MC9S12KG128 Datasheet, PDF (329/600 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 10 Serial Communications Interface (SCIV1)
10.3.2.1 SCI Baud Rate Registers (SCIBDH and SCHBDL)
Module Base + 0x_0000
7
6
R
0
0
W
Reset
0
0
5
4
3
2
1
0
0
SBR12
SBR11
SBR10
SBR9
SBR8
0
0
0
0
0
0
Module Base + 0x_0001
R
W
Reset
7
SBR7
0
6
SBR6
5
SBR5
4
SBR4
3
SBR3
2
SBR2
1
SBR1
0
0
0
0
1
0
= Unimplemented or Reserved
Figure 10-3. SCI Baud Rate Registers (SCIBDH and SCIBDL)
0
SBR0
0
The SCI Baud Rate Register is used by the counter to determine the baud rate of the SCI. The formula for
calculating the baud rate is:
SCI baud rate = SCI module clock / (16 x BR)
where:
BR is the content of the SCI baud rate registers, bits SBR12 through SBR0. The baud rate registers
can contain a value from 1 to 8191.
Read: Anytime. If only SCIBDH is written to, a read will not return the correct data until SCIBDL is
written to as well, following a write to SCIBDH.
Write: Anytime
Table 10-1. SCIBDH AND SCIBDL Field Descriptions
Field
Description
4–0
7–0
SBR[12:0]
SCI Baud Rate Bits — The baud rate for the SCI is determined by these 13 bits.
Note: The baud rate generator is disabled until the TE bit or the RE bit is set for the first time after reset. The
baud rate generator is disabled when BR = 0.
Writing to SCIBDH has no effect without writing to SCIBDL, since writing to SCIBDH puts the data in a
temporary location until SCIBDL is written to.
MC9S12KG128 Data Sheet, Rev. 1.15
Freescale Semiconductor
329