# No data received from sensor

• posted
mm0fmf,
Yes, really.
I think your logic chip has broken. Did you put 5v on 3.3v inputs perhaps ? :-)
Regards, Rudy Wieser
• posted
Martin,
In which case the voltage meter would pull the pin to whatever voltage is on the other side of it (ignoring clamping and so on), again resulting in a 0v difference.
In that case current will flow, and as voltage meters nowerdays are rather high-impedance, it would show (nearly) 5v instead of Zero.
Not sure what would happen when, with "active" pull-down/-up resistors, that current becomes too low though.
That is the *only* measurement here which actually means anything.
And measuring that voltage (or not) would be relevant because ?...
Remember that the Pi won't run/would reset if that voltage is too far off. (besides showing a yellow lighting icon on the screen if its just a bit off).
Regards, Rudy Wieser
• posted
Ok I have received the new infra red wide angle camera, connected it up and got the PiZero fired up, did this: raspistill -k, and the camera took my picture.
was at fault, and not the sensor as it works fine now.
• posted
no it means the voltage difference between the 2 leads is 0. in other words they are both the same voltage now back to the original statement, measuring between a GIPO & 5v reads 0v, so they are both the same voltage.
```--
Logic doesn't apply to the real world.
-- Marvin Minsky```
• posted
Alister,
And as the OP (correctly) stated, they are (thus) both at 5v.
And if his measurement is correct (and it is), and he reads 0v difference, than, as Mark has got the same result on his voltage meter, his leads should logically be at 5v too (even though they are not touching anything but air).
In other words, your reply doesn't *explain* why the OP would be right, and Mark wouldn't be.
Hint: voltage reference.
Regards, Rudy Wieser
• posted
I think you will find i did I stated that there was no voltage difference between the 2 leads. they would not both be at 5V as Voltage is a difference between points so this is an invalid measurement.
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• posted
Alister,
And I did not disagree with that in any way.
The OP had at least one lead directly touching the 5v pin, so that lead *is* at 5v. As there was a zero voltage difference indicated, logically that other lead should be at 5v too. Or do you want to claim that either of those conclusions (one for each lead) is incorrect (and if so, how/why) ?
Although you're in the right neighbourhood, you're still not doing a good job at *explaining* to why marks (and/or the OPs too?) reasoning is wrong. Do you think a novice would know what you ment there ?
Mind you, I'm doing some well-ment prodding here. The hardest part of "just knowing you're right" is to explain it to yourself, and after it to others. Mark no doubt knew that, and made good use of it. :-)
Regards, Rudy Wieser
• posted
Sure and given that one of them is known to be at 5V relative to ground the other one is also at 5V relative to ground - at least as long as the voltmeter is connected.
Now please stop with the pedandtry and assume a 'relative to ground' where needed.
```--
Steve O'Hara-Smith                          |   Directable Mirror Arrays
C:\>WIN                                     | A better way to focus the sun ```
• posted
No!
No!
No!
If you measure between 2 pins and get 0V it /could/ mean they are at the same potential, or it could mean there is *NO* connection between them. That's why you always measure from the common ground to the pin.
Ground to 5V should give 5V Ground to GPIO set high should give 3.3V 5V to GPIO should give 0V because they aren't connected.
---druck
• posted
Correct.
Correct
Correct
Almost there...
but not quite.
• posted
On Wed, 13 Jun 2018 19:41:02 +0100, druck declaimed the following:
We presume the board is not broken -- thereby all pins do have a shared common ground level, and a voltmeter connected between any two pins should report the potential (voltage) difference between those two pins, doesn't matter what the voltage relative to ground is. Basically, which ever pin has the voltmeter /black/ (using standard convention for voltmeters) /defines/ "ground level", and the /red/ lead will report the potential difference from "ground level".
Note: unless I misunderstood the situation gravely, the GPIO is being used as an INPUT and it is the motion sensor/detector that is setting the pin value. That sensor is powered by the 5V system, which is why we have the concern that if it is putting 5V on the GPIO, it could be causing damage to the pin circuits.
But they are connected -- by the RPi common ground. If groundGPIO can be measured and ground5V can be measured, and both are not 0V, then the differential between 5VGPIO can also be measured directly -- one pin becomes the effective "ground" and the other will present a voltage relative to the other.
Yes, if groundGPIO shows 0V it could mean the pin is really at ground level (and the differential between it and 5V is still valid), or the pin is physically isolated from the rest of the circuit in which case it will never register any non-0V and you might as well toss that pin into the trash. .
```--
Wulfraed                 Dennis Lee Bieber         AF6VN
wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/```
• posted
I don't think anybody knows whether the RPi is still intact and undamaged. If the OP showed some sensible measurements we might know if its still healthy.
```--
Martin    | martin at
Gregorie  | gregorie dot org```
• posted
Gentleman, please! I never thought that my initial post would cause so much ruckus as you Yanks say.
I post the link for the tutorial I followed and hoped that some of you would have viewed it to clear up any anomalys I may have made with my initial post.
the fault/problem and not the sensor at all.
• posted
Ding! Ding! Ding! Ding! We have a winner!
• posted
e
There IS a connection between them. The voltmeter may (should) have a high resistance but not an infinite one. So any open pin will be pulled to the level of a live one. A non-open pin may well (and should) be able to source or sink the very small current throught the voltmeter and still impose its own potential.
The measurement as stated is valid and sensible.
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/ \  Mail | -- No unannounced, large, binary attachments, please! --```
• posted
Oh dear.
```--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.```
• posted
Finally someone who actually understands electricity!
```--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.```
• posted
Druck,
Yes!
Yes!
And that one is what marks joke is about, and I asked you guys to counter. Just saying "no" doesn't cut it in the slightest I'm afraid.
So your explanation is that the voltage meter is broken ?
Now its my place to utter a "no!" :-)
Regards, Rudy Wieser
• posted
Rob,
Don't worry about that, it was not your doing. While mark triggered it with his joke, the following "ruckus" is all my doing (my apologies if that bothered you).
But jeez, what a simple "can you explain how that reasoning is faulty ?" can result in ...
Regards, Rudy Wieser
• posted
mm0fmf,
Wrong, as they *are* connected.
Think about why you call one pin/location "5v" and another "0v" (hint: as opposed to ... what exactly ?).
Regards, Rudy Wieser

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