MC68HC711PH8 Motorola, MC68HC711PH8 Datasheet - Page 98

• Manufacturer Part Number: MC68HC711PH8
• Description: High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit
• Manufacturer: Motorola

5
5.6.1
The contents of this register determine the baud rate of the SCI.
BTST — Baud register test (Test mode only)
BSPL — Baud rate counter split (Test mode only)
BRST — Baud rate reset (Test mode only)
SBR[12:0] — SCI baud rate selects
Use the following formula to calculate SCI baud rate. Refer to the table of baud rate control values
for example rates:
where the baud rate control value (BR) is the contents of SCBDH/L (BR = 1, 2, 3,... 8191).
For example, to obtain a baud rate of 1200 with a ST4XCK frequency of 12MHz, the baud register
(SCBDH/L) should contain $0138 (see Table 5-1).
The clock rate generator is disabled if BR = 0, or if neither the receiver nor transmitter is enabled
(both RE and TE in SCCR2 are cleared).
Writes to the baud rate registers will only be successful if the last (or only) byte written is SCBDL.
The use of an STD instruction is recommended as it guarantees that the bytes are written in the
correct order.
Note:
MOTOROLA
5-6
SCI1 baud rate high (SCBDH)
SCI1 baud rate low (SCBDL)
ST4XCK may be the output of the PLL circuit or it may be the EXTAL input of the MCU
(see Section 2.5, Figure 8-1 and Figure 8-2).
SCBDH, SCBDL — SCI baud rate control registers
SERIAL COMMUNICATIONS INTERFACE
Address
$0070
$0071
SCI baud rate
SBR7 SBR6 SBR5 SBR4 SBR3 SBR2 SBR1 SBR0 0000 0100
BTST
bit 7
BSPL BRST SBR12 SBR11 SBR10 SBR9 SBR8 0000 0000
bit 6
=
bit 5
---------------------------- -
16
ST 4 XCK
2 BR
bit 4
bit 3
bit 2
bit 1
MC68HC11PH8
bit 0
on reset
State
TPG