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Topic: Blown arduino board - grounding problem with h bridge (Read 92 times) previous topic - next topic

robster278

May 05, 2019, 10:17 pm Last Edit: May 05, 2019, 10:19 pm by robster278
This was my first arduino project and my first time posting on the forums. I appreciate the opportunity to tap the knowledge of the community here.

I've just blown my arduino rev2 wifi (it overheated massively for a while, the on LED flickered for about a minute then the whole board just permanently died).

I've gone back through my workings and I can see one error I made but I don't know whether it would have been serious enough to overheat and blow the board.

I bought a Pololu md30a h bridge to control a 12v motorised ball valve. (The Arduino itself was powered by a separate 9v power supply). As per the diagram here https://a.pololu-files.com/picture/0J6505.1200.jpg I was meant to ground the left side of the h bridge to the arduino as well - the bottom left connection in the diagram. I did not do this, I only fed the PWM and direction connections on the h bridge to 2 output pins on the arduino. Everything on the right side of the h bridge in the diagram I did correctly. Would this lack of grounding to the arduino have been enough to overheat the board and blow it? I also had a water flow sensor drawing 15ma at 5v from the 5v pin on the arduino and every 3 seconds the arduino was sending POST data to a webpage through its wifi module all at the same time as I was sending output through the 2 pins to the h bridge to control the valve.

Thanks



robster278

Or if i can pose a much more simple question:

What are the dangers if you do not ground a pwm output from an arduino to the component you are sending the pwm signal to?

ballscrewbob

Normally an item would not work or would tend to be erratic without the ground.

Dont personally know of a way to blow something that does not have that ground.

Bob.
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

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