Freescale Semiconductor MPC5200B User Manual
Page 647
MPC5200B Users Guide, Rev. 1
19-8
Freescale Semiconductor
Memory Map / Register Definition
19.5.5
MSCAN Bus Timing Register 0 (CANBTR0)—MBAR + 0x0904 / 0x984
The MSCAN Bus Timing Register 0 provides for various bus timing control of the MSCAN module.
Read: Anytime
Write: Anytime in Initialization Mode (INITRQ = 1 and INITAK = 1)
6
SLPAK
Sleep Mode Acknowledge—flag indicates whether MSCAN module has entered sleep mode.
It is used as a handshake flag for SLPRQ sleep mode request. Sleep mode is active when
INITRQ=1 and INITAK=1. Depending on the WUPE bit setting, MSCAN clears the flag if it
detects bus activity on CAN while in Sleep Mode.
0 = Running—MSCAN operates normally
1 = Sleep Mode Active—MSCAN has entered Sleep Mode
7
INITAK
Initialization Mode Acknowledge—flag indicates whether MSCAN module is in initialization
mode. It is used as a handshake flag for the INITRQ initialization mode request. Initialization
mode is active when INITRQ=1 and INITAK=1. The registers CANCTL1, CANBTR0,
CANBTR1, CANIDAC, CANIDAR0-7, CANIDMR0-7 can only be written 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
Table 19-5. MSCAN Bus Timing Register 0
msb 0
1
2
3
4
5
6
7 lsb
R
SJW[1:0]
BRP[5:0]
W
RESET:
0
0
0
0
0
0
0
0
Bit
Name
Description
0:1
SJW[1:0]
Synchronization Jump Width—defines the maximum number of time quanta (Tq) clock
cycles a bit can be shortened or lengthened to achieve re-synchronization to data transitions
on the bus.
00 = 1 Tq clock cycle
01 = 2 Tq clock cycles
10 = 3 Tq clock cycles
11 = 4 Tq clock cycles
2:7
BRP[5:0]
Baud Rate Prescaler—bits determine time quanta (Tq) clock used to build up individual bit
timing, see
Table 19-6. Baud Rate Prescaler
BRP5
BRP4
BRP3
BRP2
BRP1
BRP0
Prescaler Value (P)
0
0
0
0
0
0
1
0
0
0
0
0
1
2
0
0
0
0
1
0
3
0
0
0
0
1
1
4
........................................................................................................................................
Bit
Name
Description