MC68HC912BL16 Datasheet, PDF (100/128 Pages) Freescale Semiconductor, Inc – 16-Bit Microcontroller

Freescale Semiconductor, Inc.
time of the error. Automatically cleared by a read of the SP0SR (with WCOL set) followed by an access
(read or write) to the SP0DR register.
0 = No write collision
1 = Indicates that a serial transfer was in progress when the MCU tried to write new data into the
SP0DR data register.
MODF — SPI Mode Error Interrupt Status Flag
This bit is set automatically by SPI hardware if the MSTR control bit is set and the slave select input pin
becomes zero. This condition is not permitted in normal operation. In the case where DDRS bit 7 is set,
the PS7 pin is a general-purpose output pin or SS output pin rather than being dedicated as the SS input
for the SPI system. In this special case the mode fault function is inhibited and MODF remains cleared.
This flag is automatically cleared by a read of the SP0SR (with MODF set) followed by a write to the
SP0CR1 register.
SP0DR — SPI Data Register
$00D5
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
RESET:
0
0
0
0
0
0
0
0
Read anytime (normally only after SPIF flag set). Write anytime (see WCOL write collision flag).
Reset does not affect this address.
This 8-bit register is both the input and output register for SPI data. Reads of this register are double
buffered but writes cause data to be written directly into the serial shifter. In the SPI system the 8-bit
data register in the master and the 8-bit data register in the slave are linked by the MOSI and MISO
wires to form a distributed 16-bit register. When a data transfer operation is performed, this 16-bit reg-
ister is serially shifted eight bit positions by the SCK clock from the master so the data is effectively ex-
changed between the master and the slave. Note that some slave devices are very simple and either
accept data from the master without returning data to the master or pass data to the master without re-
quiring data from the master.
13.4 Port S
In all modes, port S bits PS[7:4] and PS[1:0] can be used for either general-purpose I/O, or with the SCI
and SPI subsystems. During reset, port S pins are configured as high-impedance inputs (DDRS is
cleared).
PORTS — Port S Data Register
$00D6
Bit 7
6
5
4
3
2
1
Bit 0
PS7
PS6
PS5
PS4
PS3
PS2
PS1
PS0
Pin
SS
Function
CS
SCK
MOSI
MOMI
MISO
SISO
N/A
N/A
TXD0
RXD0
PORTS can be read anytime. When configured as an input, a read will return the pin level. When con-
figured as output, a read will return the latched output data. Writes do not change pin state when pin
configured for SPI or SCI output.
After reset all bits are configured as general-purpose inputs.
Port S shares function with the on-chip serial systems (SPI0 and SCI0).
DDRS — Data Direction Register for Port S
$00D7
Bit 7
6
5
4
3
2
1
Bit 0
DDS7 DDS6 DDS5 DDS4 DDS3 DDS2 DDS1 DDS0
RESET:
0
0
0
0
0
0
0
0
Read or write anytime.
After reset, all general-purpose I/O are configured for input only.
MC68HC912BL16
100
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