C GPIO
#10
(08-25-2016, 11:17 AM)MarkHaysHarris777 Wrote:
(08-25-2016, 08:24 AM)martind1983 Wrote: Hi Mark.

First off, thank you for comprehensive help.

Thus, as I got your point. I do not have to modify device tree because of pins connected to some peripheral, just to stop and unload driver should be enough. However, this is not completely through for every peripheral. Thus, for some of them I also have to modify device tree and un-connect so pins (I want to use) and which are also dedicated to peripherals.

For example: I cannot find that UART peripheral driver to which PB0, PB1 would be loaded in the kernel. Does it mean, that I also have to modify dts/dtb to un-connect these two pins from UART2 in device tree?

Is such a rule valid for all GPIOs connected to peripheral which information about is enumerated in DTS?

Thank you.                                     Martin Smile

One more question. All the pins led out on the board and which are also dedicated to some peripherals I have to first turn off special functionality before using them as normal GPIO?

No, not necessarily.

... as long as the pins (channels) are not actually being used 'now' you can use them for what-ever you want. But, that's a big if.  If a driver is running that uses the channel, you will need to stop and unload the driver... but, you don't necessarily have to edit the dtb|dts in order to do this.

That said, it is best to use GPIO pins that are 'free' first.  On the diagram , the green and then maybe the blue. The main exception right now is the pin(7) GPIO04 which is s-pwm and used for the LCD backlight... because it is on a pwm channel even though you can turn it on and off (if you have the correct base address, or use sysfs) it still doesn't work right, because it is 'very' dim ... and, it has a pwm signal on it.  In this case you must not only edit the dtb|dts, but also unassociate the pin, and you need to stop the driver and unload it (a lot of work, just use another GPIO pin).
  Reply


Messages In This Thread
C GPIO - by igna09 - 06-10-2016, 12:41 PM
RE: C GPIO - by martinayotte - 06-10-2016, 01:52 PM
RE: C GPIO - by igna09 - 06-10-2016, 02:16 PM
RE: C GPIO - by martinayotte - 06-10-2016, 03:10 PM
RE: C GPIO - by martind1983 - 08-24-2016, 09:55 AM
RE: C GPIO - by igna09 - 06-11-2016, 02:51 AM
RE: C GPIO - by martinayotte - 08-25-2016, 07:35 AM
RE: C GPIO - by martind1983 - 08-25-2016, 08:24 AM
RE: C GPIO - by MarkHaysHarris777 - 08-25-2016, 11:17 AM
RE: C GPIO - by martind1983 - 08-29-2016, 01:30 AM
RE: C GPIO - by martind1983 - 08-29-2016, 03:50 AM
RE: C GPIO - by MarkHaysHarris777 - 08-29-2016, 05:25 AM
RE: C GPIO - by martind1983 - 08-31-2016, 03:47 AM
RE: C GPIO - by pfeerick - 08-31-2016, 04:14 AM
RE: C GPIO - by martind1983 - 08-31-2016, 04:36 AM
RE: C GPIO - by MarkHaysHarris777 - 08-29-2016, 05:04 PM
RE: C GPIO - by MarkHaysHarris777 - 08-31-2016, 04:09 AM
RE: C GPIO - by KnReLe - 08-31-2016, 07:27 AM
RE: C GPIO - by martind1983 - 09-01-2016, 05:08 AM
RE: C GPIO - by MarkHaysHarris777 - 09-01-2016, 05:29 AM
RE: C GPIO - by martind1983 - 09-01-2016, 08:04 AM
RE: C GPIO - by KnReLe - 09-01-2016, 08:52 AM
RE: C GPIO - by martind1983 - 09-01-2016, 09:06 AM

Possibly Related Threads…
Thread Author Replies Views Last Post
  RPi.GPIO python module for Pine A64/A64+ aquilegia 98 129,877 12-15-2022, 08:40 PM
Last Post: Fadazo
  fm transmitter with gpio weasel18 2 4,755 09-10-2019, 04:28 AM
Last Post: desai_amogh
  How to use dts or other setup to declare gpio pin Interrupt (e.g. a button)? dkebler 1 3,549 06-12-2019, 10:37 AM
Last Post: dkebler
Lightbulb Sample GPIO codes highlighting RPi.GPIO-PineA64 and the PI bus MarkHaysHarris777 6 10,961 06-07-2019, 12:37 AM
Last Post: tllim
Star GPIO, SPI and I2C C++ Lib databit 7 11,048 02-04-2019, 05:45 AM
Last Post: Jeff R
Information Howto: Controlling Pine64 GPIO via the filesystem (sysfs) on linux pfeerick 4 11,758 01-24-2019, 03:36 AM
Last Post: Fifth
  GPIO and SPI SamR1 20 31,184 03-15-2018, 10:32 AM
Last Post: jomoengineer
Question GPIO shockr 7 14,595 03-11-2018, 01:52 AM
Last Post: jomoengineer
  Read GPIO problem shworker 14 20,946 08-17-2017, 01:21 PM
Last Post: martinayotte
  GPIO fiq capability joseph 3 6,012 11-10-2016, 06:07 PM
Last Post: joseph

Forum Jump:


Users browsing this thread: 1 Guest(s)