PIC16F87X Datasheet, PDF(111/218 Page) Microchip Technology – 28/40-pin 8-Bit CMOS FLASH Microcontrollers

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PIC16F87X Datasheet, PDF (111/218 Pages) Microchip Technology – 28/40-pin 8-Bit CMOS FLASH Microcontrollers

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PIC16F87X

10.4.2 USART SYNCHRONOUS SLAVE

RECEPTION

The operation of the Synchronous Master and Slave

modes is identical, except in the case of the SLEEP

mode. Bit SREN is a âdon't careâ in Slave mode.

If receive is enabled by setting bit CREN prior to the

SLEEP instruction, then a word may be received during

SLEEP. On completely receiving the word, the RSR

and if enable bit RCIE bit is set, the interrupt generated

will wake the chip from SLEEP. If the global interrupt is

enabled, the program will branch to the interrupt vector

(0004h).

When setting up a Synchronous Slave Reception, fol-

low these steps:

1. Enable the synchronous master serial port by

setting bits SYNC and SPEN and clearing bit

CSRC.

2. If interrupts are desired, set enable bit RCIE.

3. If 9-bit reception is desired, set bit RX9.

4. To enable reception, set enable bit CREN.

5. Flag bit RCIF will be set when reception is com-

plete and an interrupt will be generated, if

enable bit RCIE was set.

6. Read the RCSTA register to get the ninth bit (if

enabled) and determine if any error occurred

during reception.

7. Read the 8-bit received data by reading the

RCREG register.

8. If any error occurred, clear the error by clearing

bit CREN.

9. If using interrupts, ensure that GIE and PEIE

(bits 7 and 6) of the INTCON register are set.

TABLE 10-11: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION

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

10Bh,18Bh

0Ch

PIR1

GIE

PSPIF(1)

PEIE

ADIF

T0IE

RCIF

INTE

TXIF

RBIE T0IF INTF R0IF 0000 000x 0000 000u

SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000

18h

RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 0000 000x

1Ah

RCREG USART Receive Register

0000 0000 0000 0000

8Ch

PIE1

PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000

98h

TXSTA CSRC TX9 TXEN SYNC â

BRGH TRMT TX9D 0000 -010 0000 -010

99h

SPBRG Baud Rate Generator Register

0000 0000 0000 0000

Legend: x = unknown, - = unimplemented, read as '0'. Shaded cells are not used for synchronous slave reception.

Note 1: Bits PSPIE and PSPIF are reserved on PIC16F873/876 devices, always maintain these bits clear.

DS30292C-page 109

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