PIC16C63A Microchip Technology, PIC16C63A Datasheet - Page 56

• Manufacturer Part Number: PIC16C63A
• Description: 28/40-Pin 8-Bit CMOS Microcontrollers
• Manufacturer: Microchip Technology

PIC16C63A/65B/73B/74B
8.3
The SSP module in I
functions, except general call support, and provides
interrupts on start and stop bits in hardware to facilitate
firmware implementations of the master functions. The
SSP module implements the standard mode specifica-
tions as well as 7-bit and 10-bit addressing.
Two pins are used for data transfer. These are the RC3/
SCK/SCL pin, which is the clock (SCL), and the RC4/
SDI/SDA pin, which is the data (SDA). The user must
configure these pins as inputs or outputs through the
TRISC<4:3> bits.
The SSP module functions are enabled by setting SSP
Enable bit SSPEN (SSPCON<5>).
FIGURE 8-4:
The SSP module has five registers for I
These are the:
• SSP Control Register (SSPCON)
• SSP Status Register (SSPSTAT)
• Serial Receive/Transmit Buffer (SSPBUF)
• SSP Shift Register (SSPSR) - Not directly acces-
• SSP Address Register (SSPADD)
DS30605A-page 56
RC3/SCK/SCL
RC4/
sible
SDA
SDI/
SSP I
2
Read
clock
shift
C Operation
SSP BLOCK DIAGRAM
(I
2
MSb
2
C MODE)
C mode fully implements all slave
Stop bit detect
Match detect
SSPADD reg
SSPBUF reg
SSPSR reg
Start and
LSb
Write
(SSPSTAT reg)
data bus
2
Internal
C operation.
Set, Reset
S, P bits
Addr Match
The SSPCON register allows control of the I
tion. Four mode selection bits (SSPCON<3:0>) allow
one of the following I
• I
• I
• I
• I
• I
Selection of any I
forces the SCL and SDA pins to be open drain, pro-
vided these pins are programmed to inputs by setting
the appropriate TRISC bits.
Additional information on SSP I
found in the PICMicro
(DS33023).
8.3.1
In slave mode, the SCL and SDA pins must be config-
ured as inputs (TRISC<4:3> set). The SSP module will
override the input state with the output data when
required (slave-transmitter).
When an address is matched or the data transfer after
an address match is received, the hardware automati-
cally will generate the acknowledge (ACK) pulse, and
then load the SSPBUF register with the received value
currently in the SSPSR register.
There are certain conditions that will cause the SSP
module not to give this ACK pulse. These are if either
(or both):
a)
b)
In this case, the SSPSR register value is not loaded
into the SSPBUF, but bit SSPIF (PIR1<3>) is set.
Table 8-2 shows what happens when a data transfer
byte is received, given the status of bits BF and
SSPOV. The shaded cells show the condition where
user software did not properly clear the overflow condi-
tion. Flag bit BF is cleared by reading the SSPBUF reg-
ister while bit SSPOV is cleared through software.
The SCL clock input must have a minimum high and
low for proper operation. The high and low times of the
I
module is shown in timing parameter #100 and param-
eter #101.
2
C specification as well as the requirement of the SSP
stop bit interrupts enabled
stop bit interrupts enabled
is idle
2
2
2
2
2
C Slave mode (7-bit address)
C Slave mode (10-bit address)
C Slave mode (7-bit address), with start and
C Slave mode (10-bit address), with start and
C Firmware controlled master operation, slave
The buffer full bit BF (SSPSTAT<0>) was set
before the transfer was received.
The overflow bit SSPOV (SSPCON<6>) was set
before the transfer was received.
SLAVE MODE
2
C mode, with the SSPEN bit set,
2
C modes to be selected:
Mid-Range Reference Manual
1998 Microchip Technology Inc.
2
C operation may be
2
C opera-