MCAN Nominal Bit Timing and Prescaler Register
This register can only be written if the bits CCE and INIT are set in MCAN_CCCR.
The CAN bit time may be programmed in the range of 4 to 385 time quanta. The CAN time quantum may be programmed in the range of 1 to 512 CAN core clock periods. tq = tcore clock x (NBRP + 1).
NTSEG1 is the sum of Prop_Seg and Phase_Seg1. NTSEG2 is Phase_Seg2.
Therefore the length of the bit time is (programmed values) [NTSEG1 + NTSEG2 + 3] tq or (functional values) [Sync_Seg + Prop_Seg + Phase_Seg1 + Phase_Seg2] tq.
The Information Processing Time (IPT) is zero, meaning the data for the next bit is available at the first clock edge after the sample point.
With a CAN core clock frequency of 8 MHz, the reset value of 0x06000A03 configures the MCAN for a bit rate of 500 kbit/s.
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| NSJW[6:0] | NBRP[8] | ||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | |
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| NBRP[7:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| NTSEG1[7:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| NTSEG2[6:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | ||
| Reset | 0 | 0 | 0 | 0 | 0 | 1 | 1 | ||
Nominal Time Segment After Sample Point
| Value | Description |
|---|---|
| 0 |
Reserved; do not use. |
| 1 to 127 | The duration of time segment is tq x (NTSEG2 + 1). |
Nominal Time Segment Before Sample Point
| Value | Description |
|---|---|
| 0 | Reserved; do not use. |
| 1 to 255 | The duration of time segment is tq x (NTSEG1 + 1). |
Nominal Bit Rate Prescaler
0 to 511: The value by which the oscillator frequency is divided for generating the CAN time quanta. The CAN time is built up from a multiple of this quanta. CAN time quantum (tq) = tcore clock x (NBRP + 1)
Nominal (Re) Synchronization Jump Width
0 to 127: The duration of a synchronization jump is tq x (NSJW + 1).