AMIS-30621 Datasheet, PDF (39/43 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS-30621 LIN Microstepping Motordriver
9.2.4.6.1 Writing Frames
A writing frame is sent by the LIN Master to send
commands and/or information to the Slave nodes.
According to the LIN specification, identifiers are to be used
to determine a specific action. If a physical addressing is
needed, then some bits of the Data field can be dedicated
to this, as illustrated in the example below.
Data Sheet
Another possibility is to determine the specific action within
the Data field in order to use less identifiers. One can for
example use the reserved identifier 0x3C and take
advantage of the 8-byte Data field to provide a physical
address, a command and the needed parameters for the
action, as illustrated in the example below.
Note
Bit 7 of byte Data1 must be at ‘1’ since the LIN specification
requires that contents from 0x00 to 0x7F must be reserved for
broadcast messages (0x00 being for the “Sleep” message).
The writing frames used with the AMIS-30621 are the
followings:
• Type #1: General purpose 2 or 4 Data bytes writing frame
with a dynamically assigned identifier
This type is dedicated to short writing actions when the bus
load can be an issue. They are used to provide direct
command to one (Broad = ‘1’) or all the slave nodes (Broad
= ‘0’). If Broad = ‘1’, the physical address of the slave node
is provided by the 7 remaining bits of DATA2. DATA1 will
contain the command code (see § 9.2.4.7), while, if
present, DATA3 to DATA4 will contain the command
parameters, as shown below.
• Type #2: 2, 4 or 8 Data bytes writing frame with an
identifier dynamically assigned to an application
command, regardless of the physical address of
the circuit.
• Type #3: 2 Data bytes writing frame with an identifier
dynamically assigned to a particular slave node
together with an application command. This
type of frame requires that there are as many
dynamically assigned identifiers as there are
AMIS-30621 circuits using this command
connected to the LIN bus.
• Type #4: 8 Data bytes writing frame with 0x3C identifier.
The structure is similar to Type #1 but uses the reserved ID
0x3C. Type #1 has the advantage to be shorter than Type #4.
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