MC68HC908GZ8 Datasheet, PDF (297/344 Pages) Motorola, Inc – Microcontrollers

Serial Peripheral Interface (SPI) Module
I/O Registers
21.13.3 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 21-2.
Address: $0012
Bit 7
6
Read: R7
R6
Write: T7
T6
Reset:
5
4
3
2
R5
R4
R3
R2
T5
T4
T3
T2
Unaffected by reset
1
Bit 0
R1
R0
T1
T0
Figure 21-15. SPI Data Register (SPDR)
NOTE:
R7–R0/T7–T0 — Receive/Transmit Data Bits
Do not use read-modify-write instructions on the SPI data register since the register
read is not the same as the register written.
MC68HC908GZ8
Freescale Semiconductor
Serial Peripheral Interface (SPI) Module
Data Sheet
297