ICP DAS USA I-7530 User Manual page 60

ГК Атлант Инжиниринг – официальный представитель в РФ и СНГ
The formulas are shown below.
Because the T
syns
presented as below.
T = 1 TQ + (PRS+1) * TQ + (PHS1+1)* TQ +(PHS2 +1)* TQ
bit
And the sample point is defined below:
Sample point = (T
Because the maximum value limitation of the register PRS, PHS1, and
PHS2, the numbers of the Time Quantum always keeps in the range of 8
~ 25. Therefore, users can use register BRP to scale it. For example, if set
the BRP to 25 (the register value of the BRP is 24), the numbers of the
Time Quantum is 500 / 25 = 20. Users can change the value of the PRS,
PHS1, and PHS2 to adjust the required sample point.
For example:
If users want to set the CAN baud rate to "40K" by user-defined
method and use the sample point 60%, set the clock mode to be 1
because the CAN Baud rate is more than 12K bps. When the Clock mode
is 1, the MCU uses X2 mode and the system clock is 20MHz. Otherwise,
the MCU uses X1 mode, and the system clock is 10MHz. The following
steps will guide users to calculate the Bit Timing register step by step.
1. Calculate the numbers of the TQ:
Numbers of the TQ = (System clock) / (CAN Baud Rate)
I-7530, I-7530-FT, I-7530A, I-7565 User's Manual (Version 1.3, Apr/2015) -------- 60
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T = (PRS+1) * TQ
prs
T = (PHS1+1)* TQ
phs1
T = (PHS2 +1)* TQ
phs2
is defined to 1 TQ, therefore one bit time can be
+ T + T
syns prs
= (3 + PRS + PHS) / (4+PRS+PHS1+PHS2)
= 20 M /40 k
=500
) / (T + T + T
phs1 syns prs
+ T )
phs1 phs2