Unread Message Status Register (Umsr) - Hitachi H8S/2628 Hardware Manual

15.3.16 Unread Message Status Register (UMSR)

UMSR is a 16-bit register containing status flags that indicate, for individual mailboxes (buffers),
that a received message has been overwritten by a new receive message before being read. When
overwritten by a new message, data in the unread receive message is lost.
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.
Initial Value R/W
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
0 R/(W)*
Description
[Setting condition]
•
When a new message is received before RXPR
is cleared
[Clearing condition]
•
Writing 1
•
When the received message has been
overwritten by a new message before being
read.
Rev. 1.0, 09/02, page 377 of 568