AMIS-30621 Datasheet, PDF (14/43 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS-30621 LIN Microstepping Motordriver
Data Sheet
9.2.1.3 External Switch and HW2 Pin
Pin SWI and hardwired address pin HW2 (see § 9.2.4.5) will
alternatively attempt to source and sink a current in/from
the external switch (see application schematic) to test
whether it is ON or OFF. This current is set around 10mA
when a 1kW external series resistor is used.
This can be represented by the following time diagram (The
timings are given in § 6).
If the switch is detected ON (closed), then the flag <ESW>
is raised. The status of this flag can be read by the
application via a GetActualPos, a GetStatus or a
GetFullStatus reading frame. At the falling edge of
every current pulse (at around 1kHz), the stepper-motor
actual position is refreshed (register ActPos, see § 9.2.2.9),
so that the master node may get synchronous information
about the state of the switch together with the position of
the motor. The position is then given with an accuracy of ±
1 half-step (or micro-step, depending of the programmed
stepping mode). The block diagram below shows how this
function is implemented for HW2.
With the following truth table:
State
Float
Float
Float
Float
HW2Lo
HW2Lo
HW2Lo
HW2Lo
HW2Hi
HW2Hi
HW2Hi
HW2Hi
Drive LS
1
1
0
0
1
1
0
0
1
1
0
0
Drive HS
0
0
1
1
0
0
1
1
0
0
1
1
HW2_CMP
0
1
0
1
0
1
0
1
0
1
0
1
New State
Float
HW2Hi
Float
HW2Lo
HW2Lo
HW2Hi
Float
HW2Lo
Float
HW2Hi
HW2Hi
HW2Lo
HW2Hi
HW2Lo
HW2_CMP
Drive LS
Drive HS
address = "1"
address = "0"
CMP output; active high if low resistance
detected by the LS or HS Ohm-meter
request from digital to turn on the low-
side part of the Ohm-meter
request from digital to turn on the high-
side part of the Ohm-meter
note that e.g. if HW2 is connected to GND, LS-part will
report "float" while HS-part will report "low resistance
detected"
Note:
If HW2 is detected to be floating, motion to the secure position is performed.
AMI Semiconductor - Rev. 1.4
www.amis.com
14