mc68hc908gr8b Freescale Semiconductor, Inc, mc68hc908gr8b Datasheet - Page 192

• Manufacturer Part Number: mc68hc908gr8b
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface (SPI) Module
15.12.3 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
R7–R0/T7–T0 — Receive/Transmit Data Bits
192
Use this formula to calculate the SPI baud rate:
Baud rate =
Address: $0012
Do not use read-modify-write instructions on the SPI data register since the
register read is not the same as the register written.
Reset:
Read:
Write:
BUSCLK
Bit 7
R7
T7
BD
Figure 15-16. SPI Data Register (SPDR)
R6
T6
6
MC68HC908GR8B Data Sheet, Rev. 3.0
R5
T5
5
NOTE
Unaffected by reset
R4
T4
4
Figure
R3
T3
3
15-2.
R2
T2
2
R1
T1
1
Freescale Semiconductor
Bit 0
R0
T0