Baud Rate Register Configuration - ICP DAS USA I-2533 User Manual

3.4 Baud Rate Register Configuration

The I-2533 supports the baud register configuration. Users can directly
configure the baud by write the proper value of the baud register. This is
useful if users want to adjust the position of the sampling point of a CAN
message. The baud rate register is active when the value baud is set to zero
and the rotary switch is set to 'A'. The following steps is helpful for configure
the baud register.
Step 1: Calculate the proper value of the baud register. The baud register is
divided into 4 parts as below.
(1) Calculate the time quantum which is the value of 36000000 divided
by the value of the CAN buad which you would like to use. For
example, if you want to use 250kbps, then 36000000/250000=72.
Because the time quantum must be integer, if the time quantum
can't be integer, it indicates that the baud rate can't be supported
by the I-2533.
(2) The time quantum must be the product of the (BRP+1) and
1+(TSEG1+1)+(TSEG2+1). Because the limitation of the value of
TSEG1 and TSEG2, the time quantum divided by (BRP+1) must be
in the range of 3 ~ 25. Therefore select a proper integer value of
the BRP to fit the condition. For example, if the time quantum are
72. The BRP may be 2, 3, 5, 7, 8, 11, 17, 23, and 35. If the BRP is
selected to 5, the 1+(TSEG1+1)+(TSEG2+1) is 72/(5+1)=12.
Select the TSEG1 and TSEG2 are 9 and 0 respectively. In this case,
the sampling point is (1+9+1)/(1+9+1+0+1)=91.6%. The register
value is 0x00090005.
I-2533 User Manual (ver. 1.1, 2013/05/31) ------22