Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 20 CAN CONTROLLER
R01UH0042EJ0500 Rev.5.00 Page 979 of 1513
Aug 12, 2011
20.8 CAN Controller Initialization
20.8.1 Initialization of CAN module
Before CAN module operation is enabled, the CAN module system clock needs to be determined by setting the
C0GMCS.CCP0 to C0GMCS.CCP3 bits by software. Do not change the setting of the CAN module system clock after
CAN module operation is enabled.
The CAN module is enabled by setting the C0GMCTRL.GOM bit.
For the procedure of initializing the CAN module, see 20.16 Operation of CAN Controller.
20.8.2 Initialization of message buffer
After the CAN module is enabled, the message buffers contain undefined values. A minimum initialization for all the
message buffers, even for those not used in the application, is necessary before switching the CAN module from the
initialization mode to one of the operation modes.
• Clear the C0MCTRLm.RDY, C0MCTRLm.TRQ, and C0MCTRLm.DN bits to 0.
• Clear the C0MCONFm.MA0 bit to 0.
Remark m = 00 to 31
20.8.3 Redefinition of message buffer
Redefining a message buffer means changing the ID and control information of the message buffer while a message is
being received or transmitted, without affecting other transmission/reception operations.
(1) To redefine message buffer in initialization mode
Place the CAN module in the initialization mode once and then change the ID and control information of the
message buffer in the initialization mode. After changing the ID and control information, set the CAN module to an
operation mode.
(2) To redefine message buffer during reception
Perform redefinition as shown in Figure 20-39.
(3) To redefine message buffer during transmission
To rewrite the contents of a transmit message buffer to which a transmission request has been set, perform
transmission abort processing (see 20.10.4 (1) Transmission abort process other than in normal operation
mode with automatic block transmission (ABT), 20.10.4 (2) Transmission abort process except for ABT
transmission in normal operation mode with automatic block transmission (ABT)). Confirm that
transmission has been aborted or completed, and then redefine the message buffer. After redefining the transmit
message buffer, set a transmission request using the procedure described below. When setting a transmission
request to a message buffer that has been redefined without aborting the transmission in progress, however, the 1-
bit wait time is not necessary.