mrs1 servo desperation

DutchBot

Hi guys,

I'm really stuck here. I'm using the MRS1 with a 3 ping setup (as the stingray) and things work fine. It roams the room and avoids objects. So at first glance it seems ok.

Now I would like to add some servo's. For testing I just use the servo32.spin something script. But whatever I try I can't get the servos to function in the right way. It jitters but thats about it. I tried adding a resistor to the signal wire and swapped arround servo's. Seems that some respond "little" better then others but never do they work fine.

I then thought it could be some noise caused by the powersupply (there is not much more else on the robot) so I took out a breadboard and seperated the signal wires from the power wires. Still the same. I guess that tells me that the noise is on the actual signal wire either caused by the MRS1 or by the servo's.

I tried the servo's on a picaxe and no problems there. Is there anyway I can trouble shoot this without an oscilloscope or do I have to start saving for one?

Thanks a ton!

DutchBot

Kye

Its probably brown outs... You may need a low pass filter like on the propeller proto board to handle the servo current draw.

prof_braino

n00b question:
Can there be a separate power supply for the servos, and just connect the ground? For example, a wallwart for the prop chip, and a bench supply for the servos in testing, and in the final application a small battery pack for the propand BIG battery pack for the servos? If so, do these need filtering?

Ravenkallen

@Prof_braino.... Yeah, you can have servos working on separate power supplies.. In fact, my old robot had two power sources. One for the microcontroller/peripherals and another for the actual motors. If i attached everything to only one power source, the microcontroller would shut off every time the motors came under a heavy load. I would probably put a small filter across the servo. Just to be over cautious

ratronic

DutchBot - I have two servos with pings mounted on my stingray and they work fine from the servo headers on the msr1. Heres a video of it in action and the program I'm using to do simple obstacle detection. http://www.youtube.com/user/1ratronic?feature=mhum#p/u/5/SlGdk_FWJiU