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Operation Theory 75
4.5 Counters
There are four counters for each axis of this motion controller.
They are described in this section.
Command position counter: counts the number of output pulses
Feedback position counter: counts the number of input pulses
Position error counter: counts the error between command and
feedback pulse numbers.
General purpose counter: The source can be configured as com-
mand position, feedback position, manual pulser, or half of ASIC
clock.
Target position recorder: A software-maintained target position
value of latest motion command.
4.5.1 Command Position Counter
The command position counter is a 28-bit binary up/down counter.
Its input source is the output pulses from the motion controller. It
provides the information of the current command position. It is
useful for debugging the motion system.
Our motion system is an open loop type. The motor driver receives
pulses from motion controller and drive the motor to move. When
the driver is not moving, we can check this command counter and
see if there is an update value on it. If it is, it means that the pulses
have seen sent and the problem could be on the motor driver. Try
to check motor driver’s pulse receiving counter when this situation
is happened.
The unit of command counter is in pulse. The counter value could
be reset by a counter clear signal or home function completion.
Users can also use a software command counter setting function
to reset it.
4.5.2 Feedback Position Counter
The feedback position counter is a 28-bit binary up/down counter.
Its input source is the input pulses from the EA/EB pins. It counts
the motor position from motor’s encoder output. This counter