AMIS-30621 LIN Micro-stepping Motor Driver
Data Sheet
15.6.3. Preparing Frames
A preparing frame is a writing frame that warns a particular slave node that it will have to answer in the next frame (hence a reading
frame). A preparing frame is needed when a reading frame does not use a dynamically assigned direct ID. Preparing and reading
frames must be consecutive. A preparing frame will contain the physical address of the LIN slave node that must answer in the reading
frame, and will also contain a command indicating which kind of information is awaited from the slave.
The preparing frames used with the AMIS-30621 can be of Type #7 or Type #8 described below.
• Type #7: two data bytes writing frame with dynamically assigned identifier.
Preparing Frame
Byte
Content
Structure
Bit 7
Bit 6
*
Bit 5
0
Bit 4
ID4
Bit 3
ID3
CMD[6:0]
AD[6:0]
Bit 2
ID2
Bit 1
ID1
Bit 0
ID0
*
1
1
0
1
Identifier
Data 1
2
Data 2
Where:
(*)
According to parity computation
• Type #8: eight data bytes writing frame with 0x3C identifier.
SetDualPositioning Writing Frame
Structure
Byte
Content
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
1
1
1
1
0
0
0
1
2
3
4
5
6
7
Identifier
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
Data 8
AppCMD = 0x80
CMD[6:0]
1
1
AD[6:0]
Data4[7:0]
Data5[7:0]
Data6[7:0]
Data7[7:0]
Data8[7:0]
8
Where:
AppCMD:
CMD[6:0]:
AD[6:0]:
If = ‘0x80’ this indicates that data 2 contains an application command.
Application Command “byte”.
Slave node physical address.
Datan[7:0]: Data transmitted.
15.6.4. Dynamic Assignment of Identifiers
The identifier field in the LIN datagram denotes the content of the message. Six identifier bits and two parity bits are used to represent
the content. The identifiers 0x3C and 0x3F are reserved for command frames and extended frames. Slave nodes need to be very
flexible to adapt itself to a given LIN network in order to avoid conflicts with slave nodes from different manufacturers. Dynamic
assignment of the identifiers will fulfill this requirement by writing identifiers into the circuits RAM. ROM pointers are linking commands
and dynamic identifiers together. A writing frame with identifier 0x3C issued by the LIN master will write dynamic identifiers into the
RAM. One writing frame is able to assign 4 identifiers, therefore 3 frames are needed to assign all identifiers. Each ROM pointer
ROMp_x [3:0] place the corresponding dynamic identifier Dyn_ID_x [5:0] at the correct place in the RAM (see Table 1: LIN – Dynamic
Identifiers Writing Frame).
When setting <BROAD> to zero broadcasting is active and each slave on the LIN bus will store the same dynamic identifiers, otherwise
only the slave with the corresponding slave address is programmed.
AMI Semiconductor – Sept. 2007, Rev 1.5
39
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