Datasheet
49.6.8 MCAN Nominal Bit Timing and Prescaler Register
Name: MCAN_NBTP
Offset: 0x1C
Reset: 0x06000A03
Property: Read/Write
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. t
q
= t
core 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] t
q
or (functional values) [Sync_Seg + Prop_Seg + Phase_Seg1 + Phase_Seg2] t
q
.
The Information Processing T
ime (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[24]
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
Bits 31:25 – NSJW[6:0] Nominal (Re) Synchronization Jump Width
0 to 127: The duration of a synchronization jump is t
q
x (NSJW + 1).
Bits 24:16 – NBRP[8:0]
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) = t
core clock
x (NBRP + 1)
Bits 15:8 – NTSEG1[7:0] Nominal Time Segment Before Sample Point
Value Description
0
Reserved; do not use.
1 to 255
The duration of time segment is t
q
x (NTSEG1 + 1).
Bits 6:0 – NTSEG2[6:0] Nominal T
ime Segment After Sample Point
Value Description
0
Reserved; do not use.
1 to 127
The duration of time segment is t
q
x (NTSEG2 + 1).
SAM E70/S70/V70/V71 Family
Controller Area Network (MCAN)
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 1444