-page 125

PIC18CXX2

14.3.5

SLAVE MODE

In Slave mode, the data is transmitted and received as

the external clock pulses appear on SCK. When the

last bit is latched, the SSPIF interrupt flag bit is set.

While in Slave mode, the external clock is supplied by

the external clock source on the SCK pin. This external

clock must meet the minimum high and low times as

specified in the electrical specifications.

While in SLEEP mode, the slave can transmit/receive

data. When a byte is received, the device will wake-up

from SLEEP.

14.3.6

SLAVE SELECT

SYNCHRONIZATION

The SS pin allows a Synchronous Slave mode. The

SPI must be in Slave mode with SS pin control

enabled (SSPCON1<3:0> = 04h). The pin must not

be driven low for the SS pin to function as an input.

The Data Latch must be high. When the SS pin is

low, transmission and reception are enabled and

the SDO pin is driven. When the SS pin goes high,

the SDO pin is no longer driven, even if in the mid-

dle of a transmitted byte, and becomes a floating

output. External pull-up/pull-down resistors may be

desirable, depending on the application.

When the SPI module resets, the bit counter is forced

to 0. This can be done by either forcing the SS pin to a

high level, or clearing the SSPEN bit.

To emulate two-wire communication, the SDO pin can

be connected to the SDI pin. When the SPI needs to

operate as a receiver, the SDO pin can be configured

as an input. This disables transmissions from the SDO.

The SDI can always be left as an input (SDI function),

since it cannot create a bus conflict.

FIGURE 14-4:

SLAVE SYNCHRONIZATION WAVEFORM

Note 1: When the SPI is in Slave mode with SS

pin control enabled (SSPCON<3:0> =

0100

), the SPI module will reset if the SS

pin is set to VDD.

2: If the SPI is used in Slave mode with CKE

set, then the SS pin control must be

enabled.

SCK

(CKP = 1

SCK

(CKP = 0

Input

Sample

SDI

bit7

SDO

bit7

bit6

bit7

SSPIF

Interrupt

(SMP = 0)

CKE = 0)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

Flag

bit0

bit7

bit0

Next Q4 cycle

after Q2

↓

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式