[SOLVED] Problems with GPIO

Hardware related problems and workarounds

[SOLVED] Problems with GPIO

Postby daniel_dbb » Thu Aug 18, 2016 10:36 am

Hi,

I am working arround to get github sample parallella-utils/gpio_dir working. I don't get Output Signal at Gpio pin as it should be (by the book).
I did the same test fro, comandline -> and it does not work as well.

echo "54" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio54/direction
echo "1" > /sys/class/gpio/gpio54/value

Result should be 1 at gpio port 0.
Yes I got 1, but for 4us only.
If I would like to get a control over the signal length. Although reading from /sys/class/gpio/gpio54/value returns 1 but the output level; at gpio port 0 is 0.
Same problem with other ports and at other Parallella boards as well.

Is there a way to check or correct signal OEN and DIRM at Zinq 7000? (see. Figure 14-2 GPIO Channel in ug585-Zinq-7000-TRM.pdf, pagev 384
Is there any other option to programm Gpio?
Is there a Kernel patch dealing with this problem?

Hope to get some help!

Kind regards,
Daniel

Parallella_gpio.png
Logic Analyzer snapshot of Output Signal 1
Parallella_gpio.png (26.14 KiB) Viewed 2007 times
Parallella_gpio.png
Logic Analyzer snapshot of Output Signal 1
Parallella_gpio.png (26.14 KiB) Viewed 2007 times
Attachments
Parallella_gpio1.png
Logic Analyzer snapshot of Output Signal 2
Parallella_gpio1.png (19.84 KiB) Viewed 2007 times
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Re: Problems with GPIO

Postby aolofsson » Sun Dec 18, 2016 9:28 pm

Try this example:
(getting the right GPIO pin offset is the key).

https://github.com/parallella/parallell ... linux_gpio
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