AMIS-30621 Datasheet, PDF (41/59 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS−30621
LIN Lost Behavior
Introduction
When the LIN communication is broken for a duration of
25000 consecutive frames (= 1.30 s @ 19200 kbit/s)
AMIS−30621 sets an internal flag called “LIN lost”.
Dependant on the contents of RAM register SecPos[10:0] a
motion to the secure position will start followed by entering
the sleep mode.
Motion to Secure Position
AMIS−30621 is able to perform an autonomous motion to
the predefined secure position SecPos[10:0]. This
positioning starts after the detection of lost LIN
communication and in case RAM register SecPos[10:0] 0
0x400. The functional behavior depends if LIN
communication is lost during normal operation (see
Figure 25 case A) or at (or before) start−up (See Figure 25
state SHUTDOWN):
Power Up
OTP content is
copied in RAM
GetFullStatus
(LIN communication ON)
“SecPos[10:0]” from RAM register will be used. This can
be different from OTP register if earlier LIN master
communication has updated this. See also Secure Position
and command SetMotorParam.
1. If the LIN communication is lost there are two
possibilities:
I. If SecPos[10:0] = 0x400:
No secure positioning will be performed
AMIS−30621 will enter the SLEEP state
II. If SecPos[10:0] 0 0x400:
Perform a secure positioning. This is an
absolute positioning (slave knows its ActPos.
SecPos[10:0] will be copied in TagPos).
After the positioning is finished AMIS−30621
will enter the SLEEP state.
Important Remarks:
1. The secure position has a resolution of 11 bit.
2. Same behavior in case of HW2 float (= lost LIN
address). See also Hardwired Address HW2
A
SetMotorParam
(RAM content is overwritten)
LIN bus OK
No
No
LIN bus OK
Yes
SHUTDOWN
A
Figure 25. Flow Chart Powerup of AMIS−30621. Case
A: LIN Lost During Operation and LIN Lost at
Start−up Resulting in Shutdown
LIN Lost During Normal Operation
If the LIN communication is lost during normal operation,
it is assumed that AMIS−30621 is referenced. In other words
the ActPos register contains the “real” actual position. At
LIN – lost an absolute positioning to the stored secure
position SecPos is done. This is further called secure
positioning. Following sequence will be followed. See
Figure 26.
SecPos 0 0x400
No
Yes
Yes
Secure Positioning
to TagPos
Normal Function
SLEEP
SLEEP
Figure 26. Case A: LIN Lost During Normal Operation
LIN Lost Before or at Power On
If the LIN communication is lost before or at power on, no
correct GetFullStatus command is received. For that reason
the ShutDown state is not left and the stepper motor is kept
un−powered.
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