p.p.m to p.w.m conversion

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toejam
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p.p.m to p.w.m conversion

Post by toejam » Sat Dec 15, 2001 4:27 am

hi,
T'm looking for a way to convert the servo output of an r.c. reciever to p.w.m to control the foward and reverse speed of a motor.Instead of using an h bridge i want to use a relay to reverse the motor. The speed must be ramped up with an adjustable rate.I think a pic would handle this but am lacking in this area thanks, jim

James Cart
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Re: p.p.m to p.w.m conversion

Post by James Cart » Tue Dec 18, 2001 5:59 pm

Hi Toejam,
I don't have any URL's handy, but do a search for RC car speed controllers. There are plenty of examples for the PIC micro, schematics, source code and all.
I have also seen simple analog controllers schematics that can do the same thing. I fooled around one afternoon with an analog speed controller, it was easy to breadboard and worked suitably well.
On the ramping, it sounds like that is best done on the transmitter end. The coding could get a little sticky if your not that experienced.
regards,
James

toejam
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Re: p.p.m to p.w.m conversion

Post by toejam » Thu Dec 20, 2001 12:27 am

Thanks for that info,James.I just finished researching that before i posted this question.There were many sites listed but none seemed to be responding.I did find one analog version but no leads reguarding the use of pics.It seems like any information related to that subject has been erased.

josmith
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Re: p.p.m to p.w.m conversion

Post by josmith » Sat Dec 29, 2001 2:17 pm

I haven't actually tried this conversion on a stamp but just about anything on a stamp is easy. <p>It has commands like pulsein to read the length of the incoming pulse and pulseout to send the conditioned pulse to your amp.Use either math or a lookup table in between. It also has a pwm output but it's more for controlling an analog voltage. Download stamp.exe and the documentation free form www.parallaxinc.com. Make your own programming cable and you'll just have to buy the stamp itself.

toejam
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Re: p.p.m to p.w.m conversion

Post by toejam » Tue Jan 08, 2002 6:29 am

thank you joesmith. that is an great website.I've still been lookin around and came up with some info in seattlerobotics.org on servo modification.The neat part is the hardware design gives me good insight about possable programs for the stamp.Now to get down to basics whew!!

toejam
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Re: p.p.m to p.w.m conversion

Post by toejam » Tue Jan 08, 2002 6:30 am

thank you joesmith. that is an great website.I've still been lookin around and came up with some info in seattlerobotics.org on servo modification.The neat part is the hardware design gives me good insight about possable programs for the stamp.Now to get down to basics whew!!

toejam
Posts: 253
Joined: Wed Dec 05, 2001 1:01 am
Location: n.c.
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Re: p.p.m to p.w.m conversion

Post by toejam » Tue Jan 08, 2002 6:31 am

thank you joesmith. that is an great website.I've still been lookin around and came up with some info in seattlerobotics.org on servo modification.The neat part is the hardware design gives me good insight about possable programs for the stamp.Now to get down to basics whew!!

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