Operation
Atlas® Digital Amplifier Complete Technical Reference
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4
At the end of this sequence Atlas will resume normal operations. This includes operation of the watchdog timer itself.
Unless a zero value has been loaded into the watchdog timeout value (thereby disabling the watchdog timeout), Atlas
will immediately begin counting SPI command intervals to determine if a another timeout has occurred.
4.8.6
Drive Enable
Atlas supports an
Enable
input signal that must be active for proper amplifier operation. This signal is useful for
allowing external hardware to automatically shut Atlas down. The signal has an active low interpretation.
The status of the
Enable
signal can be read using the command
GetSignalStatus
.
If the Enable signal becomes inactive (goes high) the following events occur:
• The current loop and power stage modules are disabled, thereby halting further motor output.
• The Drive Fault Status register records a Disabled fault condition.
• The Event Status register records a drive exception condition.
To recover from this condition the user should determine the nature of the fault using the
GetDriveFaultStatus
command. It may be desirable to power down Atlas to correct the condition.
If the condition is resolved but Atlas is not power cycled, the following sequence should be used to restore the drive
to normal operation:
• Clear the fault condition using the
ClearDriveFaultStatus
command.
• Clear the drive exception bit of the Event Status word using the
ResetEventStatus
command. It is not
possible to re-enable the current loop or the power stage module if the drive exception bit is still active.
• Re-enable the current loop and power stage modules using the
RestoreOperatingMode
command.
At the end of this sequence Atlas will resume normal operations. If the
Enable
signal is still inactive while the disable
bit of the Event Status register is being cleared, this bit will immediately be set again, and the recovery sequence must
be executed again.
4.8.7
Drive Fault Status Register
To simplify recovery from drive-related faults Atlas provides a Drive Fault Status register. This register is read using
the command
GetDriveFaultStatus
.
The bits in this register use a latch mechanism, meaning they are set by Atlas, and cleared by the user.
The following table indicates the contents of this register:
Watchdog timeout faults indicate that a serious safety condition has occurred. It is the responsibility of the user
to operate Atlas within safe limits.
Bit
Name
Description
0
Overcurrent
Set 1 to indicate an overcurrent event due to a short circuit,
overload in the drive output, or other such condition.
1-2
Reserved
May contain 0 or 1
3
Operating mode mismatch
Set 1 to indicate that Atlas received a torque command when
output was not enabled.
4
Watchdog timeout
Set 1 to indicate that the command watchdog has timed out.
