RL78/F13, F14 CHAPTER 18 CAN INTERFACE (RS-CAN LITE)
R01UH0368EJ0210 Rev.2.10 1396
Dec 10, 2015
18.7.3 Self-Test Mode (Loopback Mode)
In self-test mode, transmitted messages are compared with the receive rule of the own channel and the messages are
stored in a buffer if they have passed through the filter processing. Messages transmitted from other CAN nodes are
compared only with the receive rule for which the GAFLLB bit in the GAFLIDHj register (j = 0 to 15) is set to 0 (when a
message transmitted from another CAN node is received).
If the mirror function and self-test mode are both enabled, the self-test mode setting takes precedence.
(1) Self-Test Mode 0 (External Loopback Mode)
Self-test mode 0 is used to perform a loopback test within a channel including the CAN transceiver.
In self-test mode 0, transmitted messages are handled as messages received through the CAN transceiver and are
stored in a buffer. An ACK bit is generated to receive messages transmitted from the own CAN node.
Figure 18-11 shows the connection when self-test mode 0 is selected.
Figure 18-11. Connection when Self-Test Mode 0 is Selected
(2) Self-Test Mode 1 (Internal Loopback Mode)
In self-test mode 1, transmitted messages are handled as received messages and are stored in a buffer. An ACK bit is
generated to receive messages transmitted from the own CAN node.
In self-test mode 1, internal feedback from the internal CTXDi pin to the internal CRXDi pin is performed. The external
CRXDi pin input is isolated. The external CTXDi pin outputs only recessive bits.
Figure 18-12 shows the connection when self-test mode 1 is selected.
Figure 18-12. Connection when Self-Test Mode 1 is Selected
18.7.4 RAM Test
The RAM test function allows accesses to all CAN RAM addresses.
When the RAM test function is used, the RAM is divided into pages of 256 bytes each. RAM test page is set by the
RTMPS[2:0] bits in the GTSTCFG register. Data in the set page can be read from and written to the RPGACCr register (r
= 0 to 127). The available total RAM size is 544 bytes (H'0220).
CTXDi CRXDi
CAN transceiver
ACK
CTXDi
(internal)
CRXDi
(internal)
Remark i = 0
CTXDi
CRXDi
ACK
CTXDi
(internal)
Recessive level
CRXDi
(internal)
Remark i = 0
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