At Wed, 30 Jun 2021 23:25:19 -0700 (PDT) beagleboard@googlegroups.com wrote:

> 
> config-pin P9_26 gpio
> ERROR: open() for /sys/devices/platform/ocp/ocp:P9_26_pinmux/state failed, 
> No such file or directory
> 
> 
> write "in" to /sys/class/gpio/gpio14/direction (for input) 
> write "out" to /sys/class/gpio/gpio14/direction (for output) ... Did you 
> mean gpio15 (not gpio14)? gpio15 ... UART1_TXD
> 
> I will try UART4_RXD (P9_11 - gpio30) and UART4_TXD (P9_13 - gpio31).

Why are you speificly going after UART pins?  Are you wanting to actually use 
the UARTs?

> 
> 
> Dátum: streda 30. júna 2021, Ä as: 17:21:06 UTC+2, odosielateľ: 
> hel...@deepsoft.com
> 
> > At Wed, 30 Jun 2021 07:03:38 -0700 (PDT) beagl...@googlegroups.com wrote:
> >
> > > 
> > > I tried to use write operation on /sys/class/gpio/gpio14 (gpio15)/value, 
> > > but nothing happens (from 
> > > https://github.com/RobertPHeller/JAVALinuxGPIO/blob/main/LinuxGPIO.java 
> > )
> > > I figured out that PrintStream doesn't throw exceptions so I tried to 
> > use 
> > > FileOutputStream.
> > > Then I got exception:
> > > 
> > > java.io.IOException: Operation not permitted
> > > at java.io.FileOutputStream.write(Native Method)
> > > at java.io.FileOutputStream.write(FileOutputStream.java:290)
> > > 
> > > Read operation via FileInputStream is ok.
> > > 
> > > I run my java application with "sudo".
> > > 
> > > gpio14 ... P9_24 (UART1_TXD)
> > > gpio15 ... P9_26 (UART1_RXD)
> > > Right?
> >
> > First of all you need to configure the pins:
> >
> > config-pin P9_24 gpio
> > config-pin P9_26 gpio
> > ("config-pin -l P9_24" list the possible options, "config-pin -q P9_24" 
> > displays the current settings. There is an extended versin of config-pin 
> > under /opt/source/bb.org-overlays/tools/beaglebone-universal-io/)
> >
> > You then need to "export" the GPIO pins:
> >
> > write "14" to /sys/class/gpio/export
> > write "15" to /sys/class/gpio/export
> >
> > You also need to configure the direction:
> >
> > write "in" to /sys/class/gpio/gpio14/direction (for input)
> > write "out" to /sys/class/gpio/gpio14/direction (for output)
> >
> > (My GPIO class does that in the constructor)
> >
> > To avoid sudo, you put yourself into the gpio group:
> >
> > sudo usermod -a -G gpio $USER
> >
> > then logout and log back in.
> >
> > > 
> > > 
> > > Dátum: utorok 29. júna 2021, Ä as: 16:42:45 UTC+2, odosielateľ: 
> > Dennis Bieber
> > > 
> > > > On Tue, 29 Jun 2021 07:02:06 -0700 (PDT), in
> > > > gmane.comp.hardware.beagleboard.user Radovan Chovan
> > > > <rado991-re5jqee...@public.gmane.org> wrote:
> > > >
> > > > >Thanks for all your comments.
> > > > >
> > > > >Is there any mapping between /sys/class/gpio and schematic diagram of 
> > > > >Beaglebone Black board?
> > > > >
> > > > Does
> > > > https://vadl.github.io/beagleboneblack/2016/07/29/setting-up-bbb-gpio
> > > > provide any help.
> > > >
> > > > >I want to use pin P9_24 (UART1_TXD) and P9_26 (UART1_RXD).
> > > > >https://beagleboard.org/static/beaglebone/BEAGLEBONE_SCHEM_A3.pdf 
> > (page 
> > > > >11/11)
> > > > >
> > > > P9_24 equates to GPIO15, but in raw pin numbering appears to be 97. As
> > > > I recall, there are 32 GPIOs per "CHIP", so that might be the 4th CHIP
> > > > (counting from 0), and the second GPIO (again, counting from 0)
> > > >
> > > > >>> divmod(97, 32)
> > > > (3, 1)
> > > >
> > > > P9_26 -> GPIO14, raw 96...
> > > >
> > > > >>> divmod(96, 32)
> > > > (3, 0)
> > > > >>> 
> > > >
> > > > HOWEVER, 
> > > > debian@beaglebone:~$ gpioinfo
> > > > gpiochip0 - 32 lines:
> > > > line 0: "MDIO_DATA" unused input active-high
> > > > <SNIP>
> > > > line 12: "UART1_CTSN" "P9_20" input active-high [used]
> > > > line 13: "UART1_RTSN" "P9_19" input active-high [used]
> > > > line 14: "UART1_RXD" "P9_26" input active-high [used]
> > > > line 15: "UART1_TXD" "P9_24" input active-high [used]
> > > > line 16: "GMII1_TXD3" unused input active-high
> > > >
> > > > indicates that it is CHIP0, and the "line" 14/15 map to the GPIOxx (so 
> > for,
> > > > say, GPIO45 it becomes chip 1, line 13)
> > > >
> > > > The gpioinfo command is provided by installing the gpiod package.
> > > >
> > > >
> > > > debian@beaglebone:~$
> > > > /opt/source/bb.org-overlays/tools/beaglebone-universal-io/config-pin -i
> > > > p9_26
> > > > Pin name: P9_26
> > > > Function if no cape loaded: gpio
> > > > Function if cape loaded: default gpio gpio_pu gpio_pd gpio_input uart 
> > can
> > > > i2c pru_uart pruin
> > > > Function information: gpio0_14 default gpio0_14 gpio0_14 gpio0_14 
> > gpio0_14
> > > > uart1_rxd dcan1_tx i2c1_sda pru_uart pru1_in16
> > > > Kernel GPIO id: 14
> > > > PRU GPIO id: 46
> > > > debian@beaglebone:~$
> > > > /opt/source/bb.org-overlays/tools/beaglebone-universal-io/config-pin -i
> > > > p9_24
> > > > Pin name: P9_24
> > > > Function if no cape loaded: gpio
> > > > Function if cape loaded: default gpio gpio_pu gpio_pd gpio_input uart 
> > can
> > > > i2c pru_uart pruin
> > > > Function information: gpio0_15 default gpio0_15 gpio0_15 gpio0_15 
> > gpio0_15
> > > > uart1_txd dcan1_rx i2c1_scl pru_uart pru0_in16
> > > > Kernel GPIO id: 15
> > > > PRU GPIO id: 47
> > > > debian@beaglebone:~$
> > > >
> > > >
> > > > (Unfortunately, that script doesn't tell one what "default" mode IS 
> > for the
> > > > pin, but does have more capability than the compiled config-pin that
> > > > replaces it)
> > > >
> > > >
> > > > -- 
> > > > Dennis L Bieber
> > > >
> > > >
> > > 
> >
> > -- 
> > Robert Heller -- Cell: 413-658-7953 <(413)%20658-7953> GV: 978-633-5364 
> > <(978)%20633-5364>
> > Deepwoods Software -- Custom Software Services
> > http://www.deepsoft.com/ -- Linux Administration Services
> > hel...@deepsoft.com -- Webhosting Services
> >
> >
> 

-- 
Robert Heller             -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software        -- Custom Software Services
http://www.deepsoft.com/  -- Linux Administration Services
hel...@deepsoft.com       -- Webhosting Services
                                                           

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