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What is the relationship between RX and TX pins and the A1,A2,B2,B1 pins?

Hello, I’m trying to connect a micro stepper linear actuator to a Tic T825 that will be connected to a Arduino Uno. I’m trying to drive the motor using serial control. It’s suggested that I connect the RX pin to 10 and TX pin to 11. What I’m trying to figure out is what is the connection between RX, TX to the motor pins A1, A2, B2, B1? Like is RX for A1 and A2 and TX for B2 and B1?


I moved your post to the motor controllers/drivers and motors support category since it is more appropriate here.

The RX and TX pins do not connect or correlate directly to the motor outputs like your questions suggests. You can think of each Tic as having two main components, a microcontroller and a stepper motor driver. The RX and TX pins (as well as most of the other control interface pins except STEP and DIR) connect to the microcontroller on the Tic. When you use the Tic in serial mode, your Arduino and the microcontroller on the Tic communicate via serial protocol. (If you are using our Arduino library for the Tic, you can see a list of the available serial commands here.) Based on the commands your Arduino sends, the Tic’s microcontroller generates the STEP/DIR signals required to control the stepper motor driver accordingly. In the case of the Tic T825, the driver is the DRV8825, and that is what controls the motor outputs.

- Patrick

So would I have to connect the STEP and DIR pins on the Tic to the Arduino to control the motor?

The STEP and DIR pins should be left disconnected if you want to control the Tic and attached stepper motor through the Tic’s serial interface (or any of the other high-level control interfaces). As I described before, the microcontroller on the Tic will generate the signals the driver needs for you based on the commands you send it. You would only need to connect the STEP and DIR pins if you want to control your motor with that interface (in which case you would be bypassing the microcontroller); in all other control modes, STEP and DIR function as outputs instead of inputs.

You can find more information about how to set up the Tic for each control mode, including what connections are required, in the Tic Stepper Motor Controller User’s Guide which is available on each Tic’s product page under the “Resources” tab.

- Patrick

So do the motor pins A1, A2, B2, B1 correspond to any pin digital output pin on the Arduino? I’m still confused on what would be my digitalread pin and digitalwrite pin? Would I include the RX and TX pins (10 and 11 respectively) in the code?

No, the RX and TX pins do not connect or correlate directly to the motor outputs.

To control the Tic in serial mode you should not configure any of your Arduino pins to behave specifically as digital inputs or outputs; you just need to identify which pins you are going to use for RX and TX in serial communication.

In case you have not already, it might be helpful for you to look at the Setting up serial control section of the Tic user’s guide and the serial example programs from our Arduino library.

- Patrick