User guide

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72
STALL
The STALL input sets the minimum speed below which the motor will
stall. This value is significant in ensuring that the motor reaches its
required position. If the STALL speed is set too high, the motor will
overshoot and then hunt back to the correct position. If set too low,
the motor will stall out before the required position is reached.
The voltage at this input will normally be set by a divider chain.
It is not intended as a user control.
TRAP
The TRAP (Trapezium Point) input is used to set the distance from
the search position at which the motor will start to decelerate. This
value is significant in ensuring that the motor reaches its required
position. If the TRAP is set too high, the motor will decelerate too
slowly, overshoot and then hunt back to the correct position. If set
too low, the motor and gearbox will be unnecessarily stained by harsh
deceleration.
The voltage at this input will normally be set by a divider chain.
It is not intended as a user control.
FERR
The FERR (Following Error) input is used to set the allowed error
between the requested position and the motor position. Clearly the
lowest value is preferred as it equates to the highest accuracy.
However issues such as noise pick-up and variable load make it
impractical to attain a zero following error. If FERR is set to a value
lower than a particular application can attain, the servo loop will
become unstable and hunting will occur. The FERR input is linearly
calibrated to 16 bit resolution. That is:
FERR=0V equates to 0 bit allowed inaccuracy.
FERR=5V equates to 16 bits allowed inaccuracy.
SERVO
This control input should be connected to GND for servo operation.
T
HIGH STALL SPEED
V
LOW STALL SPEED
T
V
T
HIGH TRAP POINT
V
LOW TRAP POINT
T
V