Baud Rate Control Function - NEC V850ES/F 3-L Series User Manual

CAN Controller (CAN)

18.3.7 Baud rate control function

(1)
(2)
Figure 18-18
Table 18-15
Segment name
Time segment 1 (TSEG1)
Time segment 2 (TSEG2)
Resynchronization Jump
Width (SJW)
Note
Prescaler
The CAN controller has a prescaler that divides the clock (f
CAN. This prescaler generates a CAN protocol layer basic system clock (f
derived from the CAN module system clock (f
("CnBRP - CANn module bit rate prescaler register" on page 580).
Data bit time (8 to 25 time quanta)
One data bit time is defined as shown in Figure 18-18 on page 549.
The CAN Controller sets time segment 1, time segment 2, and
reSynchronization Jump Width (SJW) of data bit time, as shown in
Time segment 1 is equivalent to the total of the propagation (prop) segment
and phase segment 1 that are defined by the CAN protocol specification. Time
segment 2 is equivalent to phase segment 2.
Sync segment
Segment setting
Segment setting
Settable range
2TQ to 16TQ
1TQ to 8TQ
1TQ to 4TQ
1. IPT: Information Processing Time
2. TQ: Time Quanta
Reference: The CAN protocol specification defines the segments constituting
the data bit time as shown in
User's Manual U18743EE1V2UM00
CANMOD
Data bit time(DBT)
Prop segment
Phase segment 1
Time segment 1(TSEG1)
Notes on setting to conform to CAN
specification
-
IPT of the CAN controller is 0TQ. To conform to the
CAN protocol specification, therefore, a length less
or equal to phase segment 1 must be set here.
This means that the length of time segment 1
minus 1TQ is the settable upper limit of time
segment 2.
The length of time segment 1 minus 1TQ or 4 TQ,
whichever is smaller.
.
Figure 18-19
Chapter 18
) supplied to
CAN
), and divided by 1 to 256
Figure 18-18
Phase segment 2
Time segment 2
(TSEG2)
Sample point (SPT)
)
TQ
.
549