Oki MSM9225B, User Manual

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MSM9225B User’s Manual
Chapter 2 Register Descriptions
2 – 7
2.3.2 Identifier 0 (IDR0: x1hex)
This register sets the frame format, data length code, and a part of the identifier.
The bit configuration is as follows:
MSB IDFM DLC3 DLC2 DLC1 DLC0 IDB28 IDB27 IDB26 LSB IDR0 (x1hex), R/W: R/W
Initial
value:
Undefined Undefined Undefined Undefined Undefined Undefined Undefined Undefined
0 ID26
1
0 ID27
1
0 ID28
1
DLC3 DLC2 DLC1 DLC0 Number of bytes of a data field
0 0 0 0 0
0 0 0 1 1
• • • • •
• • • • •
0 1 1 1 7
1 0 0 0 8
0 Standard format (ID = 11 bits)
1 Extended format (ID = 29 bits)
Figure 2-3 Identifier 0 (IDR0)
(1) Identifier: IDB28 to IDB26
These bits set the identifier field.
For standard format (IDFM = 0), the higher 3 bits (ID28 to ID26) of the 11 bits (ID28 to ID18) are set.
For extended format (IDFM = 1), the higher 3 bits (ID28 to ID26) of the 29 bits (ID28 to ID0) are set.
At reset, these bits are undefined.
Note on Identifier
The identifier field (ID28 to ID18 for standard format, and ID28 to ID0 for extended format) is
overwritten with the received message’s identifier, when the message box for which the group message
function has been specified receives the message.
(2) Data length code: DLC3 to DLC0
These bits set the number of bytes of a data field. 0 to 8 can be set. Do not set values other than 0 to 8.
At reset, these bits are undefined.
Notes on Data Length Code
When the received data length code (hereafter DLC) matches the DLC set in the message box, the
number of bytes of data indicated by the received DLC is received and written to the message box.
When the received DLC does not match the DLC set in the message box, the MSM9225B operates as
follows:
- The received DLC is written into the DLC field in the message box.
- The number of bytes of data indicated by the received DLC is received and written to the message box.
(3) Frame format setting: IDFM
This bit sets the frame format.
At reset, the IDFM bit is undefined.
Table 2-3 Frame Format
IDFM Operation
0 Standard format (ID = 11 bits)
1 Extended format (ID = 29 bits)
B
B