![](http://datasheet.mmic.net.cn/370000/UPD70F3116A_datasheet_16743820/UPD70F3116A_557.png)
CHAPTER 11 FCAN CONTROLLER
557
User’s Manual U14492EJ5V0UD
(8) CAN message status registers 00 to 31 (M_STAT00 to M_STAT31)
The M_STATn register indicates the transmit/receive status information of each message buffer (n = 00 to
31).
These registers are read-only, in 8-bit units.
Cautions 1. Writing directly to M_STATn register cannot be performed. Writing must be performed
using CAN status set/clear register n (SC_STATn).
2. Messages are transmitted only when the M_STATn register’s TRQ and RDY bits have
been set (to 1).
7
0
M_STATn
(n = 00 to 31)
6
0
5
0
4
0
3
RFU
Note 1
2
DN
1
TRQ
0
RDY
Note 2
Address
See
Table 11-24
Initial value
Undefined
Bit position
Bit name
Function
2
DN
This is the message update flag.
0: No message was received after DN bit was cleared.
1: At least one message was received after DN bit was cleared.
When the DN bit has been set (to 1) by the transmit message buffer, it indicates that the
message buffer has received a remote frame.
When this message is sent, the DN bit is automatically cleared (to 0).
When a frame is again received in the receive message buffer for which the DN bit has
been set (to 1), an overwrite condition occurs and the M_CTRLn register’s MOVR bit is
set (to 1) (n = 00 to 31).
1
TRQ
This is the transmit request flag.
0: Message transmission disabled
1: Message transmission enabled
A transmit request is processed as a CAN module only when the RDY bit is set to 1.
A remote frame is transmitted for the receive message buffer in which the TRQ bit is set to 1.
0
RDY
This is the transmit message ready flag.
0: Message is not ready.
1: Message is ready.
A receive operation is performed only for a message buffer in which the RDY bit is set to
1 during reception.
A transmit operation is performed only for a message buffer in which the RDY bit is set to
1 and the TRQ bit is set to 1 during transmission.
Notes 1.
RFU (Reserved for Future Use) indicates a reserved bit. 0 or 1 is read from this bit regardless of
the message buffer setting.
2.
The FCAN controller incorporated in the V850E/IA1 can perform reception even if the RDY bit is
not set. However, in products other than the V850E/IA1, the RDY bit must be set for reception. In
order to maintain software compatibility, be sure to set the RDY bit even for the FCAN controller of
the V850E/IA1 prior to reception.