MC68HC08AS32 Datasheet, PDF (308/394 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Serial Peripheral Interface (SPI)
18.14.3 SPI Data Register
The SPI data register is the read/write buffer for the receive data register
and the 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 buffers that can contain different values. See
Figure 18-1.
Address: $0012
Bit 7
6
5
4
3
2
1
Bit 0
Read: R7
R6
R5
R4
R3
R2
R1
R0
Write: T7
T6
T5
T4
T3
T2
T1
T0
Reset:
Unaffected by Reset
Figure 18-14. SPI Data Register (SPDR)
R7–R0/T7–T0 — Receive/Transmit Data Bits
NOTE: Do not use read-modify-write instructions on the SPI data register since
the buffer read is not the same as the buffer written.
Advance Information
308
Serial Peripheral Interface (SPI)
MC68HC08AS32 — Rev. 3.0
MOTOROLA