PXR40RM Datasheet, PDF (295/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

Boot Assist Module (BAM)
quantas per bit and achieve minimum difference between measured value and duration of the 40 CAN bits,
to be programmed with selected pair of the parameters.
The CAN controller can be programmed with 8 to 25 number of quantas per bit. The bit timing parameters,
can be selected by the baud rate detection routine, are shown in the Table 9-9. See the parameters
descriptions in the FlexCAN block guide)
.
Table 9-9. Lookup Table for CAN Bit Timing.
Time quanta per bit
Time segment 1
PROPSEG
PSEG1
Time Segment 2
PSEG2
RJW
8
1
3
3
2
9
2
3
3
2
10
3
3
3
2
11
4
3
3
2
12
3
4
4
2
13
4
4
4
3
14
5
4
4
3
15
6
4
4
4
16
7
4
4
3
17
8
4
4
3
18
7
5
5
4
19
8
5
5
4
20
7
6
6
4
21
8
6
6
4
22
7
6
6
4
23
8
6
6
4
24
7
7
7
4
25
8
7
7
4
Maximum and minimum speeds of the serial communication modules are defined by the MCU system
frequency and shown in the Table 9-10.
Table 9-10. Maximum and Minimum Detectable Baud Rates¹
F_xtall
(MHz)
F_sys =
1.5*F_xtal
(MHz)
Max Baud rate for CAN Min CAN Baud rate Max Baud rate for SCI Min Baud rate for SCI
(F_sys/9)²(bps)
(F_sys/25/256) bps
(F_sys/160)(bps)
(F_sys/16/2¹⁶)(bps)
8
12
1M
1875
75K
11.5
12
18
2812.5
112.5K
17.2
16
24
3750
150K
23
20
30
4687.5
187.5K
28.6
40
1 _{When the MCU operates with the PLL in normal mode with crystal oscillator as a reference clock source.}
2 _{Limited by 1Mbps by CAN standard}
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
9-15