Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller SOIC 28 8-Bit 4 MHz I/O number 22

PIC16C7X

DS30390E-page 82  1997 Microchip Technology Inc.

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 the for 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.

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 11-5: SPI MODE TIMING, MASTER MODE OR SLAVE MODE W/O SS CONTROL

FIGURE 11-6: SPI MODE TIMING, SLAVE MODE WITH SS CONTROL

TABLE 11-1: REGISTERS ASSOCIATED WITH SPI OPERATION

Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Value on:

POR,

BOR

Value on

all other

resets

0Bh,8Bh INTCON GIE PEIE

T0IE INTE RBIE T0IF INTF RBIF 0000 000x 0000 000u

0Ch PIR1 PSPIF

(1,2)

ADIF RCIF

(2)

TXIF

(2)

SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

8Ch PIE1 PSPIE

(1,2)

ADIE RCIE

(2)

TXIE

(2)

SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

87h TRISC PORTC Data Direction Register 1111 1111 1111 1111

13h SSPBUF Synchronous Serial Port Receive Buffer/Transmit Register xxxx xxxx uuuu uuuu

14h SSPCON WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 0000 0000

85h TRISA — — PORTA Data Direction Register --11 1111 --11 1111

94h SSPSTAT — — D/A P S R/W UA BF --00 0000 --00 0000

Legend: x = unknown, u = unchanged, - = unimplemented read as '0'. Shaded cells are not used by the SSP in SPI mode.

Note 1: Bits PSPIE and PSPIF are reserved on the PIC16C73/73A, always maintain these bits clear.

2: The PIC16C72 does not have a Parallel Slave Port or USART, these bits are unimplemented, read as '0'.

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

SSPIF

bit7

bit7 bit0

bit6 bit5 bit4 bit3 bit2 bit1 bit0

SCK