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CHAPTER 23 CAN CONTROLLER
23.15 Setting the CAN Direct Mode Register
The MB90390 series provides a clock modulator for the system clock. Since the CAN
controller is not able to operate with a modulated clock, the unmodulated clock is
provided to the CAN controller independently from the clock modulator settings.
■ CAN Direct Mode Register (CDMR)
Figure 23.15-1 Configuration of the CAN Direct Mode Register (CDMR)
Address:
CAN0: 00356E
R/W
:
Readable and writable
X
:
Undefined value
-
:
Undefined
■ CAN Direct Mode Register Contents
Table 23.15-1 Function of the DIRECT Bit of the CAN Direct Mode Register
Bit name
bit7 to bit1
Undefined
bit0
DIRECT
518
bit
7
6
5
4
H
-
-
-
-
-
-
-
-
The value "1" should be written to this bit when the clock modulation is disabled.
Then, the CAN Controller skips synchronization to the modulated clock, making
the communication between CAN and CPU as fast as possible.
The value "0" must be written to this bit if the clock modulation is enabled in order
to synchronize modulated system clock and unmodulated CAN clock.
3
2
1
0
CDMR
-
-
-
DIRECT
Initial value
X X X X X X X 0
-
-
-
R/W
Function
−
B
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