Unread Message Status Register (Umsr) - Renesas H8SX/1520 Series Hardware Manual

Section 13 Controller Area Network (HCAN)

13.3.16 Unread Message Status Register (UMSR)

UMSR indicates that a received message which has not been read is overwritten by a new receive
message. In this case, the message which has not been read is lost.
Bit
Bit Name
Initial Value
R/W
Bit
Bit Name
Initial Value
R/W
Note: * Only 1 can be written to these bits, to clear the flags.
Bit Bit Name
15 UMSR7
14 UMSR6
13 UMSR5
12 UMSR4
11 UMSR3
10 UMSR2
9 UMSR1
8 UMSR0
7 UMSR15
6 UMSR14
5 UMSR13
4 UMSR12
3 UMSR11
2 UMSR10
1 UMSR9
0 UMSR8
Note: * Only 1 can be written to clear the flag.
Rev. 3.00 Mar. 14, 2006 Page 474 of 804
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15 14
UMSR7 UMSR6 UMSR5
0 0
R/(W)* R/(W)* R/(W)*
7 6
UMSR15 UMSR14 UMSR13
0 0
R/(W)* R/(W)* R/(W)*
Initial
Value
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
13 12 11
UMSR4 UMSR3
0 0 0
R/(W)* R/(W)*
5 4 3
UMSR12 UMSR11
0 0 0
R/(W)* R/(W)*
R/W Description
R/(W)* The received message has been overwritten by a
new message before being read.
R/(W)*
[Setting condition]
R/(W)*
•
When a new message is received before
R/(W)*
RXPR is cleared
R/(W)*
[Clearing conditions]
R/(W)*
•
Writing 1
R/(W)*
R/(W)*
R/(W)*
R/(W)*
R/(W)*
R/(W)*
R/(W)*
R/(W)*
R/(W)*
R/(W)*
10 9
UMSR2 UMSR1 UMSR0
0 0
R/(W)* R/(W)* R/(W)*
2 1
UMSR10 UMSR9 UMSR8
0 0
R/(W)* R/(W)* R/(W)*
8
0
0
0