Renesas M32R/ECU Series User Manual page 602

13
(2) RR (Receive Request) bit (Bit 1)
To use the message slot as a receive slot, set this bit to "1". To use the message slot as a data frame or
remote frame transmit slot, set this bit to "0".
If TR (Transmit Request) bit and RR (Receive Request) bit both are set to "1", device operation is undefined.
(3) RM (Remote) bit (Bit 2)
To handle remote frames in the message slot, set this bit to "1". There are following two methods of settings
to handle remote frames:
• Set for remote frame transmission
The data set in the message slot is transmitted as a remote frame. When the CAN module finished
sending, the slot automatically changes to a data frame receive slot. However, if a data frame is received
before the CAN module finished sending a remote frame, the received data is stored in the message slot
and the remote frame is not transmitted.
• Set for remote frame reception
Remote frames are received. The processing to be performed after receiving a remote frame is selected
by RL (automatic response inhibit) bit.
(4) RL (Automatic Response Inhibit) bit (Bit 3)
This bit is effective when the message slot has been set as a remote frame receive slot. It selects the
processing to be performed after receiving a remote frame. If this bit is set to "0", the message slot automati-
cally changes to a transmit slot after receiving a remote frame and transmits the data set in it as a data frame.
If this bit is set to "1", the message slot stops operating after receiving a remote frame.
Note: • Always set this bit to "0" unless the message slot is set for remote frame reception.
(5) RA (Remote Active) bit (Bit 4)
This bit functions differently for slots 0-13 and slots 14 and 15.
• Slots 0–13
This bit is set to "1" when the message slot is set for remote frame transmission (reception). Then, when
remote frame transmission (reception) is completed, the bit is cleared to "0".
• Slots 14 and 15
The function of this bit differs deepening on how the CAN Control Register BCM (BasicCAN Mode) bit is
set. If BCM = "0" (normal operation), this bit is set to "1" when the message slot is set for remote frame
transmission (reception). If BCM = "1" (BasicCAN), this bit indicates which type of frame is received.
During BasicCAN mode, the received data is stored in slots 14 and 15 for both data and remote frames.
If RA = "0", it means that the frame stored in the slot is a data frame. If RA = "1", it means that the frame
stored in the slot is a remote frame.
(6) ML (Message Lost) bit (Bit 5)
This bit is effective for receive slots. It is set to "1" when the message slot contains unread received data
which is overwritten by reception. This bit is cleared by writing "0" in software.
13.2 CAN Module Related Registers
13-55
CAN MODULE
32180 Group User's Manual (Rev.1.0)