I/O Pins Receive Unstable Power When Motors Are Running

userHead scottjp8.9.02 2016-06-06 03:01:44 5161 Views6 Replies
Recently, I have been building a robot using an old romeo v1.1, a 9g servo, and a parallax Ping))) sensor ( I ran into a problem when I tried to run the ultrasonic sensor and servo while the motors were running. The servo twitched rapidly and the ping sensor produced inaccurate readings. However, with the motors off, the servo and sensor worked perfectly. I tried using external servo power however the problem remained. Would some capacitors fix this problem? If so, what size?
2016-06-20 19:05:22 Hi scottjp8.9.02,

Very good to know that, we will update it to wiki later.

Thanks for following up! :)
userHeadPic Leff
2016-06-17 08:18:37 Adding the capacitors on each motor fixed the problem. Thank you for all the help! userHeadPic scottjp8.9.02
2016-06-13 18:19:17 Hi Scott,

This is the kit including motor, servo, ultrasonic sensor, very similar to your project. ... ebug_Motor

I asked my colleague about your problem, and they suggested to add a 0.1uF capacitor between each motor's positive and negative pole.

Please try to see if it works.
userHeadPic Leff
2016-06-13 07:46:20 Without the external servo power supply, the servo jitters and will not move properly. userHeadPic scottjp8.9.02
2016-06-11 09:48:32 I am using a chassis similar to the DFrobot 4wd mobile platform ( ... tform.html). A 9v battery pack powers the Romeo through the barrel jack connector. A battery pack with 4 AA batteries powers the motors only. Another 4 AA battery pack is connected to the external servo screw terminal. Both the servo and ping sensor are connected to digital pins that are not used for motor control. userHeadPic scottjp8.9.02
2016-06-08 15:54:39 We have several kits that using Romeo, servo, motor and ultrasonic sensor. e.g. ... ption=true no need to use a capacitor.

May I have a look at your project, mainly about the power source, and how do you supply power to Romeo V1?
userHeadPic Leff