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Hb-25 Ramping

Assistance Requested

Help Ellis with their question and receive $10 of EZ-Credit to get more robots and parts from our store. The following information was provided about their previous efforts searching tutorials for a resolution.

Ellis claims to have checked these sources:

I need some help on something.

I have two Parallax HB-25 motor controllers. I have been working on getting them to start and stop smoother. They right now are jerky in starting and stopping. I contacted Parallax customer service with my problem. I am using an EZ-Bv4 microcontroller to drive the HBs.

Here is my question and answer from Parallax:

I am running two HB-25 with your aluminum mount and wheel kit that I purchased from your company I have them connected to an EZ-Builder microcontroller. I would like to know if these motors can be ramped. When they start up they jerk. I would like to make them startup easier and smoother. If yes do you have code that you can send me so I can code the software I am now using. By the way the HB-25s are awesome. They are very quiet.Ellis,

Parallax answer:

If they're jerking then that means they're getting a pulse value for a fast speed before they get one for slow speed. If you update the pulse from 1.5 ms toward 1 or 2 ms then the motors will ramp just fine. In fact, the demo code we have for the HB-25 (BASIC Stamp) smooth ramps up in one direction and then back down and does the same in the other direction.

Chris Savage
Engineering Tech, Parallax Inc.

My problem is that Parallax always talks in ms when talking about their controller. I guess I am understanding this right that with most servos 1ms is reverse and 1.5ms is stop and 2ms is forward. How would I code this so the EZ-Bv4 could send the right signal to the HBs so they would not jerk when starting and stopping? I think I am right that EZ-Builder software does not use ms in their coding like Parallax does.

I am learning so anything you can tell me would be greatly appreciated.


I have found a few conversations, tutorials and activities that may help with your question. Take a look at these links. I've sorted them by what I believe to be most relevant but that is not always the case as I'm still learning.

Also, consider reviewing the Learn section for informative lessons and activities. Check it out!


I believe those controllers work the same way as Modified Servos. The Modified Servo controls should work with them as should the ramping script I posted yesterday.

If memory serves me correctly there is an init sequence needed for these too. This was discussed a few weeks ago and Jeremie posted the required ez-script. A quick forum search should find the topic.

FYI: 1ms is Servo position 1, 1.5ms is 90 and 2ms is 180.


Rich thank you for the conversion. I already used the info provided earlier for the initialization of the HBs. I will look for the ramping shared earlier.



Thanks for all the help. You really do make a great effort to help people.