HB-25 Question
ScottishCaptain
Posts: 10
Greetings to all.
I've got a robot that has some hefty motors on it. They basically require 500-1A running, and draw much much more then they jam/stall.
I'm thinking about using 4 HB-25 controllers, or 2 of them with the motors paired for the left/right side in parallel.
I've got some quick questions about these units.
First- I'm assuming this is possible but I don't know as the Parallax manual doesn't explicitly state it- can you control the motor speed (or power), via sending the HB-25 a specific pulse? Something similar to PWM, so that the motor isn't full-on 100% of the time.
And second- the unit's have fans on them. Parallax's manual states the idle current draw for each HB-25, and then the current with the fan on. Does the fan itself only turn on when the control IC hits a specific temperature? Or is it on all the time?
Cheers!
-S'Captain
I've got a robot that has some hefty motors on it. They basically require 500-1A running, and draw much much more then they jam/stall.
I'm thinking about using 4 HB-25 controllers, or 2 of them with the motors paired for the left/right side in parallel.
I've got some quick questions about these units.
First- I'm assuming this is possible but I don't know as the Parallax manual doesn't explicitly state it- can you control the motor speed (or power), via sending the HB-25 a specific pulse? Something similar to PWM, so that the motor isn't full-on 100% of the time.
And second- the unit's have fans on them. Parallax's manual states the idle current draw for each HB-25, and then the current with the fan on. Does the fan itself only turn on when the control IC hits a specific temperature? Or is it on all the time?
Cheers!
-S'Captain
Comments
Greetings·rough weather sailor!
Yes, the HB-25 receives pulses similar to servos - 1 ms is full speed CCW and 2 ms is full speed CW. That easy. With your small motors like you describe, you could put two motors on one HB-25. The HB-25s generate a servo style pulse. It's on for 1-2ms, then off for at least 20 ms. The only difference is that you need to send it only one pulse to set it (and forget it) to allow the HB-25's chip to be set a single time with a speed/direction, or you could send them over and over again if you wanted to.· The fan turns on whenever you've got power to the HB-25s - so it's on all the time.
You could manage much larger motors with these controllers, by the way. These motors are drawing 10-20 A at 12V:
·
Ken Gracey
Parallax, Inc.
Post Edited (Ken Gracey (Parallax)) : 10/22/2006 8:09:38 PM GMT
When you say that 1ms is full CCW and 2ms is full CW, is it possible to set it to run at like half-CCW speeds (or power, I guess)? Would that be sending it a 0.5ms pulse for example, or a 1.5ms pulse for half-CW Speeds? (That's the only logical conclusion I can think of, since I've never played with Servo's like this before).
The particular robot I'm building needs to be "house-trained", and as it is the platform I want to use (Lynx Motion 4WD3) runs at over 45"/second, which is a bit fast for my use as I'd hate to see it crash into a drywall at this speed. That's why I need to know if it will run slower when required to.
Nice robot, btw. Looks like a heavy little beast!.
-S'Captain
- Ken
That's what I needed to know.
Cheers!
-S'Captain