Society of Robots - Robot Forum
Mechanics and Construction => Mechanics and Construction => Topic started by: kurtron9000 on May 28, 2008, 07:32:58 PM
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AHHH!!! So i basically I've been putting off this Mod to the very end. When I plug my servo into the servo bus and flip my battery switch on they do a quick little rotation and that is it. When I programmed my microcontroller with everything hooked up at the completion which went surprisenly fine it did the same little rotation. So I think I'm close to being finished the last thing is this Mod that is driving me crazy. I bought the HiTech HS-425 BB. When I open it up though I got totally lost. First, do i need to reprogram my microcontroller to make it use the hex file and erase everything else. Second when i turn the swith on with the gears out it dosen't spin freely. And third I don't see any thing that is making it stop and even if it was it rotates in the same direction each time. I hope all this makes sense to someone. PLEASE HELP MEEEE!!!!!
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Hi kurtron!
I have some questions:
I'm assuming you are trying to mod your servo for continuous rotation?
When you turn on the power, the servo moves a bit in one direction?
If you turn on and off power a couple of times, can you make the servo spin a whole 360 degrees?
Have you created functioning code for a servo controller before the mod? Or is it possible it's a software error?
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YES Sixringz you're awesome, so yeah im tryin to mod it for continous rotation. Yes it rotates just a little bit each time. but no I haven't downloaded anything to make it rotate continously. Is that the Hex file that is in the servo modify tutorial? I did program it with the three files from Step 4. That's when the servo's did a little rotation after the microcontroller got finished and at first i was excited but now i'm wondering if something is wrong. Should I just delete the microcontroller and download the servo mod hx file? thanks again for the help man.
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Well, I haven't actually modified any servos for continuous rotation myself since I found Parallax have servos already made for that and they're not high priced. But I've worked alot with regular servos and read a bit of the tutorial now real quickly, so I think I can help you somewhat anyhow. First of all, the hex file is for the controller sending a 1.5ms pulse to the servo to keep it centered. The file is intended for the Atmega8 MCU so if you are using any other microcontroller you may need to create and compile your own file proper to your controller. (Especially if you're not using AVR) Most servos use 40 Hz which means you should supply the servo with a new signal every 1/40 = 0,025 = 25ms. Don't worry though, the servos aren't that picky, you can get away with lower speeds and sometimes even a bit higher. (keep it lower rather than higher though)
This setup should work:
1.5ms 25ms
__----------___________________-----------_________________------------_________
So, make sure you have a centering .hex file for your servo before you go to the steps in the tutorial. Tip: If you are using AVR there's a function in util/delays.h called _delay_ms();
#include<util/delay.h>
....
....
_delay_ms(#amount of ms you want);
...
...
Hope this helps.
/Nicky
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That servo twitching is just from electrical noise created when you flip the power on.
Should I just delete the microcontroller and download the servo mod hx file?yeap!