mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 224

• Manufacturer Part Number: mc68hc908gr8vp
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface (SPI)
SPR1 and SPR0 — SPI Baud Rate Select Bits
Use this formula to calculate the SPI baud rate:
where:
20.13.3 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
R7–R0/T7–T0 — Receive/Transmit Data Bits
224
In master mode, these read/write bits select one of four baud rates as shown in
SPR0 have no effect in slave mode. Reset clears SPR1 and SPR0.
BD = baud rate divisor
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
SPR1 and SPR0
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
Table 20-4. SPI Master Baud Rate Selection
Figure 20-15. SPI Data Register (SPDR)
R6
T6
00
01
10
11
6
R5
T5
5
Indeterminate after reset
NOTE
R4
T4
4
Baud Rate Divisor (BD)
Figure
R3
T3
3
128
32
20-2.
2
8
R2
T2
2
R1
T1
1
Table
Freescale Semiconductor
Bit 0
R0
T0
20-4. SPR1 and