upd70f3422gj-gae-qs-ax Renesas Electronics Corporation., upd70f3422gj-gae-qs-ax Datasheet - Page 711

• Manufacturer Part Number: upd70f3422gj-gae-qs-ax
• Description: 32-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

CAN Controller (CAN)
19.8.1 Initialization of CAN module
19.8.2 Initialization of message buffer
19.8.3 Redefinition of message buffer
19.8 CAN Controller Initialization
(1)
(2)
(3)
Before CAN module operation is enabled, the CAN module system clock
needs to be determined by setting the CnGMCS.CCP0 to CnGMCS.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 CnGMCTRL.GOM bit.
For the procedure of initializing the CAN module, “Operation of CAN
Controller“ on page 745.
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 CnMCTRLm.RDY, CnMCTRLm.TRQ, and CnMCTRLm.DN bits to
• Clear the CnMCONFm.MA0 bit to 0.
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.
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.
To redefine message buffer during reception
Perform redefinition as shown in Figure 19-37.
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
“Transmission abort in normal operation mode“ on page 727 and
“Transmission abort in normal operation mode with automatic block
transmission (ABT)“ on page 727). 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.
Preliminary User’s Manual U17566EE1V2UM00
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Chapter 19
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