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Need some help on ESP32 and Tic T825 and md20b

I have an ESP32 connected to the Tic T825 and get the servo spinning one way only. When I send out a relative move negative, it actually moves 1 step in the positive direction. I changed the DIR pin and that did not seem to make a difference. I swapped in another servo and got the same behavior. I also tried a md20b and with that controller cannot get the servo to budge at all. On the md20b setup, it does not feel like the servo is getting any power (i.e. not holding) I have RST/SLP connected, GND to ESP GND and +5 to FLT. Any help or pointers to good videos/training would be appreciated. Thanks.


Just to clarify, the boards you are talking about control stepper motors, not servos.

The Tic T825 and the DRV8825 carrier are very different in terms of setup and use (even though they use the same driver), so it is difficult to troubleshoot both at the same time. Additionally, there is not a lot of information in your post about your actual setup or what you have done so far. I recommend reading through our “Support” page for some general tips and ways you can help us troubleshoot the system remotely (i.e. what kind of details are helpful).

After that, could you choose one of the boards to focus on first, and post more information about your setup? Good details to include are what stepper motor and power supply you are using, pictures of your setup that show all of your connections, and the simplest complete code that demonstrates the problem. Additionally, details about how the board is configured would be very helpful. For the Tic, you can simply post a copy of your settings file (which you can save from the “File” drop-down menu of the Tic Configuration Utility while it is connected), or for the DRV8825 carrier, this would include details about how you set the current limit and what voltage you measure at VREF.


Thanks, this really helped. Based on your comment, I watched the video on setting the voltage and that seemed to be my issue. I have it working now with the DRV8825 which is what I really wanted to use. I do have a couple of follow on questions.
Is the limiter for the DRV8825 the 2.2amp per coil? And if i have a stepper that is rated at 4.0amp would it be able to control that stepper? Would that be 2amp per coil?

Thanks again

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As we mention on the DRV8825 carrier product page that board can handle around 1.5A per phase continuously without additional cooling. So, unless you are using sufficient additional cooling, you should not set it any higher than this.

Stepper motor and stepper motor driver current ratings are both usually given as current per phase. You can sometimes get by with controlling a stepper motor at a lower current than it is rated for (which will give you reduced torque and speed capabilities), but controlling a 4A per phase stepper motor at 1.5A per phase is probably not going to work very well (especially if you specifically chose that motor for its power).

The only stepper motor driver that we carry that would be able to handle 4A per phase without additional cooling is the High-Power Stepper Motor Driver 36v4. However, please note that this driver requires an SPI interface to configure it each boot. We also have a Tic 36v4, which is a version of the Tic controllers that uses the same driver.


Thanks again Brandon! I did order a couple of those DRV8825s and will integrate those into my solution when they arrive.