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DocID022729 Rev 3

This pin is an open drain output which can be used as the busy flag or synchronization 
signal according to the SYNC_EN bit value (STEP_MODE register).

The pin works as busy signal when the SYNC_EN bit is set low (default condition). In this 
mode the output is forced low while a constant speed, absolute positioning or motion 
command is under execution. The BUSY pin is released when the command has been 
executed (target speed or target position reached). The STATUS register includes a BUSY 
flag that is the BUSY pin mirror (see 

).

In the case of daisy chain configuration, BUSY pins of different ICs can be hard-wired to 
save host controller GPIOs.

The pin works as a synchronization signal when the SYNC_EN bit is set high. In this mode 
a step-clock signal is provided on the output according to a SYNC_SEL and STEP_SEL 
parameter combination (see 

).

By default an internal open drain transistor pulls the FLAG pin to ground when at least one 
of the following conditions occur:


Power-up or standby/reset exit



Overcurrent detection



Thermal warning



Thermal shutdown



UVLO



Switch turn-on event



Wrong command



Non-performable command.

It is possible to mask one or more alarm conditions by programming the ALARM_EN 
register (see 

). If the corresponding bit of the ALARM_EN register is 

low, the alarm condition is masked and it does not cause a FLAG pin transition; all other 
actions imposed by alarm conditions are performed anyway. In the case of daisy chain 
configuration, the FLAG pins of different ICs can be OR-wired to save host controller 
GPIOs.