PIC16C770 Microchip Technology Inc., PIC16C770 Datasheet - Page 84

• Manufacturer Part Number: PIC16C770
• Description: 18/20-pin, 8-bit Cmos Microcontrollers With 10/12-bit A/d
• Manufacturer: Microchip Technology Inc.

PIC16C717/770/771
9.2.3
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 when the Gen-
eral Call Enable bit (GCEN) is set (SSPCON2<7> is
set). Following a START bit detect, eight bits are shifted
FIGURE 9-12:
DS41120B-page 82
GCEN
(SSPCON2<7>)
SSPOV
(SSPCON<6>)
SDA
SCL
SSPIF
BF
(SSPSTAT<0>)
GENERAL CALL ADDRESS
SUPPORT
S
SLAVE MODE GENERAL CALL ADDRESS SEQUENCE (7- OR 10-BIT MODE)
1
2
General Call Address
2
C bus is such that
3
2
C protocol. It
4
Advance Information
5
6
7
R/W = 0
8
into the SSPSR, and the address is compared against
SSPADD. It is also compared to the general call
address, fixed in hardware.
If the general call address matches, the SSPSR is
transferred to the SSPBUF, the BF flag is set (eighth
bit), and on the falling edge of the ninth bit (ACK bit),
the SSPIF flag is set.
When the interrupt is serviced, the source for the inter-
rupt can be checked by reading the contents of the
SSPBUF to determine if the address was device spe-
cific or a general call address.
If the general call address is sampled with GCEN set
and the slave configured in 10-bit Address mode, 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 9-12).
ACK
Address is compared to General Call Address
after ACK, set interrupt flag
9
D7
1
D6
2
Cleared in software
SSPBUF is read
Receiving data
D5
3
D4
4
D3
5
2002 Microchip Technology Inc.
D2
6
D1
7
D0
8
ACK
9
’0’
’1’