AMIS-30621 Datasheet, PDF (40/43 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS-30621 LIN Microstepping Motordriver
Data Sheet
9.2.4.6.2 Reading frames
A reading frame uses an in-frame response mechanism.
That is: the master initiates the frame (synchronization field +
identifier field), and one slave sends back the data field
together with the check field. Hence, two types of identifiers
can be used for a reading frame:
- Direct ID, which points at a particular slave node, indicating
at the same time which kind of information is awaited from
this slave node, thus triggering a specific command. This ID
provides the fastest access to a read command but is
forbidden for any other action.
- Indirect ID, which only specifies a reading command, the
physical address of the slave node that must answer having
been passed in a previous writing frame, called a preparing
frame. Indirect ID gives more flexibility than a direct one,
but provides a slower access to a read command.
Notes
(1) A reading frame with indirect ID must always be
consecutive to a preparing frame. It will otherwise not be
taken into account.
(2) A reading frame will always return the physical address of
the answering slave node in order to ensure robustness in
the communication.
The reading frames used with the AMIS-30621 are the
followings:
• Type #5: 2, 4 or 8 Data bytes reading frame with a direct
IDs dynamically assigned to a particular slave node
together with an application command. A preparing frame
is not needed.
• Type #6: 8 Data bytes reading frame with 0x3D identifier.
This is intrinsically an indirect type, needing therefore a
preparation frame. It has the advantage to use a reserved
identifier.
9.2.4.6.3 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: 2 Data bytes writing frame with dynamically assigned identifier.
bit 7
*
1
1
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
Identifier
Data1
Data2
*) according to parity computation
• Type #8: 8 Data bytes writing frame with 0x3C identifier.
bit 7
0
1
1
AppCMD :
bit 6
0
bit 5
1
bit 4
bit 3
1
1
AppCMD = 0x80
CMD[6:0]
AD[6:0]
0xFF
0x80 indicates that Data2 contains an
application command byte
bit 2
1
bit 1
0
bit 0
0
Identifier
Data1
Data2
Data3
Data4-8
CMD[6:0] : Command byte
AD[6:0] : Slave node’s physical address
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