CAN Module
deveopmen
Rev.B2 for proof reading
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
228
For slots 14 and 15
The RemActive bit functions differently depending on how the CAN Control Register
’
s BasicCAN
(BasicCAN mode) bit is set.
When BasicCAN = 0 (operating normally), if the slot is set for remote frame transmission (or recep-
tion), the RemActive bit is set to 1.
When BasicCAN = 1 (operating in BasicCAN mode), the RemActive bit indicates which frame type
of message was received. During BasicCAN mode, slots 14 and 15 store the received data whether
it be a data frame or a remote frame.
If RemActive = 0, it means that the message stored in the slot is a data frame.
If RemActive = 1, it means that the message stored in the slot is a remote frame.
Bit 4: Automatic answering disable bit (RspLock)
This bit is useful for the slots set for remote frame reception, indicating the processing to be per-
formed after receiving a remote frame.
If this bit is set to 0, the slot automatically changes to a transmit slot after receiving a remote frame
and the message stored in the slot is transmitted as a data frame.
If this bit is set to 1, the slot stops operating after receiving a remote frame.
Note 1: This bit must always be set to 0 for any slots other than those set for remote frame reception.
Bit 5: Remote frame set bit (Remote)
Set this bit to 1 for the message slots that handle a remote frame.
Message slots can be set to handle a remote frame in the following two ways.
Set to transmit a remote frame and receive a data frame
The message stored in the message slot is transmitted as a remote frame. The slot automatically
changes to a data frame receive slot after it finished transmitting.
However, if it receives a data frame before it finishes transmitting a remote frame, the data frame is
stored in the message slot and the remote frame is not transmitted.
Set to receive a remote frame and transmit a data frame
The slot receives a remote frame. The processing to be performed after receiving a remote frame
depends on how the RspLock (automatic answering disable) bit is set.
Bit 6: Receive request bit (RecReq)
Set this bit to 1 when using any message slot as a receive slot.
Set this bit to 0 when using any message slot as a data frame transmit or remote frame transmit slot.
If the TrmReq (transmit request) bit and RecReq (receive request) bit both are set to 1, the operation
of the CAN module is indeterminate.
Bit 7: Transmit request bit (TrmReq)
Set this bit to 1 when using any message slot as a transmit slot.
Set this bit to 0 when using any message slot as a data frame receive or remote frame receive slot.