Beaglebone brick after lasers added


#1

Hi OpenROV members,

We are in the process of assembling our OpenROV. Everythings is finished and works well except the lasers. The last time we tried to add them, it bricked the beaglebone (no more users lights).

We bought a new beaglebone but before I do another test with the lasers, I would like to know if you have already encountered such problems ?

Thanks for your help

Arnaud


#2

It would probably be a good idea to test the Laser LED's on their own with a power source first to make sure they are not shorted. I don't have any of these yet to test so I am not sure what voltage they operate at, be it 3,3V or 5V I suspect they are 5V so you could try a 1K resistor in series with the LED & +5V. The 1K resistor will limit the current to 5ma which should be enough to turn on the LED.

+5V------1K----------|>|----------gnd

Resistor led


#3

I have the lasers running. They work off 5 volts on the 2.5 board which they plug into. On the 2.5 board there is a jumper to set the voltage and it comes set to 5 volts. If you were trying to run them on the original cape board they would be getting 12 volts which is to high. I don't see how this would kill the beaglebone as they don't connect to it directly. See attached for lasers working, it is a little hard to see.

David has a good idea to test them first with a power supply. I did this just to play with them.

good luck

John

1004-openrovlaserslightsv1.jpg (350 KB) 1005-openrovlaserslightsv2.jpg (227 KB)

#4

John you have created a Monster :) looks like you are getting lots of use with it. I got my thrusters 3D printed and they are in the mail so I should have them soon. Did you treat yours to make them waterproof? I was thinking of using an acetone vapour.


#5

I did not do anything. I am on my 3rd revision for the the thruster housings. When I have it in the water you see bubbles coming out of the housing. The first 2 sets I printed on an FDM3000 and the last set I printed on a MakerBot. The MakerBot is much faster. It is hard to see but I have the new IMU/Depth module screwed to the top of my metal frame. In the picture it is in the upper right corner. I really want to put mine in the lake again but it has been cold and we have snow. Running a laptop in the cold and getting your hands wet is tough in winter.


#6

Guys,

Thank you for your advices.

We've finally put the lasers on the ROV and everything works fine :)

Time for holidays now !

Arnaud


#7

What is the purpose of the lasers?


#8

You need them to be able to measure what you see underwater.

A.


#9

The lasers are mounted so that the beams are 10 cm apart and parallel to one another. So if you point the lasers at an underwater object, the two red spots on the object will be 10 cm apart, and from that you can determine the size of the object.

-W