PIC18F23K20-E/MLQTP MICROCHIP [Microchip Technology], PIC18F23K20-E/MLQTP Datasheet - Page 211

• Manufacturer Part Number: PIC18F23K20-E/MLQTP
• Description: 28/40/44-Pin Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

17.4.5
The addressing procedure for the I
the first byte after the Start condition usually
determines 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
GCEN bit of the SSPCON2 is set. Following a Start bit
detect, 8 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 hard-
ware.
FIGURE 17-15:
© 2007 Microchip Technology Inc.
GCEN (SSPCON2<7>)
SSPOV (SSPCON1<6>)
SDA
SCL
SSPIF
BF (SSPSTAT<0>)
GENERAL CALL ADDRESS
SUPPORT
S
SLAVE MODE GENERAL CALL ADDRESS SEQUENCE
(7 OR 10-BIT ADDRESS MODE)
1
2
General Call Address
2
C bus is such that
3
2
4
C protocol. It
Advance Information
5
6
7
R/W =
8
0
If the general call address matches, the SSPSR is
transferred to the SSPBUF, the BF flag 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
interrupt 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 of the SSPSTAT register is set. If the general call
address is sampled when the GCEN bit is set, 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 17-15).
PIC18F2XK20/4XK20
ACK
Address is compared to General Call Address
after ACK, set interrupt
9
D7
1
D6
2
Cleared by software
SSPBUF is read
Receiving Data
D5
3
D4
4
D3
5
D2
6
D1
7
DS41303B-page 209
D0
8
ACK
9
‘0’
‘1’