Raspberry Pi Forums

Hi,

So here's the situation: I just received a Raspberry Pi B+ and I was playing around with it earlier today. While I was testing the GPIO stuff, I noticed that something didn't work. I tested my dells, my wires, my breadboard and everything else until I noticed that the ground pin I was using was broken. I tested it with a multimeter. Weird stuff. When I test from the 3V3 to the broken ground, the voltage is about 0.3V. When I try using the 5V to the broken ground, I get about 1.3V.

Is there any way I can fix this? Has this been a problem to anyone else? Is there a maximum voltage that the ground can get? Is there any dangers if I don't place resistances properly in my circuit?

Thanks for your help,

(Sorry if I'm a noob, everyone got to start somewhere )

YES, shorting a GPIO pin to ground without a proper resistor, to limit the currency to the max allowed value of GPIO pin, can overload and break GPIO or even more - your RPi.
it depending to the GPIO pin mode in that the pin was at the time you shortcutted the pin (H, L, X)

(but maybe the "not-working" GPIO pins are only in mode X)

From the readings you are getting you are measuring the wrong pins!

If you get around 1.5v between any two pins you are measuring between 5V and a pin at 3.3V. To get close to 0V you are measuring between two pins at the same level (near enough).

Either that or your meter has a flat battery/is broken. Test your meter with a known good source like a new 1.5V battery.

How are you measuring the voltages on the pins. Directly on the Pi, or via something connected with a cable? Is the cable connected the right way round at both ends?

Have you checked the pin numbering? Pin 2 (5V) is the pin nearest the corner of the board. Pin 6 (0V) is the third pin along the edge.

I think @rpdom's answer is the most likely explanation. There are 8 Ground connections on the J8 header - you must have done something really bad to have broken them all!

Check again with a diagram like this - http://www.raspberrypi-spy.co.uk/2014/0 ... nd-pinout/

The low numbers of the header are at the same edge of the RPi B+ boards as the microSD card slot, most distant from the USB connectors.

How do the other GND pins pan out?, does your circuit work with them?, what meter readings do you get? for the suspect pin what do you measure to the GND test point?

It may be a manufacture defect.

Thanks everyone for your answers, I don't know why, but I let the RPi cool down a little and an hour later, everything was working fine. I can now proceed to blink lights

Thanks again

Vorane wrote:Thanks everyone for your answers, I don't know why, but I let the RPi cool down a little and an hour later, everything was working fine. I can now proceed to blink lights

Thanks again

You shorted something out in your initial testing and caused the polyfuse to overheat. be careful not to short out (directly connect without intervening components) your GPIO pins in the future. I think you've had a lucky escape, often direct shorts will damage components.