Polite stop / kill / reset for Tic825?

I am new to Tic’s but have a fair bit of experience with steppers and drivers. I am currently trying to use a Tic825 (and others later) as a stand alone controller in “Encoder Speed” mode (e.g. power supply, Tic, encoder and a stepper, no micro controller or other external communication). I have set it up to allow the encoder to turn the stepper both CW and CCW rotation.

I have two problems:

  1. I can’t figure out what the ideal setting is for the postscaler so that when I return the encoder to a “neutral” position, it actually stops the motor moving. Playing around I found some values (multiples) that seemed to stop sending steps, but it wasn’t obvious why it worked, or what value(s) would be appropriate.

My prescaler for this particular encoder is set at 1, even though it has detents, it appears to just be a 1 count per detent encoder. My max speed for this particular application is 70,000,000 (7,000 pps).

Can you give me a better idea how to pick a value other than “approximately one hundredth of max speed” that results in an even division and halted motion?

  1. The bigger issue is that if the encoder is rotated quickly (I can’t control what an end user might do), and the Tic misses a count or more, the “stopped” encoder count might be off by some number of counts, which seems to create soft start errors in some conditions. These are not easily recoverable in a “black box” stand alone application, so I’m trying to figure out the best approach to make the system bullet proof.

If I connect a pushbutton to the Tic, it seems like I can choose “Kill” or “Reset” as possible options.

“Kill” seems to stop the motion, but doesn’t reset the encoder count (to 0), so it doesn’t always eliminate the soft error conditions.

“Reset” seems like it solves the encoder problem, by resetting the encoder count along with the entire processor, which does eliminate the soft start errors too.

Is it ok, or recommended good practice, to use a pushbutton as a “Reset” like this, or is there some better approach I’m not finding in the documentation?



I am sorry to hear that you are having trouble with the Tic T825.

If you have not done so already, I recommend reading the “Encoder input handling” section of the Tic user’s guide.

For your first issue, the exact value of the postscaler should not cause the issue you are seeing. I suspect you are seeing something like the following: if you turn the encoder too far in the positive direction, eventually the Tic stops increasing the “Input after scaling” variable, because increasing it would put it out of the range defined by the “Target maximum” or “Target minimum” settings. Then when you start turning the encoder in the negative direction, the “Input after scaling” variable immediately starts decreasing, so when you get back to the starting position, it will be less than zero. Is that what is happening? If not, can you post your Tic settings file here (which you can save from the File menu) and provide details about how you are testing the Tic and what is going wrong?

For your bigger issue, I am not sure what you mean by “soft start error”. The Tic has concepts of a “soft error” and a “safe start violation”. If you provide a screenshot of the Status tab of the Tic Control Center, that might help. Using a switch to reset the Tic with its RST pin or cut the power to VIN are both valid ways to clear the encoder count.


Thanks David. After experimenting with this for a few more hours I have a better feeling for the permutations and scenarios.

I think your suspicion on the first issue is what I was seeing, the effect of the encoder continuing to count beyond the target max / min. Thanks for that. I have experimented enough to understand how that works now.

The second issue isn’t as easy now. Sorry that I wrote my question when I wasn’t in front of the bench computer to use the right term, the issue is with the “safe start violation”. If I could use a push-button for a reset, that would solve part of the problem. But because this will be part of a mechanical system with inertia (and mass), and I’d like to decelerate rather than halt abruptly, the reset is too violent. But it does reset the encoder count to zero.

When I tried using the RC pin as a “Kill switch,” that gives the desired deceleration behavior, but doesn’t reset the encoder count. That results in a, “Motor holding because of a safe start violation. Center the input.” Of course with my stand alone configuration there is no way to explain that to the end user. On the bench I can see in the Tic Control Center that the encoder needs to move one way or the other, back to zero, then the system works again. I don’t see any way to convey that in a stand alone controller.

Is there away to initiate a reset, or zero the encoder count, after a Kill switch operation?

I thought maybe the “Disable safe start” option in the Miscellaneous tab would help, but that just immediately returns the motor to the prior speed (same encoder count), so that won’t work.

Ideas? Suggestions?



For your first issue, if you are not happy with that behavior, your might consider increasing “Target maximum” and decreasing “Target minimum”, and relying on the “Max speed” parameter to limit the speed of your motor.

For the second issue, there is no way to achieve what you are asking for with a normal Tic. However, I have prepared a custom version of the firmware for you that makes the Tic clear the encoder counts whenever a kill switch is pressed:


This firmware version is called 1.07ce, and you can follow the instructions in the “Upgrading firmware” section of the Tic user’s guide to load it onto your Tic.


First of all, thank you very much for the custom firmware. It works beautifully, and does exactly what I needed to do.

I also experimented with your suggestion of not having the target matching max speed, and that is interesting in that the encoder does continue to increment, but has no effect on the velocity once the it hits the max speed. Unexpected, but useful. That sort of solves the return to zero issue I first encountered (but didn’t understand at the time).

Case closed, problem solved. Thank you very much.


That said… Somewhat unrelated, but I think there is an issue with the “Upgrade firmware…” process. I’m using Windows 10 Pro and Tic Control Center 1.8.0. If I choose “Upgrade firmware…” from the menu, and click OK to proceed, there is no way out except to install some version of firmware. (I understand why, and what’s going on, but this is likely confusing to those less familiar with firmware.)

What is misleading is that once I am presented with the “Browse” window / dialog, there is an “X” to close the window / dialog. But closing that window / dialog puts the Tic into a non-usable state, until some firmware file is chosen and installed. In other words, closing the window / dialog is not actually canceling the install (meaning it really should be a dialog with no option to close it).

Likewise, if a firmware file is selected and the “Program” button is clicked, the user is presented with a subsequent dialog asking if they are sure they want to proceed? That dialog has an option to “Cancel”, which by this time isn’t really an option. Rather I should say it is a misleading option. Canceling exits to a non-usable state as above.

I am glad the new firmware is working for you!

If you change your mind about upgrading the Tic’s firmware, you can power cycle the Tic or use its RST pin to get it out of bootloader mode. The firmware on the Tic does not get erased until you actually click “Program” and confirm you want to proceed.


Thanks for the power cycle tip. I didn’t try that one.


Will this work on the Tic 36v4 also?

Yes, it should.