CHAPTER 11 FCAN CONTROLLER
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User’s Manual U14492EJ3V0UD
If ID based on location in memory is the same for multiple messages, the message buffer having the lowest
message number is selected.
When a message is stored, multiple message buffers are allocated to the same ID. At this time, data is stored in
the message buffers, starting from the message buffer with the lowest message number, as long as data is not
already stored in all the allocated message buffers (as long as the DN bit of the M_STATn register is not set to 1).
11.6 Mask Function
A mask linkage function can be defined for each received message.
This means that there is no need to distinguish between local masks and global masks.
When the mask function is used, the received message’s identifier is compared with the message buffer’s identifier
and the message can be stored in the defined message buffer regardless of whether the mask sets “0” or “1” as a
result of the comparison.
When the mask function is operating, a bit whose value is defined as “1” by masking is not subject to the
abovementioned comparison between the received message’s identifier and the message buffer’s identifier.
However, this comparison is performed for any bit whose value is defined as “0” by masking.
For example, let us assume that all messages that have a standard-format ID in which bits ID27 to ID25 = 0 and
bits ID24 and ID22 = 1 are to be stored in message buffer 14 (which is linked by mask 1 as explained in
11.10 (7)
).
The procedure for this example is shown below.
<1> Identifier bits to be stored in message buffer
ID28
ID27
ID26
ID25
ID24
ID23
ID22
ID21
ID20
ID19
ID18
x
0
0
0
1
x
1
x
x
x
x
Remark
x = don’t care
Messages with an ID in which bits ID27 to ID25 = 0 and bits ID24 and ID22 = 1 are registered (initialized) in
message buffer 14 (see
11.10 (6)
).
<2> Identifier bits set to message buffer 14 (example)
(Using CAN message ID registers L14 and H14 (M_IDL14 and M_IDH14))
ID28
ID27
ID26
ID25
ID24
ID23
ID22
ID21
ID20
ID19
ID18
0
0
0
0
1
0
1
0
0
0
0
ID17
ID16
ID15
ID14
ID13
ID12
ID11
ID10
ID9
ID8
ID7
0
0
0
0
0
0
0
0
0
0
0
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0
0
0
0
0
0
0
Message buffer 14 is set as a standard-format identifier linked to mask 1 (see
11.10 (7)
).
Содержание V850E/IA1 mPD703116
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