some trouble with GPIO

Philip Fischer

Hello,
I have some troubles with the gpio´s. Especially while reading Inputs.

I don´t get a save signal on the Inputs. I do have an external I/O-Board with Pull-down Resistor (also tried PULL-up).
While reading the Inputs, I get some signals for milliseconds although there is nothing connected to the I/O-Board.

Especially when the CPU is more occupied there are a lot more wrong signals. For me it seems like the Inputs of the UP-Board are not stable.

Does anybody else have these problems?

Please help me with this issue.

Thanks
Philip

Nicola Lunghi

Hi Philip
please describe better your setup/post a schematic/photo of it.

Regards
Nicola Lunghi

Philip Fischer

Hi Nicola,

there is Windows 10 Enterprise installed.
I used the 3.3V Power of Pin1 to run the external I/O-Board and also GND of PIN6.
I´m using GPIO 4/17/27/22/6/13/19/26 declared as Inputs as see in the schematic.

I used the same I/O-Board on a Ra-Pi and there was everthing fine.


My first thought were about some currents on the UP- curcuit board. Is there a possibilty of that or maybe the driver vor the GPIO-Pinout?

Thanks
Philip

Nicola Lunghi

Hi
can you do a quick check to see if using PULL-UP instead of pull-down resistor you have issue?
Also double check that you have proper capacitor on the ground/power supply lines of your board.
Another thing: the Up board is not running Linux?
Regards
Nicola Lunghi

Nicola Lunghi

Also a stronger pull up/down could help (3.3k?1K?)

Philip Fischer

Hi,
I tried the same with pull-up resistors. Then the unstable signal is just turned around.
So always when there is a zero-signal on Input I get some peaks on the input.

There is Windows 10 running on the UP-Board.
I will check that with the capacitor later on .