Position Controller and HB-25 refresh

Greg Norton

Hello All,

When using the Parallax wheel kit and the HB-25 together, will the position controller allow the HB-25 to timeout on a long run? To clarify I'm considering running the HB-25 in the mode where a pulse is required at least every 4 seconds to keep the motor running. If I command the position controller to move a long way at slow speed will it refresh the pulses often enough to keep the motor going? I didn't see anything in the docs on the position controller one way or the other.

The idea is to use the lack of pulses to the HB-25 as an "uh-oh" signal and allow the HB-25 to timeout as a response.

Your thoughts are appreciated.

Greg

SRLM

You must not have looked hard enough. Look here on page 5.

Greg Norton

SRLM -

I am asking about the pulses that the position controller will send, not the response of the HB-25. The section you pointed me to describes the timeout feature which I understand and want to use. For example, if I command the motor to travel a distance that will require a 10 second run, will the controller send its programmed full speed pulse to the HB-25 and then wait until the desired position is reached before sending another (allowing the HB-25 to timeout because it hasn't received a pulse in 4 seconds)? Or will it periodically be refreshing the full speed command as it is traveling? It seems like my answer should be in the motor controller docs, not the HB-25 docs.

I am willing to bet that Parallax thought of this already, but I wanted to confirm.

Thanks for your help.
Greg

SRLM

Okay, now I get what you're doing... Do have an oscilliscope? If you do, then you can check to see if a pulse is being sent every couple of seconds. I'm guessing that it is, and that there is no easy way around it. You may be able to put some hardware on the HB-25 signal line that is attached to an I/O pin so that you uC can shunt the signal to ground. I'm not an electronics engineer (more of a software guy), so I can't design something like that, but it sounds reasonable.

Kevin McCullough

Hi Greg,

To answer your question, Position Controllers generate a continuous stream of pulses all the time - whether or not the pulses are changing value or staying the same. Upon power-up it begins generating the pulses (even before it receives a command to move), and continues to generate a new pulse every 20 ms.

Hope this clears up your question
-Kevin

Greg Norton

Yes, that's what I was trying to find out.

Thanks.

Greg