Memory Map / Register Definition
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 19-9
19.5.6 MSCAN Bus Timing Register 1 (CANBTR1)—MBAR + 0x0905 / 0x985
The MSCAN Bus Timing Register 1 provides for various bus timing control of the MSCAN module.
Read: Anytime
Write: Anytime in Initialization Mode (INITRQ = 1 and INITAK = 1)
Read: Anytime
Write: Anytime in Initialization Mode (INITRQ = 1 and INITAK = 1)
Bit-time, as shown below, is determined by:
oscillator frequency
baud rate prescaler
number of time quanta (Tq) clock cycles per bit
Table19-8 and Table 19-9 give time segment values.
11111 0 63
11111 1 64

Table19-7. MSCAN Bus Timing Register 1

msb 01234567 lsb
R
SAMP
TSEG[22:20] TSEG[13:10]
W
RESET:00000000
Bit Name Description
0 SAMP Sampling—bit determines number of serial bus samples taken per bit-time. If set, three
samples per bit are taken; the regular one (sample point) and two preceding samples using
a majority rule. For higher bit-rates, it is recommended that SAMP be cleared, which
means only one sample is taken per bit.
0 = One sample per bit
1 = Three samples per bit
1:3 TSEG[ 22:20 ] Time Segment 2—time segments within the bit-time, fix the number of clock cycles per
bit-time and the location of the sample point. Time segment 2 (TSEG2) values are
programmable as shown in Table19-9.
4:7 TSEG[ 13:10 ] Time Segment 1—time segments within the bit-time, fix the number of clock cycles per
bit-time and the location of the sample point. Time segment 1 (TSEG1) values are
programmable as shown in Table19-8.

Table19-8. Time Segment 1 Values

TSEG13 TSEG12 TSEG11 TSEG10 Time segment 1
00001 Tq clock cycle ( a)
00012 Tq clock cycles ( 1)
00103 Tq clock cycles ( 1)

Table19-6. Baud Rate Prescaler (continued)

BRP5 BRP4 BRP3 BRP2 BRP1 BRP0 Prescaler Value (P )

Bit Time = (Prescaler value)

(Number of Time Quanta)

fCANCLK