CHAPTER 19 FCAN CONTROLLER (V850/SC3)
User’s Manual U15109EJ3V0UD
626
19.5.27 CANn synchronization control register (CnSYNC)
The CnSYNC register controls the data bit time for transmission speed.
This register can be read/written in 16-bit units.
The C2SYNC register is valid only in models
µ
PD703089Y and 70F3089Y.
Cautions 1. The CPU is able to read the CnSYNC register at any time.
2.
Writing to the CnSYNC register is enabled in initialization mode (when CnCTRL register’s
INIT bit = 1).
3.
The limit values of CAN protocol when setting the SPTRa bit and DBTRa bit are as follows (a
= 0 to 4).
••••
5
××××
BTL
≤≤≤≤
SPT (sample point)
≤≤≤≤
17
××××
BTL [4
≤≤≤≤
set values of SPTR4 to SPTR0
≤≤≤≤
16]
••••
8
××××
BTL
≤≤≤≤
DBT (data bit time)
≤≤≤≤
25
××××
BTL [7
≤≤≤≤
set values of DBTR4 to DBTR0
≤≤≤≤
24]
••••
SJW (synchronization jump width)
≤≤≤≤
DBT
−−−−
SPT
••••
2
≤≤≤≤
(DBT
−−−−
SPT)
≤≤≤≤
8
Remark
BTL = 1/f
BTL
(f
BTL
: CAN protocol layer basic system clock)
(1/2)
After reset: 0218H
R/W
Addresses: C1SYNC: xx3FFC5EH
C2SYNC: xx3FFC9EH
15
14
13
12
11
10
9
8
CnSYNC
0
0
0
SAMP
SJWR1
SJWR0
SPTR4
SPTR3
(n = 1, 2)
7
6
5
4
3
2
1
0
SPTR2
SPTR1
SPTR0
DBTR4
DBTR3
DBTR2
DBTR1
DBTR0
SAMP
Bit sampling specification
0
Sample data received at the sample point once
1
Sample received data three times and majority value used as sampled value
SJWR1
SJWR0
Synchronization jump width
Note
0
0
BTL
0
1
BTL
×
2
1
0
BTL
×
3
1
1
BTL
×
4
Note
As stipulated in the CAN protocol specification, Ver. 2.0 PartB active.
Remark
BTL
= 1/f
BTL
(f
BTL
: CAN protocol layer basic system clock)