s908ey8ad4cfjer Freescale Semiconductor, Inc, s908ey8ad4cfjer Datasheet - Page 188

• Manufacturer Part Number: s908ey8ad4cfjer
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Serial Peripheral Interface (SPI) Module
SPR1 and SPR0 — SPI Baud Rate Select Bits
Use this formula to calculate the SPI baud rate:
where:
15.13.3 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
R7–R0/T7–T0 — Receive/Transmit Data Bits
188
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.
CGMOUT = base clock output of the internal clock generator module (ICG),
BD = baud rate divisor
Address:
Do not use read-modify-write instructions on the SPI data register since the
buffer read is not the same as the buffer written.
see
Reset:
Read:
Write:
Chapter 8 Internal Clock Generator (ICG)
$000F
Bit 7
R7
T7
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
SPR1:SPR0
Table 15-5. SPI Master Baud Rate Selection
Figure 15-14. SPI Data Register (SPDR)
00
01
10
11
R6
T6
6
Baud rate
R5
T5
5
Figure 15-2
=
Indeterminate after Reset
CGMOUT
------------------------- -
NOTE
2
R4
T4
4
×
Baud Rate Divisor (BD)
BD
R3
T3
3
128
32
Module.
2
8
R2
T2
2
R1
T1
1
Table
Freescale Semiconductor
Bit 0
R0
T0
15-5. SPR1 and