Servo control?

**h3rk** · 09-16-2008, 10:43 PM

Originally Posted by JayinMI

Upon searching for a while, I found the Aircon2 by Mastero. From the sounds of it, it would do what I want, which is to control servos attached to the HVAC mechanisms to change temp and output position. The mechanical part makes perfect sense to me. I understand I need some sort of PWM output to control a servo, to do what I want and as I understand it, the FB doesn't off this natively. Also, Mastero seems to have disappeared from the board, or at least I haven't seen any recent posts. Since the FB does a bunch of other stuff I want (not relating to HVAC controls) I will probably go this way.

Has anyone figured out how to do this yet? I know H3rk was working on something similar, but he's taking it to the nth level compared to what I need.

I follow alot of what's going on, but the last time I programmed anything was when I could still program in BASIC or Assembly on my TRS-80 Color Computer 2/3's.

So, some of the software stuff is over my head.

But I have time to learn.

Thanks.

Jay

Yeah, no PWM/ Analog servo support yet. But no worries...

If you don't mind chebby parts in your Slopar, there are some ac delco servos that will operate with just 3 voltages, (only needs 2 digital outputs, and a voltage divider). They will drive in a particular direction as long as the corresponding voltage is present. They also have an analog output (position sensing potentiometer) for feedback. Controlling a servo like this from a fusion brain is no-sweat. Knowing whether or not it will work for you, really depends on the mechanical (space, shaft, etc.) aspects. There's more about it in the Auto HVAC thread. I really should clean that thread up, maybe put it in a easier to read categorized format, put more info for different apps, in a new thread...

I'll be happy to help if I can with your application. I'm happy to support anyone with going to the n-Xth level, if I can.

**JayinMI** · 09-17-2008, 01:32 AM

Originally Posted by h3rk

Yeah, no PWM/ Analog servo support yet. But no worries...

If you don't mind chebby parts in your Slopar, there are some ac delco servos that will operate with just 3 voltages, (only needs 2 digital outputs, and a voltage divider). They will drive in a particular direction as long as the corresponding voltage is present. They also have an analog output (position sensing potentiometer) for feedback. Controlling a servo like this from a fusion brain is no-sweat. Knowing whether or not it will work for you, really depends on the mechanical (space, shaft, etc.) aspects. There's more about it in the Auto HVAC thread. I really should clean that thread up, maybe put it in a easier to read categorized format, put more info for different apps, in a new thread...

I'll be happy to help if I can with your application. I'm happy to support anyone with going to the n-Xth level, if I can.

As long as they're not Ford parts, I don't care

I'd be interested to see those. I have some left over servos from some RC car stuff I was planning to use, but I'm not locked into them. I go to the Junkyard about every other weekend, so if I knew what they came out of, I could grab some.

On the up side, I don't have any vacuum stuff on my HVAC controls.

Jay

**h3rk** · 09-17-2008, 01:42 AM

Vacuum's easy too but as for the servos,

They look like this:
http://info.rockauto.com/ACDelco/Det...ml?15-5660.jpg

5 pins, 12V, GND, sensor GND, Feedback, Control (5V= open, 2.5V = hold, 0V = close). That way you don't have to control the servo with variable analog output, you just use variable analog feedback.

It's about 1.3" wide 4"x3" (not exact, I have a couple I can take better pictures of if you want).

Many newer chevy trucks have them. And many cars too.

There are versions without feedback though, so be careful. But they could be used for people who need them for recirc.

The rotating sleeve is splined....

**h3rk** · 09-17-2008, 01:49 AM

Also, I'll take one and build a quickie example skin of how to control it. I'll video it, showing how to hookup, and measure the range of motion. Probably later this week or weekend sometime. There's someone else I've shown these to that it might help them see if it works for them too. I'd hate to run someone up the wrong tree. But theoretically, it's a great solution for servo via fusion.

**JayinMI** · 09-17-2008, 01:59 AM

Originally Posted by h3rk

Vacuum's easy too but as for the servos,

They look like this:
http://info.rockauto.com/ACDelco/Det...ml?15-5660.jpg

5 pins, 12V, GND, sensor GND, Feedback, Control (5V= open, 2.5V = hold, 0V = close). That way you don't have to control the servo with variable analog output, you just use variable analog feedback.

It's about 1.3" wide 4"x3" (not exact, I have a couple I can take better pictures of if you want).

Many newer chevy trucks have them. And many cars too.

There are versions without feedback though, so be careful. But they could be used for people who need them for recirc.

The rotating sleeve is splined....

So, would I just shoot 5V to it to move up from one option to the next and then give it 2.5V to keep it there, and 0V to close it? Or does it pass resistance on the feedback terminal to determine position?

I'm curious.

Jay

**h3rk** · 09-17-2008, 02:14 AM

5V makes it move continuously in one direction, 0V makes it continuously move in the other*, 2.5V holds it... That part I think you got.
So let's say your feedback signal (0-5V, or 0-100%) is at 50% (servo is holding there with 2.5V applied to it),

the skin will look at that feedback potentiometer and compare it to where your settings want it to be. Let's say your settings want it to be at 25%.

Then the skin will open digital outputs, putting 0V on the servo until it moves from 50% to 25%,

once it hits 25% the skin puts 2.5V back on the servo (by turning a digital output on), and holds it there.

**Rob Withey** · 09-17-2008, 02:18 AM

A teaser:

Code here : http://www.digital-car.co.uk/forum/s...5&postcount=33

Give me credit if you use the code.

**JayinMI** · 09-17-2008, 02:31 AM

Originally Posted by h3rk

5V makes it move continuously in one direction, 0V makes it continuously move in the other*, 2.5V holds it... That part I think you got.
So let's say your feedback signal (0-5V, or 0-100%) is at 50% (servo is holding there with 2.5V applied to it),

the skin will look at that feedback potentiometer and compare it to where your settings want it to be. Let's say your settings want it to be at 25%.

Then the skin will open digital outputs, putting 0V on the servo until it moves from 50% to 25%,

once it hits 25% the skin puts 2.5V back on the servo (by turning a digital output on), and holds it there.

OK, that actually makes more sense that my way

I was thinking it might be like this after I posted.

So, if I marked the positions of the arm for the flapper door (with the mechanical system still intact) on the housing, then I could determine percentage of each position from that. So, if there are 8 positions, then each would be 12.5% (0, .625v, 1.250, etc...) or something like that. Then I would just check the feedback position to match that voltage? That makes sense. Thanks!

Jay

**h3rk** · 09-17-2008, 02:42 AM

Originally Posted by Rob Withey

A teaser:

Code here : http://www.digital-car.co.uk/forum/s...5&postcount=33

Give me credit if you use the code.

I admire your skills. So that's a custom computer power supply with all of those added features? Heavy duty custom. And rather small, considering.

I probably need to give it a more thorough lookover though, to really understand what it is, if I'm off.

Originally Posted by JayinMI

OK, that actually makes more sense that my way

I was thinking it might be like this after I posted.

So, if I marked the positions of the arm for the flapper door (with the mechanical system still intact) on the housing, then I could determine percentage of each position from that. So, if there are 8 positions, then each would be 12.5% (0, .625v, 1.250, etc...) or something like that. Then I would just check the feedback position to match that voltage? That makes sense. Thanks!

Jay

Just about along those lines. It's nice and simple. It's just that the servo isn't necessarily RC car size. It's made for this application. But may be to big for the little neon, and its underdash. Also the shaft/spline mating is something to consider... I might make a mold of it, and make little plastic inserts if people end up using it.

**JayinMI** · 09-17-2008, 02:50 AM

I've been playing with cars for almost 20 years, and I've been installing car audio for about 15. Mechanical stuff I can figure out. If it comes to it, I plan to rebuild the whole dash anyway. I can make room for a servo, but I've had the dash apart of my other Neon (this is my third) and there should be plenty of room. Matching up the splines, I'm not worried about. The electronics and programming end, is a little more difficult for me. Especially since I use a Mac and will have to dust off my PC to work with the FB.

Jay