driving/stearing robot problem

[karlis]

since my robot wont use only 2 servos for driving and stearing i have a problem..

i build my robot on RC car, where i removed all rc stuff and puted on atmega16, and now starts my problem, 2 servo robot is simple, it use ir for driving/stearing.. but i have 1 for driving(farward/backward) and another one for stearing (left/right) servos got impulse from board, but what or where should i connect my 4 wires?

can i just connect them to ADC 0/1/2/3 ? or it will be hard in programming ?

[karlis]

i have another question, if this forum is related to robot electronics, why are so much views but no much less replays ? i would be glad to read some replay on my previeus question...

ps sorry for my bad language ..

[ed1380]

what 4 wires? you have 2 servos. where do the 2 new ones come from?

[karlis]

each servo have minimum 2 wires + & - ... i have 2 servos 2+2=4 wires..

should i post a picture of my robot for bether understanding ?

[JesseWelling]

Servos Generally need 3 wires. Ground, Signal, and Power.
The only one should should hook up to your micro is the Signal to your PWM pins.

Have you read the servo tutorial?
http://www.societyofrobots.com/actuators_servos.shtml

[karlis]

if you all didnt read my 1st post, or didnt understand my problem, i`ll try to explain something more...

i dont have usual servo.. i have simple old RC car, what i want to hook up to atmega16..  engine on this car have 2 wires +  & -
by changing polarity it changes direction.... hope you understand.. i`ll post a photo leater..

[Rebelgium]

If they only have two wires they're not servo's, they're probably DC motors with gears that look like servo's.
I've seen that in old RC cars before.

if you all didnt read my 1st post, or didnt understand my problem, i`ll try to explain something more...

You never said that clearly in your startpost, and don't nag about noone replying to your topic plz.

If they are DC motors, you'll need a DC motor driver.
do some research about them.

[karlis]

i`m sorry, i`m trying very much to explain as much as i can, but as you all can see my english knowlages aint realy good...

here is an photo of my robot http://img512.imageshack.us/img512/9821/robogy8.jpg

[AndrewM]

A picture says a thousand words.  You have two DC motors for control of your robot.  You can't (or at least shouldn't) hook the motors up to the controller.  You will need to put in an H-Bridge to control the motors, or even a cheap Electronic Speed Controller (ESC).

[karlis]

then i have 1 more question - how work servo's ? they are allso DC motors so why i couldnt connect them to chip ?

[AndrewM]

Servos = DC motors with built in gearing AND built in PWM control, which is why a servo has three leads.  Power to a servo is not supplied through your processor, it comes in on two of the three lines.  The third line for a servo is the PWM signal from your mcu.

What you have are two DC motors and you can't (shouldn't) power the motors straight from the mcu, you will fry your mcu.

[karlis]

oooh its sad news to me ... well i shal then order some servos ^_^