PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 144

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18FXX8
17.3.1
The MSSP module has four registers for SPI mode
operation. These are:
• MSSP Control Register1 (SSPCON1)
• MSSP Status Register (SSPSTAT)
• Serial Receive/Transmit Buffer (SSPBUF)
• MSSP Shift Register (SSPSR) - Not directly
SSPCON1 and SSPSTAT are the control and status
registers in SPI mode operation. The SSPCON1 regis-
ter is readable and writable. The lower 6 bits of the
SSPSTAT are read only. The upper two bits of the
SSPSTAT are read/write.
REGISTER 17-1:
DS41159B-page 142
accessible
REGISTERS
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
SSPSTAT: MSSP STATUS REGISTER (SPI MODE)
bit 7
SMP: Sample bit
SPI Master mode:
1 = Input data sampled at end of data output time
0 = Input data sampled at middle of data output time
SPI Slave mode:
SMP must be cleared when SPI is used in Slave mode
CKE: SPI Clock Edge Select
When CKP = 0:
1 = Data transmitted on rising edge of SCK
0 = Data transmitted on falling edge of SCK
When CKP = 1:
1 = Data transmitted on falling edge of SCK
0 = Data transmitted on rising edge of SCK
D/A: Data/Address bit
Used in I
P: STOP bit
Used in I
cleared.
S: START bit
Used in I
R/W: Read/Write bit information
Used in I
UA: Update Address
Used in I
BF: Buffer Full Status bit (Receive mode only)
1 = Receive complete, SSPBUF is full
0 = Receive not complete, SSPBUF is empty
Legend:
R = Readable bit
- n = Value at POR
R/W-0
SMP
2
2
2
2
2
C mode only
C mode only
C mode only
C mode only
C mode only. This bit is cleared when the MSSP module is disabled, SSPEN is
R/W-0
CKE
W = Writable bit
’1’ = Bit is set
Preliminary
R-0
D/A
R-0
SSPSR is the shift register used for shifting data in or
out. SSPBUF is the buffer register to which data bytes
are written to or read from.
In receive operations, SSPSR and SSPBUF together
create a double buffered receiver. When SSPSR
receives a complete byte, it is transferred to SSPBUF
and the SSPIF interrupt is set.
During transmission, the SSPBUF is not double buff-
ered. A write to SSPBUF will write to both SSPBUF and
SSPSR.
P
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared
R-0
S
R/W
R-0
 2002 Microchip Technology Inc.
x = Bit is unknown
R-0
UA
R-0
BF
bit 0