PIC16F883 Microchip Technology Inc., PIC16F883 Datasheet - Page 190

• Manufacturer Part Number: PIC16F883
• Description: 28/40/44-pin Flash-based, 8-bit Cmos Microcontrollers With Nanowatt Technology
• Manufacturer: Microchip Technology Inc.

PIC16F882/883/884/886/887
13.4.2
The addressing procedure for the I
the first byte after the Start condition usually deter-
mines which device will be the slave addressed by the
master. The exception is the general call address,
which can address all devices. When this address is
used, all devices should, in theory, respond with an
Acknowledge.
The general call address is one of eight addresses
reserved for specific purposes by the I
consists of all 0’s with R/W = 0.
The general call address is recognized (enabled) when
the General Call Enable (GCEN) bit is set (SSPCON2
register). Following a Start bit detect, eight bits are
shifted into the SSPSR and the address is compared
against the SSPADD. It is also compared to the general
call address and fixed in hardware.
FIGURE 13-9:
DS41291D-page 188
GCEN
SSPOV
SDA
SCL
SSPIF
BF
GENERAL CALL ADDRESS
SUPPORT
S
SLAVE MODE GENERAL CALL ADDRESS SEQUENCE (7 OR 10-BIT ADDRESS)
1
2
General Call Address
2
C bus is such that,
3
2
C protocol. It
4
5
6
Preliminary
7
R/W = 0
8
If the general call address matches, the SSPSR is
transferred to the SSPBUF, the BF bit is set (eighth bit),
and on the falling edge of the ninth bit (ACK bit), the
SSPIF interrupt flag bit is set.
When the interrupt is serviced, the source for the inter-
rupt can be checked by reading the contents of the
SSPBUF. The value can be used to determine if the
address was device specific or a general call address.
In 10-bit mode, the SSPADD is required to be updated
for the second half of the address to match, and the UA
bit is set (SSPSTAT register). If the general call address
is sampled when the GCEN bit is set, and while the
slave is configured in 10-bit address mode, then the
second half of the address is not necessary. The UA bit
will not be set, and the slave will begin receiving data
after the Acknowledge (Figure 13-9).
ACK
Address is compared to General Call Address
after ACK, set interrupt
9
D7
1
D6
2
Cleared in software
SSPBUF is read
Receiving Data
D5
3
D4
4
© 2007 Microchip Technology Inc.
D3
5
D2
6
D1
7
D0
8
ACK
9
‘0’
‘1’