PIC16LC74-20I/SP 查看數據表（PDF） - Microchip Technology

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PIC16LC74-20I/SP

8-Bit CMOS Microcontrollers with A/D Converter

Microchip Technology 

Applicable Devices

72 73 73A 74 74A 76 77

PIC16C7X

The SS pin allows a synchronous slave mode. The

SPI must be in slave mode (SSPCON<3:0> = 04h)

and the TRISA<5> bit must be set for the synchro-

nous slave mode to be enabled. 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. If the SS pin is taken low without resetting

SPI mode, the transmission will continue from the

point at which it was taken high. External pull-up/

pull-down resistors may be desirable, depending on the

application.

.

Note:

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.

Note:

If the SPI is used in Slave Mode with

CKE = '1', then the SS pin control must be

enabled.

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 11-11: SPI MODE TIMING, MASTER MODE (PIC16C76/77)

SCK (CKP = 0,

CKE = 0)

SCK (CKP = 0,

CKE = 1)

SCK (CKP = 1,

CKE = 0)

SCK (CKP = 1,

CKE = 1)

SDO

bit7

bit6

bit5

bit4

bit3

bit2

bit1

bit0

SDI (SMP = 0)

SDI (SMP = 1)

SSPIF

bit7

bit7

FIGURE 11-12: SPI MODE TIMING (SLAVE MODE WITH CKE = 0) (PIC16C76/77)

SS (optional)

bit0

bit0

SCK (CKP = 0)

SCK (CKP = 1)

SDO

SDI (SMP = 0)

SSPIF

bit7

bit6

bit5

bit4

bit3

bit2

bit1

bit0

bit7

bit0

© 1997 Microchip Technology Inc.

DS30390E-page 87

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