Modifying electric wheel chair controllercfor PWM. ??? HIP4082IP ???
Tech-Man
Posts: 100
I may have said it already but I got an electric wheel chair for $25·at junk store. With insanely strong motors. I have a few project ideas electric car, Segway, weld it to a bike.
But first I need to either build new or modify the existing control circuitry to work with a basic stamp. Currently you can control it just fine with the little joystick but if I can figure out a way to do it with PWM it would be a lot easier to use in projects.
I was looking at the board and found an interesting part HIP4082IP I looked it up and found that its some sort of fet driver for h-bridges. I don’t know much about h-bridges or fets but I do know enough to know that they are the main control parts for the high power. ·On the PDF datasheet ·page 3 there is a fairly simple schematic for an h-bridge and it says something about PWM mode switching. Is this simply PWM input or is there much more to it, can’t be that easy. I tried to understand the pin outs on page 6 but I got lost. http://www.intersil.com/data/fn/fn3676.pdf
The way I figure it I should already have all the parts I need on the wheel chair controller. I could just unsolder the ones I need and put them on a perf board. Or maybe there’s a way to “insert” my PWM signal somewhere on the existing board, thats crazy i know but i guess it could be posible. ·
I’m hoping someone has herd of this part or has a good understanding of PWM h-bridges. Something I need to do a lot more research on. I understand the concepts pretty well it’s just all the different parts and values confuse the Smile out of me.
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There are no Undo buttons in life.
But first I need to either build new or modify the existing control circuitry to work with a basic stamp. Currently you can control it just fine with the little joystick but if I can figure out a way to do it with PWM it would be a lot easier to use in projects.
I was looking at the board and found an interesting part HIP4082IP I looked it up and found that its some sort of fet driver for h-bridges. I don’t know much about h-bridges or fets but I do know enough to know that they are the main control parts for the high power. ·On the PDF datasheet ·page 3 there is a fairly simple schematic for an h-bridge and it says something about PWM mode switching. Is this simply PWM input or is there much more to it, can’t be that easy. I tried to understand the pin outs on page 6 but I got lost. http://www.intersil.com/data/fn/fn3676.pdf
The way I figure it I should already have all the parts I need on the wheel chair controller. I could just unsolder the ones I need and put them on a perf board. Or maybe there’s a way to “insert” my PWM signal somewhere on the existing board, thats crazy i know but i guess it could be posible. ·
I’m hoping someone has herd of this part or has a good understanding of PWM h-bridges. Something I need to do a lot more research on. I understand the concepts pretty well it’s just all the different parts and values confuse the Smile out of me.
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There are no Undo buttons in life.
1151 x 1536 - 476K
Comments
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- Stephen
http://parallax.com/Portals/0/Downloads/docs/cols/nv/vol2/col/nv52.pdf
From what I can tell I should be able to use my HIP4082IP chips in the same configuration as they used the HIP4081A chips. But that means I would have to unsolder them from their original board and I run the risk of overheating them or something then I’m out a perfectly good (originally vary expensive) controller board.
So I just went and requested 2 samples of the HIP4081A chips. And if they decline my request, because I’m not a “Company” I can always just buy 2 of them for $3 something plus S&h no big deal.
The “big deal” at least to me is figuring out what FETs to get. I’m going to use that same schematic from the Nuts and Volts column most all the other parts are labeled. Except the Resistors they just say 51 I’m going to assume that’s ohms since it’s not marked otherwise? But I don’t want to assume because well… you know. ··Also the diodes across the FETs, they say 15V well what type. I’m guessing Zener because of the symbol. Or are they built into the FETs I think I may have read something about that.
But either way I have been combing that article plus a few other datasheets for a few days now and I can say that I understand the code for once. Well 98% of it. Once I looked at the code and made since of it I got the block diagram in my head all figured out. Though I still get hung up on part values and such.
I have yet to be formally taught this stuff and I think I’m doing pretty good, especially since I have reading disabilities and stuff that make it hard for me to comprehend written information sometimes. Let me tell you, if I had someone right beside me showing me this stuff first hand id have it down pat in a heart beat, but unfortunately I don’t. So I truly appreciate any and all help that has been given to me.
They used PWM xxx, xxx, xxx I’ve only ever used Pulsout so I looked it up in the help menu it’s so simple really. ·The first set is pin, then duty, and duration I also learned how it uses a capacitor. Really cool how it can “store” the voltage for the controller chip. Only question is where is the resistor and capacitor on this particular circuit? Must be inside the chip? If so ill have to see if I can find the specs and use them formulas I found to figure duty and dur.
As you might be able to tell I’m excited, I usually don’t end up figuring this stuff out I gust get lost. But I stared at the data sheet long enough and its happening. Also helps that this is a relatively simple circuit once I understood it.
Well still only about 95% on this but thanks.
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There are no Undo buttons in life.
Post Edited (Tech-Man) : 7/12/2008 3:33:17 AM GMT
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There are no Undo buttons in life.
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There are no Undo buttons in life.