On Tue, 11 May 2021 09:43:49 -0700, in gmane.comp.hardware.beagleboard.user
"John Dammeyer" <[email protected]> wrote:
>To try this program do sudo apt install lazarus.
>
I think not... Not for an experiment at least. No offence intended, but
it wants to install over 1GB of stuff -- which is a 33% increase in the
content of my uSD card!, and would require me to attach a keyboard and
display to work with the GUI.
Now, a simple command line only program would be a different matter
(does FPC support command line only? -- FPC may be small enough to justify
installing for testing via SSH, but not Lazarus... *** nope, just FPC is
most of the load, 900+MB)
An example using GNAT (Ada). There is no (or I don't know of one)
library for GPIO access in GNAT Ada, so everything is SysFS I/O. I had to
set the pin number to string as the simple integer'image(pin) was
generating leading spaces, which resulted in invalid file name. Everything
is in one (117 line) file -- no nasty forms, etc.
debian@beaglebone:~/BBB_IO$ ls
main.adb
debian@beaglebone:~/BBB_IO$ cat main.adb
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Main is
Sysfs_Path : constant String := "/sys/class/gpio";
GPIO_Pin : constant String := "48";
Pin_Value : Integer;
procedure Export_Pin (Pin : in String) is
Export_File : File_Type;
Export_Path : constant String := Sysfs_Path & "/export";
begin
Put_Line ("Opening " & Export_Path);
Open (Export_File, Mode => Out_File, Name => Export_Path);
Put_Line ("Writing pin number: " & Pin);
Put (Export_File, Pin);
Put_Line ("Closing " & Export_Path);
Close (Export_File);
New_Line;
end Export_Pin;
procedure Set_Direction (Pin : in String; Direction : in String) is
Pin_File : File_Type;
Pin_Path : constant String := Sysfs_Path & "/gpio" & Pin &
"/direction";
begin
Put_Line ("Opening " & Pin_Path);
Open (Pin_File, Mode => Out_File, Name => Pin_Path);
Put_Line ("Writing direction: " & Direction);
Put (Pin_File, Direction);
Put_Line ("Closing " & Pin_Path);
Close (Pin_File);
New_Line;
end Set_Direction;
procedure Set_Value (Pin : in String; Value : in Integer) is
Pin_File : File_Type;
Pin_Path : constant String := Sysfs_Path & "/gpio" & Pin & "/value";
begin
Put_Line ("Opening " & Pin_Path);
Open (Pin_File, Mode => Out_File, Name => Pin_Path);
Put_Line ("Writing value: " & Integer'Image (Value));
Put (Pin_File, Value, Width => 1);
Put_Line ("Closing " & Pin_Path);
Close (Pin_File);
New_Line;
end Set_Value;
procedure Get_Value (Pin : in String; Value : out Integer) is
Pin_File : File_Type;
Pin_Path : constant String := Sysfs_Path & "/gpio" & Pin & "/value";
In_Value : String := " ";
begin
Put_Line ("Opening " & Pin_Path);
Open (Pin_File, Mode => In_File, Name => Pin_Path);
Put_Line ("Reading value");
Get (Pin_File, Value, Width => 0);
Put_Line ("Closing " & Pin_Path);
Close (Pin_File);
New_Line;
end Get_Value;
begin
-- Believe the pins are already exported in Buster
--Export_Pin (Gpio_Pin);
Get_Value (GPIO_Pin, Pin_Value);
Put_Line
("Current value of " & GPIO_Pin & " is " & Integer'Image (Pin_Value));
New_Line;
Set_Direction (GPIO_Pin, "out");
New_Line;
Get_Value (GPIO_Pin, Pin_Value);
Put_Line
("Current value of " & GPIO_Pin & " is " & Integer'Image (Pin_Value));
New_Line;
Set_Value (GPIO_Pin, 0);
Get_Value (GPIO_Pin, Pin_Value);
Put_Line
("Current value of " & GPIO_Pin & " is " & Integer'Image (Pin_Value));
New_Line;
Set_Value (GPIO_Pin, 1);
Get_Value (GPIO_Pin, Pin_Value);
Put_Line
("Current value of " & GPIO_Pin & " is " & Integer'Image (Pin_Value));
end Main;
debian@beaglebone:~/BBB_IO$
debian@beaglebone:~/BBB_IO$ gnatmake main
arm-linux-gnueabihf-gcc-8 -c main.adb
arm-linux-gnueabihf-gnatbind-8 -x main.ali
arm-linux-gnueabihf-gnatlink-8 main.ali
debian@beaglebone:~/BBB_IO$
debian@beaglebone:~/BBB_IO$ ls
main main.adb main.ali main.o
debian@beaglebone:~/BBB_IO$
debian@beaglebone:~/BBB_IO$ ./main
Opening /sys/class/gpio/gpio48/value
Reading value
Closing /sys/class/gpio/gpio48/value
Current value of 48 is 1
Opening /sys/class/gpio/gpio48/direction
Writing direction: out
Closing /sys/class/gpio/gpio48/direction
Opening /sys/class/gpio/gpio48/value
Reading value
Closing /sys/class/gpio/gpio48/value
Current value of 48 is 0
Opening /sys/class/gpio/gpio48/value
Writing value: 0
Closing /sys/class/gpio/gpio48/value
Opening /sys/class/gpio/gpio48/value
Reading value
Closing /sys/class/gpio/gpio48/value
Current value of 48 is 0
Opening /sys/class/gpio/gpio48/value
Writing value: 1
Closing /sys/class/gpio/gpio48/value
Opening /sys/class/gpio/gpio48/value
Reading value
Closing /sys/class/gpio/gpio48/value
Current value of 48 is 1
debian@beaglebone:~/BBB_IO$
Again, under a Buster IoT image (no X-Window overhead), NO SUDO NEEDED
FOR GPIO48 -- and it is already exported so I could even skip the export
call.
I'm not going to try to configure a SPI device for testing.
--
Dennis L Bieber
--
For more options, visit http://beagleboard.org/discuss
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