MC9S12E256 Datasheet, PDF (248/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 8 Serial Communication Interface (SCIV4)
8.3.2.1 SCI Baud Rate Registers (SCIBDH and SCIBDL)
R
W
Reset
7
IREN
0
6
TNP1
5
TNP0
4
SBR12
3
SBR11
2
SBR10
0
0
0
0
0
Figure 8-3. SCI Baud Rate Register High (SCIBDH)
1
SBR9
0
0
SBR8
0
Table 8-1. SCIBDH Field Descriptions
Field
Description
7
IREN
Infrared Enable Bit — This bit enables/disables the infrared modulation/demodulation submodule.
0 IR disabled
1 IR enabled
6:5
Transmitter Narrow Pulse Bits — These bits determine if the SCI will transmit a 1/16, 3/16, 1/32, or 1/4 narrow
TNP[1:0] pulse. Refer to Table 8-3.
4:0
SBR[11:8]
SCI Baud Rate Bits — The baud rate for the SCI is determined by the bits in this register. The baud rate is
calculated two different ways depending on the state of the IREN bit.
The formulas for calculating the baud rate are:
When IREN = 0 then,
SCI baud rate = SCI module clock / (16 x SBR[12:0])
When IREN = 1 then,
SCI baud rate = SCI module clock / (32 x SBR[12:1])
R
W
Reset
7
SBR7
0
6
SBR6
5
SBR5
4
SBR4
3
SBR3
2
SBR2
0
0
0
0
1
Figure 8-4. SCI Baud Rate Register Low (SCIBDL)
1
SBR1
0
0
SBR0
0
Table 8-2. SCIBDL Field Descriptions
Field
7:0
SBR[7:0]
Description
SCI Baud Rate Bits — The baud rate for the SCI is determined by the bits in this register. The baud rate is
calculated two different ways depending on the state of the IREN bit.
The formulas for calculating the baud rate are:
When IREN = 0 then,
SCI baud rate = SCI module clock / (16 x SBR[12:0])
When IREN = 1 then,
SCI baud rate = SCI module clock / (32 x SBR[12:1])
MC9S12E256 Data Sheet, Rev. 1.08
248
Freescale Semiconductor