MC912DG128A Motorola, MC912DG128A Datasheet - Page 244

• Manufacturer Part Number: MC912DG128A
• Description: Microcontrollers
• Manufacturer: Motorola

SP0DR — SPI Data Register
Multiple Serial Interface
MC68HC912DT128A Rev 2.0
244
Bit 7
Bit 7
6
6
WCOL — Write Collision Status Flag
MODF — SPI Mode Error Interrupt Status Flag
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
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 register is serially
shifted eight bit positions by the SCK clock from the master so the data
is effectively exchanged between the master and the slave. Note that
The MCU write is disabled to avoid writing over the data being
transferred. No interrupt is generated because the error status flag
can be read upon completion of the transfer that was in progress at
the 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.
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.
0 = No write collision
1 = Indicates that a serial transfer was in progress when the MCU
5
5
tried to write new data into the SP0DR data register.
Multiple Serial Interface
4
4
3
3
2
2
1
1
Bit 0
Bit 0
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