PIC16F74-I/P Microchip Technology Inc., PIC16F74-I/P Datasheet - Page 69

• Manufacturer Part Number: PIC16F74-I/P
• Description: 40 PIN, 7 KB FLASH, 192 RAM, 33 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F74-I/P

• A/d Inputs: 8-Channel, 8-Bit
• Cpu Speed: 5 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 33
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 7K Bytes
• Ram Size: 192 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

FIGURE 9-6:
9.3.1.3
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 regis-
ter. Then, pin RC3/SCK/SCL should be enabled by set-
ting 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 stretch-
ing 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 9-7).
FIGURE 9-7:
 2002 Microchip Technology Inc.
SDA
SCL
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
CKP (SSPCON<4>)
SDA
SCL
SSPIF (PIR1<3>)
BF (SSPSTAT<0>)
SSPOV (SSPCON<6>)
S
S
A7 A6 A5 A4 A3 A2 A1
1
Transmission
A7
2
1
Data in
sampled
Receiving Address
3
A6
2
I
I
4
2
2
C WAVEFORMS FOR TRANSMISSION (7-BIT ADDRESS)
C WAVEFORMS FOR RECEPTION (7-BIT ADDRESS)
A5
Receiving Address
3
5
A4
4
6
7
A3
R/W=0
5
8
A2
6
ACK
9
A1
7
D7
1
R/W = 1
D6
2
8
SSPBUF register is read
Receiving Data
D5
3
Cleared in software
9
ACK
D4
Bit SSPOV is set because the SSPBUF register is still full.
responds to SSPIF
4
SCL held low
while CPU
D3
5
D2
6
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 master-
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 (resets SSPSTAT
register) and the slave then monitors for another occur-
rence of the START bit. If the SDA line was low (ACK),
the transmit data must be loaded into the SSPBUF reg-
ister, which also loads the SSPSR register. Then pin
RC3/SCK/SCL should be enabled by setting bit CKP.
D1
7
D7
D0
1
SSPBUF is written in software
8
ACK
9
D6
2
Cleared in software
Set bit after writing to SSPBUF
(the SSPBUF must be written to
before the CKP bit can be set)
D7
1
D5
3
D6
2
D4
4
D5
Receiving Data
3
Transmitting Data
D3
D4
4
5
ACK is not sent.
D3
5
D2
6
PIC16F7X
D2
6
From SSP Interrupt
Service Routine
D1
7
D1
7
D0
8
D0
DS30325B-page 67
8
ACK
ACK
9
9
Bus Master
terminates
transfer
P
P