On 23/01/18 18:53, Dennis Lee Bieber wrote:
> On Tue, 23 Jan 2018 16:43:21 +0000, RobH  declaimed the
> following:
>
>
>> All of the above commands return 0
>>
>> I set the direction to IN then did gpio readall which shows the gpio17
>> pin as IN and 0 voltage.
>>
>> Then I connected the positive jumper wire to the 3.3 volt pin, and then
>> measured th voltage across the positive and ground wires, which was 3.28
>> Volts.
>
>  If the sequence (below) always reports 0, then it would be safe to
> presume that the GPIO circuitry is blown (or there is confusion as to which
> pin is really being tested). I'm using the -1 option to specify the
> physical header pin
>
> gpio -1 mode 11 in
> #header 11 jumpered to GND (header pin 9, as I recall, is a ground)
> gpio -1 read 11
> #should be 0
> #now jumper header 11 to 3.3V (header pin 1 or header pin 17)
> gpio -1 read 11
> #should be 1 -- if it is still 0, dead GPIO circuit
>
> #with nothing connected to header pin 11
> gpio -1 mode 11 out
> gpio -1 write 11 0
> gpio -1 read 11
> #should be 0
> gpio -1 write 11 1
> gpio -1 read 11
> #should be 1, if this is 0 a REALLY dead GPIO, as the internal latches
> can't hold an output value.
>

When I do

pi@raspberrypi:~ $ gpio -1 mode 11 in
pi@raspberrypi:~ $ gpio -1 read 11
0
pi@raspberrypi:~ $ gpio -1 read 11 Jumper header to 3.3v
0
gpio -1 read 11
0

Now nothing connected to the gpio pins

pi@raspberrypi:~ $ gpio -1 mode 11 out
pi@raspberrypi:~ $ gpio -1 write 11 0
pi@raspberrypi:~ $ gpio read 11
1

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