mc9s12xs128 Freescale Semiconductor, Inc, mc9s12xs128 Datasheet - Page 305

• Manufacturer Part Number: mc9s12xs128
• Description: Hcs12 Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

11.3.2.3
The CANBTR0 register configures various CAN bus timing parameters of the MSCAN module.
1. Read: Anytime
Freescale Semiconductor
Module Base + 0x0002
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
SJW[1:0]
BRP[5:0]
SLPAK
INITAK
Field
Field
7-6
5-0
1
0
Reset:
W
R
Sleep Mode Acknowledge — This flag indicates whether the MSCAN module has entered sleep mode (see
Section 11.4.5.5, “MSCAN Sleep
Sleep mode is active when SLPRQ = 1 and SLPAK = 1. Depending on the setting of WUPE, the MSCAN will
clear the flag if it detects activity on the CAN bus while in sleep mode.
0 Running — The MSCAN operates normally
1 Sleep mode active — The MSCAN has entered sleep mode
Initialization Mode Acknowledge — This flag indicates whether the MSCAN module is in initialization mode
(see
mode request. Initialization mode is active when INITRQ = 1 and INITAK = 1. The registers CANCTL1,
CANBTR0, CANBTR1, CANIDAC, CANIDAR0–CANIDAR7, and CANIDMR0–CANIDMR7 can be written only by
the CPU when the MSCAN is in initialization mode.
0 Running — The MSCAN operates normally
1 Initialization mode active — The MSCAN has entered initialization mode
Synchronization Jump Width — The synchronization jump width defines the maximum number of time quanta
(Tq) clock cycles a bit can be shortened or lengthened to achieve resynchronization to data transitions on the
CAN bus (see
Baud Rate Prescaler — These bits determine the time quanta (Tq) clock which is used to build up the bit timing
(see
MSCAN Bus Timing Register 0 (CANBTR0)
SJW1
Section 11.4.4.5, “MSCAN Initialization
Table
0
7
11-7).
Table 11-4. CANCTL1 Register Field Descriptions (continued)
Table
Figure 11-6. MSCAN Bus Timing Register 0 (CANBTR0)
SJW1
SJW0
Table 11-5. CANBTR0 Register Field Descriptions
0
0
1
1
6
0
11-6).
Table 11-6. Synchronization Jump Width
S12XS Family Reference Manual Rev. 1.10
BRP5
0
Mode”). It is used as a handshake flag for the SLPRQ sleep mode request.
5
Mode”). It is used as a handshake flag for the INITRQ initialization
BRP4
SJW0
4
0
0
1
0
1
Description
Description
Freescale’s Scalable Controller Area Network (S12MSCANV3)
BRP3
0
3
Synchronization Jump Width
BRP2
2 Tq clock cycles
3 Tq clock cycles
4 Tq clock cycles
2
0
1 Tq clock cycle
Access: User read/write
BRP1
0
1
BRP0
0
0
305
(1)