Circuit Design Help

bl3nd3r · 06-22-2006, 12:15 AM

Hello everyone. I am in the process of trying to design a circuit for controlling a motor and needed some help. What I am hoping to do is creat a board that can control a motor and allow the position of the memory to be stored for the next power up. It will be used to control a motorized screen I am working on. So what I need to know is what components I will need and if this is feasible/already exists. The problem I am running into is I have no idea what it would be called.

I have included a very basic diagram of what the circuit will do. Your help is greatly appreciated.

pRoFiT · 06-22-2006, 12:17 AM

Why not use a pic16f84 with Led sensors for position, two DPDT relays for motor direction and a switch to change up position to down position.

p.s. love the diagram

0l33l · 06-22-2006, 12:17 AM

Look into phidgets.

bl3nd3r · 06-22-2006, 12:25 AM

Quote: Originally Posted by pRoFiT

Why not use a pic16f84 with Led sensors for position, two DPDT relays for motor direction and a switch to change up position to down position.

p.s. love the diagram

Okay so the PIC would allow me to store code for the whole unit and would be able to tell the motor to reset to the previous position using input from the LED sensors? Also would you happen to know of a good place to get these items (maybe as samples) or model numbers? Thanks for the reply.

p.s. I thought people might like it. Not everyday do you see such awesome paint skills.

bl3nd3r · 06-22-2006, 12:27 AM

Quote: Originally Posted by 0l33l

Look into phidgets.

I have been looking at the phidgets lineup and actually am working on ordering one of the USB servo controllers tommorow. I didn't know if they could control motors or not or if it would be the right part for what i hope to do. Also another problem with this option is that I would have to wait for the PC to boot before the motor settings would load.

I guess that would be a good way to see that my computer is ready though....

momanz · 06-22-2006, 12:35 AM

http://www.glitchbuster.com/

Randy is fast, has good shipping rates and extremely helpful. You can store data to the EEPROM on a PIC pretty easily. you can also use a PIC to control a stepper motor which would probably be the best way to control a motorized screen. Do a search on PICs and robots/robotics for ideas.

2k1Toaster · 06-22-2006, 12:43 AM

Well if you know that the input voltage will be the same, then just build a simple timer circuit with a small pot or something so you can adjust it once and never mess with again, until motor starts to wear out, and you need to up the time. Something like a counter circuit that runs off some 555 or something, and maybe an analog to digital from the pot to the value you want to count up to.

Well for your idea with the memory, most easily available memory is volatile, so there has to be some voltage through it. I can try to look up some compatable chips, but I'm sure you know about all that. You could just use some CMOS shift registers as long as there will always be power.

Or just place some conductive contacts. Stationary at the beginning, and at the end of the track, and then an adjustable one to stop the position. Would make it an even simpler circuit. Start sliding motor until contact 2, then rotate motor until contact 3.

bl3nd3r · 06-22-2006, 01:00 AM

Quote: Originally Posted by 2k1Toaster

Well if you know that the input voltage will be the same, then just build a simple timer circuit with a small pot or something so you can adjust it once and never mess with again, until motor starts to wear out, and you need to up the time. Something like a counter circuit that runs off some 555 or something, and maybe an analog to digital from the pot to the value you want to count up to.

Or just place some conductive contacts. Stationary at the beginning, and at the end of the track, and then an adjustable one to stop the position. Would make it an even simpler circuit. Start sliding motor until contact 2, then rotate motor until contact 3.

Just to clarify I was hoping to be able to get the servo to, upon power move back to the last position it was at (before being turned off) and on power down reset to an "off" position. Also I want to be able to have multiple angles for the screen so I can choose whatever angle will work best.

2k1Toaster · 06-22-2006, 01:17 AM

Well it will never truley be "off", just in standby, constantly powering the memory and wating for a signal (pushbutton?) to activate. Then toggle some flip flop from 0 (off) to 1 (on). Then have some logic saying: when "TFF is 1" AND "Screen is not out" (Contact 2 shorted), power push out motor. Then when it shorts it stops. Then have when "Contact 2 is pushed" AND "TFF is 1" AND "Screen is not open", give an enable signal. Then that enable signal feeds into something that has a pot connected to an A2D so the more resistance the pot is giving, the higher the digital value, meaning the longer the signal is allowed to carry, so the screen flips up longer. Or have it go until a predetermined contact is shorted and then plus or minus the adjustments.

Your design not mine, but that uses very simple logic and should be easy to implement.

2k1Toaster · 06-22-2006, 01:18 AM

How much do you know about electronics btw?

bl3nd3r · 06-22-2006, 01:24 AM

Quote: Originally Posted by 2k1Toaster

How much do you know about electronics btw?

I myself have a limited knowledge of electronics but am able to follow what you are saying. Also for implementation and the such my dad is quite knowledgable about electronics as he works with medical electronics. He is able to help me out with most things I have trouble with, which is very helpful.

2k1Toaster · 06-22-2006, 01:25 AM

Is what I said similar to what you are looking for?

bl3nd3r · 06-22-2006, 01:33 AM

Yeah your plan does seem to be a good solution. I would just have to determine what components I needed for that to work. Also do you think it would be easier just to use a USB servo controller for this project? What it would do is have a piece of code that runs when the computer loads and tells the servo to turn on for a specific time. In your opinion would you want to wait till the computer is booted for the screen to initiate?

2k1Toaster · 06-22-2006, 02:57 AM

I like seeing the BIOS and stuff pop up, so I actually have my monitor always on, (powersaving mode, but on). As soon as there is a signal, poof, it's onscreen. The lilliput hack thing didn't work on mine, but I don't have a lilliput, so no wonder!

As for whether to USB or not, that is up to you. Would you rather have to solder a circuit, or plug it in and code? Which do you feel more comfortable with? I personally wouldn't want to wait for the 20 seconds for windows to load, for it to be able to execute this program, but up to you. If windows freezes on boot, no screen. If you need the BIOS, no screen.

bl3nd3r · 06-22-2006, 10:04 AM

Quote: Originally Posted by 2k1Toaster

I personally wouldn't want to wait for the 20 seconds for windows to load, for it to be able to execute this program, but up to you. If windows freezes on boot, no screen. If you need the BIOS, no screen.

I would still be able to have the monitor one at all times even though I am using this system. The board would only be controlling the servo itself and not the power to the monitor. So as soon as there is a signal you would still see everything (including bios) but the actual tilting feature would be initiated with windows itself.

I have ordered a couple USB servo controllers and should be able to test them in the next couple weeks with this system. If it ends up sucking I will just end up checking out my other options.