P16F877 datasheet(86/218 Pages) MICROCHIP

86 / 218 page

PIC16F87X

DS30292C-page 84

 2001 Microchip Technology Inc.

9.2.12

I2C MASTER MODE RECEPTION

Master mode reception is enabled by programming the

Receive Enable bit, RCEN (SSPCON2<3>).

The baud rate generator begins counting, and on each

rollover, the state of the SCL pin changes (high to low/

low to high), and data is shifted into the SSPSR. After

the falling edge of the eighth clock, the receive enable

flag is automatically cleared, the contents of the

SSPSR are loaded into the SSPBUF, the BF flag is set,

the SSPIF is set, and the baud rate generator is sus-

pended from counting, holding SCL low. The SSP is

now in IDLE state, awaiting the next command. When

the buffer is read by the CPU, the BF flag is automati-

cally cleared. The user can then send an Acknowledge

bit at the end of reception, by setting the Acknowledge

Sequence Enable bit, ACKEN (SSPCON2<4>).

9.2.12.1

BF Status Flag

In receive operation, BF is set when an address or data

byte is loaded into SSPBUF from SSPSR. It is cleared

when SSPBUF is read.

9.2.12.2

SSPOV Status Flag

In receive operation, SSPOV is set when 8 bits are

received into the SSPSR, and the BF flag is already set

from a previous reception.

9.2.12.3

WCOL Status Flag

If the user writes the SSPBUF when a receive is

already in progress (i.e., SSPSR is still shifting in a data

byte), then WCOL is set and the contents of the buffer

are unchanged (the write doesn’t occur).

Note:

The SSP module must be in an IDLE state

before the RCEN bit is set, or the RCEN bit

will be disregarded.

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