PIC16C923-04I/CL Microchip Technology, PIC16C923-04I/CL Datasheet - Page 76

• Manufacturer Part Number: PIC16C923-04I/CL
• Description: 8-Bit CMOS Microcontroller with LCD Driver
• Manufacturer: Microchip Technology

PIC16C9XX
11.3.1.3
When the R/W bit of the incoming address byte is set
and an address match occurs, the R/W bit of the
SSPSTAT register is set. The received address is
loaded into the SSPBUF register. The ACK pulse will be
sent on the ninth bit, and pin RC3/SCK/SCL is held low.
The transmit data must be loaded into the SSPBUF
register, which also loads the SSPSR register. Then pin
RC3/SCK/SCL should be enabled by setting bit CKP
(SSPCON<4>). The master must monitor the SCL pin
prior to asserting another clock pulse. The slave
devices may be holding off the master by stretching the
clock. The eight data bits are shifted out on the falling
edge of the SCL input. This ensures that the SDA signal
is valid during the SCL high time (Figure 11-20).
FIGURE 11-20: I
DS30444E - page 76
SDA
SCL
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
CKP (SSPCON<4>)
S
TRANSMISSION
A7
1
Data in
sampled
2
C WAVEFORMS FOR TRANSMISSION (7-BIT ADDRESS)
A6
2
A5
Receiving Address
3
A4
4
A3
5
A2
6
A1
7
R/W = 1
8
9
ACK
responds to SSPIF
SCL held low
while CPU
An SSP interrupt is generated for each data transfer
byte. Flag bit SSPIF must be cleared in software, and
the SSPSTAT register is used to determine the status of
the byte. Flag bit SSPIF is set on the falling edge of the
ninth clock pulse.
As a slave-transmitter, the ACK pulse from the mas-
ter-receiver is latched on the rising edge of the ninth
SCL input pulse. If the SDA line was high (not ACK),
then the data transfer is complete. When the ACK is
latched by the slave, the slave logic is reset and the
slave then monitors for another occurrence of the
START bit. If the SDA line was low (ACK), the transmit
data must be loaded into the SSPBUF register, which
also
RC3/SCK/SCL should be enabled by setting bit CKP.
D7
1
SSPBUF is written in software
loads
D6
2
Set bit after writing to SSPBUF
(the SSPBUF must be written-to
before the CKP bit can be set)
cleared in software
D5
3
the
D4
4
SSPSR
Transmitting Data
D3
5
1997 Microchip Technology Inc.
D2
6
From SSP interrupt
service routine
D1
7
register.
D0
8
ACK
9
Then
P
pin