Start Initialization
Configure Message Objects
Configure CAN Bit Timing
Finish Initialization
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Functional Description
23.3.8 CAN Operation
After hardware reset, the Init bit in the CAN control register (DCAN CTL) is set and all CAN protocol
functions are disabled. The CAN module must be initialized before operating it. Figure 23-3 illustrates the
basic initialization flow for the CAN module.
23.3.8.1 CAN Module Initialization
A general CAN module initialization would mean the following two critical steps:
• Configuration of the CAN bit timing
• Configuration of message objects
To initialize the CAN controller, the CPU has to set up the CAN bit timing and those message objects that
have to be used for CAN communication. Message objects that are not needed, can be deactivated.
Figure 23-3. CAN Module General Initialization Flow
23.3.8.1.1 Configuration of CAN Bit Timing
The CAN module must be in initialization mode to configure the CAN bit timing.
For CAN bit timing software configuration flow, see Figure 23-4.
Step 1: Enter initialization mode by setting the Init (Initialization) bit in the CAN control register.
While the Init bit is set, the message transfer from and to the CAN bus is stopped, and the status of the
CAN_TX output is recessive (high).
The CAN error counters are not updated. Setting the Init bit does not change any other configuration
register.
Also, note that the CAN module is in initialization mode on hardware reset and during Bus-Off.
3887
SPRUH73H–October 2011–Revised April 2013 Controller Area Network (CAN)
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