kirby2ig
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Raspberry pi warranty

Mon Dec 31, 2012 1:19 pm

The GPIO pins are not working on my pi. I was wondering if I could get it exchanged for a new one and if so, how would I do it?

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alexeames
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Re: Raspberry pi warranty

Mon Dec 31, 2012 1:31 pm

Best to ask the supplier how to return it. What makes you sure the GPIO pins aren't working though?

Which pins are you trying to use?
What are you trying to do with them?
What does your circuit look like?
What code are you using to drive it?

The number of failed Pis is so lo, there's got to be a chance (even a small one) that it's operator error.
Alex Eames RasPi.TV, RasP.iO

kirby2ig
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Re: Raspberry pi warranty

Mon Dec 31, 2012 1:35 pm

pin 1 gives me 1.7v instead of 3.3v, so that pretty much makes the GPIO unusable.

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mahjongg
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Re: Raspberry pi warranty

Mon Dec 31, 2012 1:47 pm

could still be that you only programmed it to be a weak pullup to 3V3.
I've seen complaints like this before that were simply software errors.

khulat
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Re: Raspberry pi warranty

Mon Dec 31, 2012 1:57 pm

Well if he is talking about the 3v3 Power Pin I don't think it could be a software error.

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Re: Raspberry pi warranty

Mon Dec 31, 2012 2:22 pm

khulat wrote:Well if he is talking about the 3v3 Power Pin I don't think it could be a software error.
If that pin is reading as 1V7 then either
  • nothing is working on your Pi
  • You are measuring it wrong
To measure volatges on the GPIO pins they must measured relative to GND or 0V
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

kirby2ig
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Re: Raspberry pi warranty

Mon Dec 31, 2012 2:44 pm

Also, when I try to receive inputs, the pi will say that sometimes the pin is high with nothing connected to it. I have to use a different ground because when I use pin 6 as ground, pin 1 gives me 0.78v, but my multi-meter works because TP1 and TP2 give me a perfect 5v, along with pin 2

Ravenous
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Re: Raspberry pi warranty

Mon Dec 31, 2012 2:48 pm

Do you have a circuit, or maybe a picture, of exactly what you have connected to the pi when you do all these tests?

It's possible the pi is OK but just the GPIO pins have a problem, but that's very unlikely...

kirby2ig
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Re: Raspberry pi warranty

Mon Dec 31, 2012 2:49 pm

Also, when I measure the voltage of some GPIO pins, the value is 5v even if the pin is low.

kirby2ig
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Re: Raspberry pi warranty

Mon Dec 31, 2012 2:55 pm

At first, I thought that I was just wiring the circuit wrong, so I looked at this tutoriol on the adafruit website only to find that the LED was wired exactly right.

http://learn.adafruit.com/raspberry-pi- ... using-leds

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rpdom
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Re: Raspberry pi warranty

Mon Dec 31, 2012 3:00 pm

kirby2ig wrote:Also, when I try to receive inputs, the pi will say that sometimes the pin is high with nothing connected to it.
Unless you set the pins to use internal pull-up or pull-down resistors, or connect them to external resistors, the pins will float and give random readings of high or low.
I have to use a different ground because when I use pin 6 as ground, pin 1 gives me 0.78v
Well, that sounds a bit odd. Which pin did you use as ground instead?
but my multi-meter works because TP1 and TP2 give me a perfect 5v, along with pin 2
Ok, sounds like your meter is working.

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Re: Raspberry pi warranty

Mon Dec 31, 2012 3:06 pm

I am using ground from an old power supply instead.

kirby2ig
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Re: Raspberry pi warranty

Mon Dec 31, 2012 3:07 pm

I am also using a momentary tact and a 10kohm resistor. The same thing happens.

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alexeames
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Re: Raspberry pi warranty

Mon Dec 31, 2012 3:08 pm

kirby2ig wrote:I am using ground from an old power supply instead.
Is that ground connected to the RPi ground? It should be.
Alex Eames RasPi.TV, RasP.iO

kirby2ig
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Re: Raspberry pi warranty

Mon Dec 31, 2012 3:18 pm

The power supply ground isn't connected to the RPi ground. How would I connect it?

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alexeames
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Re: Raspberry pi warranty

Mon Dec 31, 2012 3:38 pm

You'd probably be better off using a breadboard and using a ground rail on that for all your grounds, originating from one ground pin (pin 6) on the GPIO header.

The trouble is we're firing blind in helping you. A photo or circuit diagram would help a lot.
None of us are above making a silly mistake - I made one myself last night - measuring the Voltage on the wrong side of a resistor. It cost me quite a lot of lost time wondering why the circuit didn't work as it should. :lol:

You can also try pin 9, pin 14, pin 20 and pin 25 as grounds.
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techpaul
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Re: Raspberry pi warranty

Mon Dec 31, 2012 4:04 pm

Step 1 Disconnect everything from GPIO connector

Step 2 Measure TP1 to TP2 voltage check 5V

Step 3 Measure pin 1 of GPIO relative to gnd ( TP2 or GPIO pin 25 are probably easiest points ) this should be 3V3.

Step 4 Meaure pin 2 of GPIO relative to gnd ( TP2 or GPIO pin 25 are probably easiest points ) this should be 5V.

This will prove that the GPIO pins are likely to be correct. If you add a circuit and these change there is a problem in your circuit

If you need to add a circuit with another power supply make sure its OUTPUT negative, or 0V or GND is connected to GND of GPIO connector (9, 25, 6, 14, 20), often it is better to connect at LEAST one of these pins to your circuit.
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

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Re: Raspberry pi warranty

Mon Dec 31, 2012 4:23 pm

kirby2ig wrote:The power supply ground isn't connected to the RPi ground. How would I connect it?
I think you may be looking at things from a wrong perspective.

I'm going to assume you know nothing, not because I think you don't personally, but for the sake of anyone else coming here

So, electric current goes in circles. It starts at the positive end of the power supply, goes through the circuit, and back to the negative end (and the power supply shoves it back up to the positive end)
If there's a break so it can't get back, it won't set off.

Your meter can be part of a circuit. Put the black lead on the negative end of the power supply, be it TP2 or the metal of the USB socket or P1-06, and the red lead on the positive end of the power supply such as P1-02, and current will flow and your meter will display it.
Put the black lead on some random unconnected bit of metal, be it another PSU labeled "GND" and there's no way for the current to get back, so it won't flow.

Just because that other PSU has a pin labelled GND or earth or chassis doesn't mean it's connected to the earth in your flowerbed.
The same goes for ground on the Pi.
It's called ground because that's where Marconi connected it. He stuck a big metal plate into the ground. But ground on the Pi isn't ground. In fact the whole power supply is isolated.

So to measure a voltage on a random P1 pin you must complete the circuit with your meter, using the negative rail of the Pi

georgekok97
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Re: Raspberry pi warranty

Mon Dec 31, 2012 5:05 pm

which psu do you have exactly ...?

kirby2ig
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Re: Raspberry pi warranty

Mon Dec 31, 2012 5:28 pm

I found the problem. The adafruit GPIO cable was manufactured backwards. I am going to need to order a new one because it will not fit in my case anymore with the cable backwards.

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alexeames
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Re: Raspberry pi warranty

Mon Dec 31, 2012 6:45 pm

kirby2ig wrote:I found the problem. The adafruit GPIO cable was manufactured backwards. I am going to need to order a new one because it will not fit in my case anymore with the cable backwards.
How about removing the case just to get the circuit finished? If you're following an adafruit tutorial, why don't you tell us which one and what you're using? It's very hard to help people without knowing what they're doing. :lol:
Alex Eames RasPi.TV, RasP.iO

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Re: Raspberry pi warranty

Mon Dec 31, 2012 10:31 pm

I don't need help anymore. I bought the adafruit raspberry pi kit and the pre-assembled pi cobbler was put together backwards. All of my circuits work now.

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alexeames
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Re: Raspberry pi warranty

Mon Dec 31, 2012 10:53 pm

kirby2ig wrote:I don't need help anymore.
Famous last words :lol:
kirby2ig wrote:I bought the adafruit raspberry pi kit and the pre-assembled pi cobbler was put together backwards. All of my circuits work now.
Great. Happy new year :)
Alex Eames RasPi.TV, RasP.iO

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