Freescale Semiconductor PXR4030, Reference Manual

Page: 295 / 1434

Boot Assist Module (BAM)
Freescale Semiconductor 9-15
PXR40 Microcontroller Reference Manual, Rev. 1
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)
.
Maximum and minimum speeds of the serial communication modules are defined by the MCU system
frequency and shown in the
Table 9-10 .
Table 9-9. Lookup Table for CAN Bit Timing.
Time quanta per bit
Time segment 1 Time Segment 2
RJW
PROPSEG PSEG1 PSEG2
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
Table 9-10. Maximum and Minimum Detectable Baud Rates
1
1
When the MCU operates with the PLL in normal mode with crystal oscillator as a reference clock source.
F
xtal
l
(MHz)
F
sys
=
1.5*F
xtal
(MHz)
Max Baud rate for CAN
(F
sys
/9)
2
(bps)
2
Limited by 1Mbps by CAN standard
Min CAN Baud rate
(F
sys
/25/256) bps
Max Baud rate for SCI
(F
sys
/160)(bps)
Min Baud rate for SCI
(F
sys
/16/2
16
)(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