Hooking up Servo = Fried Pi

#1

Hi all-

I finally got the code working to upload to the cape from the Raspberry Pi! However...

In order to test that the communication was working, I plugged in the simplest test setup handy - the servo. The second the pins made contact, I heard the servo twitch and then lost power to the Pi. I quickly unplugged, but to no avail. Even when disconnected from the cape and powered by the onboard USB mini, I don't even get a power LED.

I am not really sure why this may have happened. The Pi is essentially wired just like a BeagleBone would be, getting 5v from the same pin. My only thought is that somehow the servo may have been wired wrong...? I connected it according to the wiki:.Any ideas? Could the connector in the picture simply be upside down?

#2

i've used this picture for reference alot of times. this is correct.

i dont have a specific answer to why your Pi board fried. but one should never connect electronics together with power applied. i'm thinking some kind of surge could have caused this.(the servo uses alot of power at startup to go to center position)

#3

Hmm that sounds plausible. I am going to try monitoring voltage on the pins while connecting the servo to see if a spike happens. A new Pi is in the mail, but I don't want to plug it in unless I know it's safe.

#4

Could it be that you didn't follow this picture?

#5

I did not follow this picture. I was under the impression this was only necesarry when powering the ESCs (which I didn't even have connected). A new Pi arrives by mail Friday, but in the meantime I plan to do some voltage measurements on the pins to see if there is any spike when the servo is plugged in.

#6

Did you plug the servo in while the rest of it was powered on? That might've been the problem. Also, having one ESC plugged in to provide the power to the servo (with that jumper off) might solve the issue, since the ESC will provide power to the bus, as noted in that section of the assembly guide.

#7

Yes, in my stupidity I did just plug it in with everything running. I also did not read the whole guide until after the fact, just skipped down to the picture.

#8

I would've done the same thing. Luckily, the rasperry pi is $40 instead of $80 like the beaglebone!

#9

Its correct than you can leave the jumper on if you just have a servo and not a esc connected. with esc connected, you have to remove it.