mc68hc908jw32 Freescale Semiconductor, Inc, mc68hc908jw32 Datasheet - Page 143

• Manufacturer Part Number: mc68hc908jw32
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

SPR1 and SPR0 — SPI Baud Rate Select Bits
Use this formula to calculate the SPI baud rate:
where:
10.13.3 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
Freescale Semiconductor
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 clock generator module (CGM)
BD = baud rate divisor
Address:
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:
SPR1 and SPR0
$004E
Bit 7
R7
T7
00
01
10
11
Baud rate
Table 10-4. SPI Master Baud Rate Selection
Figure 10-15. SPI Data Register (SPDR)
R6
T6
6
MC68HC908JW32 Data Sheet, Rev. 5
=
CGMOUT
------------------------- -
2
R5
T5
5
×
BD
NOTE
Unaffected by reset
R4
T4
4
Baud Rate Divisor (BD)
Figure
R3
T3
3
128
32
10-2.)
2
8
R2
T2
2
R1
T1
1
Table
Bit 0
R0
T0
10-4. SPR1 and
I/O Registers
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