
Serial Peripheral Interface (SPI)
SPI Registers
MC68HC11E Family
—
Rev. 4
Technical Data
MOTOROLA
Serial Peripheral Interface (SPI)
173
8.8.1 Serial Peripheral Control Register
SPIE
—
Serial Peripheral Interrupt Enable Bit
Set the SPE bit to 1 to request a hardware interrupt sequence each
time the SPIF or MODF status flag is set. SPI interrupts are inhibited
if this bit is clear or if the I bit in the condition code register is 1.
0 = SPI system interrupts disabled
1 = SPI system interrupts enabled
SPE
—
Serial Peripheral System Enable Bit
When the SPE bit is set, the port D bit 2, 3, 4, and 5 pins are dedicated
to the SPI function. If the SPI is in the master mode and DDRD bit 5
is set, then the port D bit 5 pin becomes a general-purpose output
instead of the SS input.
0 = SPI system disabled
1 = SPI system enabled
DWOM
—
Port D Wired-OR Mode Bit
DWOM affects all port D pins.
0 = Normal CMOS outputs
1 = Open-drain outputs
MSTR
—
Master Mode Select Bit
It is customary to have an external pullup resistor on lines that are
driven by open-drain devices.
0 = Slave mode
1 = Master mode
Address:
$1028
Bit 7
6
5
4
3
2
1
Bit 0
Read:
SPIE
SPE
DWOM
MSTR
CPOL
CPHA
SPR1
SPR0
Write:
Reset:
0
0
0
0
0
1
U
U
U = Unaffected
Figure 8-3. Serial Peripheral Control Register (SPCR)