Controlling servos with PIC16F84A - Electronic Circuits Projects Diagrams Free

Ostekjeks · 24th February 2005, 08:39 PM

Firstly, I didn't exactly know where to post my topic, so please move it if necessary.

I'm planning to build a kind of motorized panning and tilting head for a camcorder crane, and apart from the main construction, this is what I?ve planned this far:

The camera unit is supposed to be controlled by two servos (modified to "motors" if necessary (especially the panning unit)). I'm hopefully using a PIC16F84A micro controller to control the two servos, unless this makes the project (even) more complicated. My problem is to find a way to accomplish this project. Since my programming skills are somewhat limited, I need help to program the micro controller, making it possible to control the servos via some kind of input. I have a compiler for the PicBasic programming language, if it would help anybody. I have also a modified servo for continuous rotating available, and I can modify another if that would be preferable. I already have a circuit from a robot (featured in the book "Insectronics" by Karl Williams I hopefully can use instead of using money and time constructing a new circuit. However, if anyone has suggestions to a very low-cost, extremely simple circuit to make it possible for the micro controller to communicate with the servos, please let me know. Since I already have an applicable circuit, it would be great if anyone could se if they could help me programming the micro controller to make the servos respond to a certain input (e.g. a simple switch). If you know the language, you can use the .bas-files at the page mentioned above to help you understand the circuit. The perfect solution to my project would be some sort of input-controls (pot-meters?) that makes it possible to determine the amount of rotation / rotation speed on the (prospective modified) servos.

I hope someone understands this jumble. If you have any questions, please ask me. Thanks in advance!

**Nigel Goodwin** · 25th February 2005, 07:56 AM

You don't want to modify the servo's, they are ideal for your purpose as they are - you can always increase the amount of movement by mechanical methods, although servos will generally move a good bit further than their specs actually say.

The only connections required from the PIC to the servo are a 0V connection and the input pulse to the servo, you then use the PIC to generate the require pulses to position the servo.

A simple google will find LOTS of sites showing you how to do this.

I would also suggest you use a more modern PIC, rather than the long obselete 16F84!.

Ostekjeks · 25th February 2005, 08:50 AM

I'm planning to use the 16F84 since I don't want to fund too many new components and equipment. Moreover, my programmer only accepts this chip. You say there are lots of sites concerning this topic, but since I left my interests in this a year ago, I probably need some help finding info. Feel free to post me links to sites with related projects.

By the way, how am I supposed to pan a camera (lets say nearly 180 degrees) with an unmodified servo? I can't figure out a solution that don't needs a lot of gears, which I really try to evade.

**Nigel Goodwin** · 25th February 2005, 10:06 AM

Quote:

Originally Posted by Ostekjeks

I'm planning to use the 16F84 since I don't want to fund too many new components and equipment. Moreover, my programmer only accepts this chip. You say there are lots of sites concerning this topic, but since I left my interests in this a year ago, I probably need some help finding info. Feel free to post me links to sites with related projects.

Have a look at http://www.eagleairaust.com.au/sampcode.htm which has a number of servo projects, you might also try http://www.theoldworkshop.freeserve.co.uk/index.htm. Or a quick google for '+servo +pic' produces loads of hits, including this one http://www.digitalnemesis.com/ash/pr...vo/default.htm

Quote:

By the way, how am I supposed to pan a camera (lets say nearly 180 degrees) with an unmodified servo? I can't figure out a solution that don't needs a lot of gears, which I really try to evade.

You can use a crank to extend the movement range, from a large diameter on the servo, to a smaller diameter on the target - this will give a larger movement on the target. Or use the servo movement to slide a rack, which rotates the camera via a gear. Or use a gear on the servo and a gear on the camera, or a chain drive with two sprockets?. You only need to extend the movement a small amount - servo's will commonly move far further than their spec says - it might even manage 180 degrees!, the positioning pot is capable of 270 degrees.

No solution is going to require more than two gears, which is hardly 'a lot of gears' :lol:

The advantages of using an unmodified servo far outweigh the slight mechanical difficulties - but test your servos first!, they might well move enough fed from a PIC.

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24th February 2005, 08:39 PM	(permalink)
Ostekjeks	Controlling servos with PIC16F84A Firstly, I didn't exactly know where to post my topic, so please move it if necessary. I'm planning to build a kind of motorized panning and tilting head for a camcorder crane, and apart from the main construction, this is what I?ve planned this far: The camera unit is supposed to be controlled by two servos (modified to "motors" if necessary (especially the panning unit)). I'm hopefully using a PIC16F84A micro controller to control the two servos, unless this makes the project (even) more complicated. My problem is to find a way to accomplish this project. Since my programming skills are somewhat limited, I need help to program the micro controller, making it possible to control the servos via some kind of input. I have a compiler for the PicBasic programming language, if it would help anybody. I have also a modified servo for continuous rotating available, and I can modify another if that would be preferable. I already have a circuit from a robot (featured in the book "Insectronics" by Karl Williams I hopefully can use instead of using money and time constructing a new circuit. However, if anyone has suggestions to a very low-cost, extremely simple circuit to make it possible for the micro controller to communicate with the servos, please let me know. Since I already have an applicable circuit, it would be great if anyone could se if they could help me programming the micro controller to make the servos respond to a certain input (e.g. a simple switch). If you know the language, you can use the .bas-files at the page mentioned above to help you understand the circuit. The perfect solution to my project would be some sort of input-controls (pot-meters?) that makes it possible to determine the amount of rotation / rotation speed on the (prospective modified) servos. I hope someone understands this jumble. If you have any questions, please ask me. Thanks in advance!

25th February 2005, 07:56 AM	(permalink)
Nigel Goodwin	You don't want to modify the servo's, they are ideal for your purpose as they are - you can always increase the amount of movement by mechanical methods, although servos will generally move a good bit further than their specs actually say. The only connections required from the PIC to the servo are a 0V connection and the input pulse to the servo, you then use the PIC to generate the require pulses to position the servo. A simple google will find LOTS of sites showing you how to do this. I would also suggest you use a more modern PIC, rather than the long obselete 16F84!. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

25th February 2005, 08:50 AM	(permalink)
Ostekjeks	I'm planning to use the 16F84 since I don't want to fund too many new components and equipment. Moreover, my programmer only accepts this chip. You say there are lots of sites concerning this topic, but since I left my interests in this a year ago, I probably need some help finding info. Feel free to post me links to sites with related projects. By the way, how am I supposed to pan a camera (lets say nearly 180 degrees) with an unmodified servo? I can't figure out a solution that don't needs a lot of gears, which I really try to evade.