My "MINIRAY" Rov.

[bigbadbob]

No bang but lots of smoke.
I could see it through the plexiglass window on the back of the rov.
So I've got the rov ballasted to float up and drive down so it's usable.
I also got to thinking it would be handy to upload arduino sketches without opening the rov.
I can do it over the rs485 lines but need to trigger a hard reset of the Atmega chip,
I've tried various software methods including watchdog timer triggered by a serial command and using a digital pin to pull reset low but they don't do a full hard reset, the low pulse is not long enough.
resetFunc() is also a soft reset so no use either.
So I'm thinking of using an rf keyfob to trigger it.

[Oddmar]

Or put a reed switch just inside the hull tied to the reset button, and place a magnet near it outside to reset the Arduino.

[asesorplaza1]

Buenos días.

Siento mucho lo de su BEC, espero que los daños solo hayan sido esos, y no haya sufrido daños ningún componente más.

Supongo que usted sabrá mejor que nadie, por qué ha ocurrido eso, pero yo creo que ha sido por un sobrecalentamiento, debido a que el motor le pedía mas potencia al BEC, y durante más tiempo, del que este le puede suministrar.

Yo pondría un BEC de más potencia / amperaje, siempre es mejor que el BEC, trabaje por debajo de sus posibilidades, ante la demanda del motor.

Un saludo.



Good morning.

I'm so sorry about your BEC, I hope the damage was just those, and no more components have been damaged.

I suppose you will know better than anyone, why that has happened, but I think it was because of overheating, because the engine asked the BEC for more power, and for longer, than it can supply it.

I would put a BEC of more power / amperage, it is always better than the BEC, work below its possibilities, faced with engine demand.

Greetings.

[bigbadbob]

Hi AP1, It was a dry joint came loose and shorted a wire to the fets.
My motor only draws a few amps and the ESC has a thermal shutdown so I should be safe there.
Anyway, my new ESC arrived today. I flashed in the updated firmware, set the same settings as last one and....
It refused to arm.
It turned out to be a capacitor between the ppm input and ground that was too high a value, so the pulse was getting elongated.
I love my oscilloscope, i'd never have solved that problem without it.
I pinched the capacitor (tiny surface mound barsteward) off the burned out board and all was well.
Unfortunately using BLHeli mulit firmware in bi-directional mode doesn't allow calibration so you have to do it manually by tweaking firmware settings and Arduino code values.
Test dive tomorrow but it works on the bench.

[bigbadbob]

Or put a reed switch just inside the hull tied to the reset button, and place a magnet near it outside to reset the Arduino.

good idea Oddmar. I have a reed switch in my junk box.

[bigbadbob]

MiniRay swimming happily in his tank.
Holding depth and heading nicely.
H's desperate to swim free in the ocean now, the tank is no life for a wild ROV.

[asesorplaza1]

Buenos días.

Se nota que tu ROV también esta cansado del confinamiento y esta deseando salir a explorar en mar abierto.

Un saludo.


Good morning.

You can tell your ROV is also tired of confinement and is looking forward to exploring in the open sea.

Greetings.

[bigbadbob]

he keeps sending me symbols on the video screen...

[bigbadbob]

yesterday I added a ring of led's around my camera.
I'm not convinced of the benefits of lights on such a small ROV as they are likely to cause back-scatter off the sediment in the water but for night dives and for illuminating dark spaces they might be handy.
I did not want to add them outside the hull as I would need to drill more holes in the hull for very little benefit.
So adding a ring of them around the camera with a hood to prevent reflections off the inside of the dome seemed a good compromise.
interestingly, the light will hit the dome at an angle and be refracted away from the camera as the acrylic is more dense than the air (actually nitrogen) in the hull. when the light passes through the acrylic into the water it will be refracted again slightly back towards the plane of the camera lens but not parallel with it so will hopefully provide a more diffuse light and less back-scatter straight down the lens. That's the theory.... we'll see how it works in practice.



The leds are driven from a PWM output of the arduiono (pin D3) via an opto-isolator so they draw their power from the propulsion supply, and the brightness is controlled by buttons on the ps2 controller.

I also added a reed switch inside the hull that allows me to reset the arduino from outside with a magnet and therefore upload sketches over the rs485 lines without opening the hull. I'm just waiting on a usb to rs485 converter arriving so I can test that.

[bigbadbob]

Well Oddmar. your reed switch suggestion works great.
My usb to RS485 converter arrived today and I made a short programming tether cable for my ROV.
A 12v SLA powers the electronics and the usb-RS485 takes care of the data.
I hold a magnet to the reed switch while the Arduini IDE is compiling the sketch and as soon as it says "uploading" I remove the magnet.
all works well.