Data Sheet

You might notice that the Tic only performs the desired movement for about a second before it
stops moving and the red LED turns on, indicating an error. This is because of the Tic’s command
timeout feature: by default, the Tic’s “Command timeout” error will happen if it does not receive certain
commands periodically (see Section 5.4 for details), causing the motor to stop. You can run ticcmd
--reset-command-timeout every second to get around this, or you can disable the command timeout
feature using the Tic Control Center: uncheck the “Enable command timeout” checkbox in the “Serial”
box.
To get the current status of the Tic, try running these commands, which give different levels of detail:
ticcmd --status
ticcmd --status --full
If the help screen printed by ticcmd when you run it with no arguments is not enough for you and you
want a more detailed explanation of the commands that ticcmd supports, see Section 8.
If you want to write your own software to control the Tic instead of just using ticcmd or the Tic Control
Center, see Section 12.
4.5. Setting up serial control
This section explains what kind of serial interface the Tic has and how to connect a microcontroller or
other TTL serial device to it so that you can send commands to control the Tic. The Tic Stepper Motor
Controller library for Arduino [https://github.com/pololu/tic-arduino] makes it particularly easy to control
the Tic from an Arduino or Arduino-compatible board such as an A-Star 32U4 [https://www.pololu.com/
a-star].
About the serial interface
The RX and TX pins of the Tic provide its serial interface. The Tic’s RX pin is an input, and its TX pin
is an output. Each pin has an integrated 100 kΩ resistor pulling it up to 5 V and a 470 Ω series resistor
protecting it from short circuits.
The serial interface uses non-inverted TTL logic levels: a level of 0 V corresponds to a value of 0, and
a level of 5 V corresponds to a value of 1. The input signal on the RX pin must reach at least 4 V to be
guaranteed to be read as high, but 3.3 V signals on RX typically work anyway.
The serial interface is asynchronous, meaning that the sender and receiver each independently time
the serial bits. The sender and receiver must be configured to use the same baud rate, which is
typically expressed in units of bits per second. The data format is 8 data bits, one stop bit, with no
parity, which is often expressed as 8-N-1. The diagram below depicts a typical serial byte:
Tic Stepper Motor Controller User’s Guide © 2001–2018 Pololu Corporation
4. Setting up the controller Page 32 of 150