MC68HC708MP16 Datasheet, PDF (282/398 Pages) Freescale Semiconductor, Inc – Microcontrollers

Serial Peripheral Interface Module (SPI)
13.14.3 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 13-1.)
Address: $001D
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:
Indeterminate after reset
Figure 13-15. 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 register read is not the same as the register written.
Technical Data
282
Serial Peripheral Interface Module (SPI)
MC68HC708MP16 — Rev. 3.1
Freescale Semiconductor