Serial Peripheral Interface (SPI)
SPI Registers
M68HC11K Family
Technical Data
MOTOROLA
Serial Peripheral Interface (SPI)
177
8.6.3 Serial Peripheral Data Register
The SPDR is used when transmitting or receiving data on the serial bus.
Only a write to this register initiates transmission or reception of a byte,
and this only occurs in the master device. At the completion of
transferring a byte of data, the SPIF status bit is set in both the master
and slave devices.
A read of the SPDR is actually a read of a buffer. To prevent an overrun
and the loss of the byte that caused the overrun, the first SPIF must be
cleared by the time a second transfer of data from the shift register to the
read buffer is initiated.
A write to SPDR goes directly to the transmission shift register.
A read of the SPDR retrieves data from the read data buffer.
Address: $002A
Bit 7
6
54321
Bit 0
Read:
Bit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
Write:
Reset:
00
000000
Figure 8-5. Serial Peripheral Data Register (SPDR)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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