Data Sheet

moving, or if it is even connected. The LED blinking patterns above are based on the signals that the
Tic is sending to the on-board stepper motor driver.
To ensure that the Tic shows a complete blinking pattern instead of switching quickly between two or
more patterns, the yellow LED blinking pattern is only updated after it has completed. So if you make
a change to your system, you might have to wait for one or two seconds to see the LEDs respond.
The information expressed by the Tic’s LEDs can also be seen by connecting the Tic to a computer
via USB, running the Tic Control Center, and looking in the Status tab.
Startup blinking
When the Tic starts running, it tries to detect if it was reset by some special condition. If the
Tic experiences a brown-out reset, watchdog timer reset, software reset, stack overflow, or stack
underflow, the Tic will blink its yellow LED eight times over a one second period while the red LED is
on at startup. While it is doing this blinking, the Tic will not accept any commands, read any inputs, or
energize the stepper motor. You can see the cause of the last reset in the Tic Control Center software’s
“Last reset” field. This startup blinking was added in firmware version 1.02.
Bootloader mode
In bootloader mode, which is used for updating the firmware of the Tic and should only rarely be
needed, the LEDs behave differently. The green LED still indicates the USB status, but it is different:
after the bootloader gets a particular message from the computer that indicates that the bootloader
is recognized, the green LED will start doing a double blinking pattern every 1.4 seconds. The yellow
LED will usually be on solid, but it will blink quickly whenever a USB command is received. The red
LED will be on if and only if there is no firmware currently loaded on the device.
Tic Stepper Motor Controller User’s Guide © 2001–2018 Pololu Corporation
3. Getting started Page 18 of 150