On 13/06/18 20:19, Dennis Lee Bieber wrote:
> On Wed, 13 Jun 2018 19:41:02 +0100, druck  declaimed the
> following:
>
>> 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.
>>
>
>  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".
>
>> Ground to 5V should give 5V
>> Ground to GPIO set high should give 3.3V
>
>  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.
>
>> 5V to GPIO should give 0V because they aren't connected.
>
>  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.
> .
>>
>> ---druck
>
>

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.

Again as I posted earlier, it was the crappy £5 ebay camera which was
the fault/problem and not the sensor at all.

--- SoupGate-Win32 v1.05