38.8.8 Nominal Bit Timing and Prescaler

This register is write-restricted and only writable if bit fields CCCR.CCE = 1 and CCCR.INIT = 1.

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 GCLK_CAN periods. tq = (NBRP + 1) mtq.

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.

Note: With a CAN clock (GCLK_CAN) of 8MHz, the reset value 0x06000A03 configures the CAN for a bit rate of 500 kBits/s.
Name: NBTP
Offset: 0x1C
Reset: 0x00000A33
Property: Write-restricted

Bit 3130292827262524 
 NSJW[6:0]NBRP[8] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000110 
Bit 2322212019181716 
 NBRP[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 
Bit 15141312111098 
 NTSEG1[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00001010 
Bit 76543210 
  NTSEG2[6:0] 
Access R/WR/WR/WR/WR/WR/WR/W 
Reset 0000011 

Bits 31:25 – NSJW[6:0] Nominal (Re)Syncronization Jump Width

ValueDescription
0x00 - 0x7F Valid values are 0 to 127. The actual interpretation by the hardware of this value is such that one more than the programmed value is used.

Bits 24:16 – NBRP[8:0] Nominal Baud Rate Prescaler

ValueDescription
0x000 - 0x1FF The value by which the oscillator frequency is divided for generating the bit time quanta. The bit time is built up from a multiple of this quanta. Valid values for the Baud Rate Prescaler are 0 to 511. The actual interpretation by the hardware of this value is such that one more than the value programmed here is used.

Bits 15:8 – NTSEG1[7:0] Nominal Time segment before sample point

ValueDescription
0x00 - 0x7F Valid values are 1 to 255. The actual interpretation by the hardware of this value is such that one more than the programmed value is used. NTSEG1 is the sum of Prop_Seg and Phase_Seg1.

Bits 6:0 – NTSEG2[6:0] Time segment after sample point

ValueDescription
0x00 - 0x7F Valid values are 0 to 127. The actual interpretation by the hardware of this value is such that one more than the programmed value is used. NTSEG2 is Phase_Seg2.