Motion Monitoring & Control
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Juno Step Motor Control IC User Guide
12
attempt to recover by deasserting, and then asserting, the
Enable
signal. The
Enable
signal must be in the deasserted
state for at least 150
μ
Sec for the request to be recognized.
When an Enable-based recovery request is recognized Juno attempts to clear the Event Status register and the Drive
Fault Status register, and will continue to do so until the conditions which caused the
FaultOut
to go active are no longer
present. At this point
FaultOut
will be deasserted and Juno will return to normal operations.
Example
An application uses a thermistor mounted on the motor body and programs the fault out mask to generate a
FaultOut
signal when the motor gets too hot. Juno’s default event action is left unchanged which results in motor output being
disabled. External logic monitors the
FaultOut
signal and when it goes active, the external logic delays 200
μ
Sec,
deasserts the
Enable
signal for 200
μ
Sec, and then restores
Enable
to an asserted condition. Once the temperature has
dropped sufficiently motor operation will then proceed normally and the
FaultOut
signal will be deasserted.
12.4 Host Interrupts
Interrupts allow a host microprocessor or other external circuitry to be automatically notified if a special Juno
condition occurs. For this purpose Juno provides a
HostInterrupt
signal.
HostInterrupt
functions similarly to
FaultOut
but
provides a separate programmable mask.
Any or all of Event Status register bits may be programmed to cause an interrupt. If a 1 is stored in the mask, then a
1 in the corresponding bit of the Event Status register will cause an interrupt to occur. Juno continually and
simultaneously scans the Event Status register and interrupt mask to determine if an interrupt has occurred. When an
interrupt occurs, the
HostInterrupt
signal is made active.
To recover from an interrupt, Juno serial host commands may be used. Alternatively, Enable-based event recovery may
be used. Once a valid recovery sequence is sent by external circuitry, Juno will attempt to clear the Event status register
along with the
HostInterrupt
signal.
12.5 Trace
Figure 12-2:
Example
Motion Trace
Capture
Trace is a powerful Juno IC feature that allows various parameters and registers to be continuously captured and stored
to an internal RAM buffer. The captured data may later be downloaded by PMD Corp.’s Pro-Motion Windows-based
software. Traces are useful for optimizing performance, verifying trajectory behavior, capturing sensor data, or to assist
with any type of monitoring where a precise time-based record of the system’s behavior is required.
Trace activity with the Juno step motor ICs is undertaken using serial host commands. Most users will not concern
themselves with the protocol required to achieve this and will use a program such as Pro-Motion to set up and display
trace results. For users wishing to write their own trace software however, refer to the
Juno Velocity & Torque Control IC
User Guide
.
