upd70f3402 Renesas Electronics Corporation., upd70f3402 Datasheet - Page 648

• Manufacturer Part Number: upd70f3402
• Description: 32-/16-bit Single-chip Microcontroller With Can Interface
• Manufacturer: Renesas Electronics Corporation.

16.13 Diagnosis Functions and Special Operational Modes
The CAN module provides a receive-only mode, single-shot mode, and self-test mode to support CAN
bus diagnosis functions or the operation of special CAN communication methods.
16.13.1 Receive-only mode
The receive-only mode is used to monitor receive messages without causing any interference on the
CAN bus and can be used for CAN bus analysis nodes.
For example, this mode can be used for automatic baud-rate detection. The baud rate in the CAN mod-
ule is changed until “valid reception” is detected, so that the baud rates in the module match (“valid
reception” means a message frame has been received in the CAN protocol layer without occurrence of
an error and with an appropriate ACK between nodes connected to the CAN bus). A valid reception
does not require message frames to be stored in a receive message buffer (data frames) or transmit
message buffer (remote frames). The event of valid reception is indicated by setting the VALID bit of the
CnCTRL register (1).
648
Figure 16-54: CAN Module Terminal Connection in Receive-Only Mode
Fixed to
the recessive
level
Chapter 16 FCAN Controller
CTXDn
User’s Manual U16702EE3V2UD00
CAN macro
Tx
CRXDn
Rx