Data Sheet

3.4. LED feedback
The Tic Stepper Motor Controller has three LEDs to indicate its status.
The green LED indicates the USB status of the device. When you connect the Tic to a computer via a
USB cable, the green LED will start blinking slowly. The blinking continues until the Tic gets a particular
message from the computer that indicates that the Tic is recognized. After the Tic gets that message,
the green LED will be on, but it will flicker briefly when there is USB activity. During suspend mode (i.e.
when the Tic is only powered from USB and the computer has gone to sleep), the green LED will be
off.
The red LED indicates that an error is happening. The red LED is tied to the ERR pin. For more
information about error handling, see Section 5.4.
The yellow LED indicates the status of the stepper motor and also gives some information about what
errors are happening, if there are errors:
• If the stepper motor coils are energized (i.e. electrical current is flowing), then the yellow LED
will be on solid most of the time.
◦ If the motor is moving forward (i.e. the current velocity is positive), the yellow LED
will fade in for 0.5 s and then stay on at full brightness for 0.5 s:
◦ If the motor is moving in reverse, the yellow LED will fade out for 0.5 and then turn
on at full brightness for 0.5 s:
◦ If the motor is energized, but not moving, and there are no errors, the yellow LED
will turn on at full brightness:
◦ If the motor is energized and there is any error happening other than a safe start
violation, the yellow LED will stay on most of the time, but will periodically blink off
twice:
Tic Stepper Motor Controller User’s Guide © 2001–2018 Pololu Corporation
3. Getting started Page 16 of 150