Serial Peripheral Interface Module (SPI)
I/O Registers
MC68HC908AB32 — Rev. 1.0 Technical Data
MOTOROLA Serial Peripheral Interface Module (SPI) 309
16.14.3 SPI Data Register
The SPI data register consists of the read-only receive data register and
the write-only transmit data register. Writing to the SPI data register
writes data into the transmit data register. Reading the SPI data register
reads data from the receive data register. The transmit data and receive
data registers are separate registers that can contain different values.
(See Figure 16-2.)
R7–R0/T7–T0 — Receive/Transmit Data Bits
NOTE:
Do not use read-modify-write instructions on the SPI data register since
the register read is not the same as the register written.
Address: $0012
Bit 7 654321Bit 0
Read: R7 R6 R5 R4 R3 R2 R1 R0
Write: T7 T6 T5 T4 T3 T2 T1 T0
Reset: Unaffected by reset
Figure 16-15. SPI Data Register (SPDR)
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