Difference between revisions of "Gpio beaglebone black"
From Teknologisk videncenter
m (→GPIOD version 1.4.1) |
m (→native config-pin command) |
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| + | =Linux pin controller terminology= | ||
| + | ;pinctl: Does enumeration of pins, groups of pins and GPIO range cross-referencing. | ||
| + | ;pinmux: Multiplexes accress different uses of pins. | ||
| + | ;pinconf: Configures electrical characteristics of pins. | ||
=native config-pin command= | =native config-pin command= | ||
<source lang=bash> | <source lang=bash> | ||
| Line 6: | Line 10: | ||
</source> | </source> | ||
P9_16 (gpio 51) configure to gpio mode configured as input with pull-up resistor. Current input value "0". | P9_16 (gpio 51) configure to gpio mode configured as input with pull-up resistor. Current input value "0". | ||
| + | |||
=libgpiod Library= | =libgpiod Library= | ||
See: [https://www.ics.com/blog/gpio-programming-exploring-libgpiod-library exploring libgpiod library] | See: [https://www.ics.com/blog/gpio-programming-exploring-libgpiod-library exploring libgpiod library] | ||
Latest revision as of 11:59, 12 May 2024
Contents
Linux pin controller terminology
- pinctl
- Does enumeration of pins, groups of pins and GPIO range cross-referencing.
- pinmux
- Multiplexes accress different uses of pins.
- pinconf
- Configures electrical characteristics of pins.
native config-pin command
debian@beaglebone:/sys$ config-pin P9_16 gpio_pu
debian@beaglebone:/sys$ config-pin -q P9_16
P9_16 Mode: gpio_pu Direction: in Value: 0
P9_16 (gpio 51) configure to gpio mode configured as input with pull-up resistor. Current input value "0".
libgpiod Library
See: exploring libgpiod library
install the libgpiod library if not installed.
- gpiodetect
- List all GPIO chips present on the system, their names, labels and number of GPIO lines.
- gpioinfo
- List all lines of specified GPIO chips, their names, consumers, direction, active state and additional flags.
- gpioget
- Read values of specified GPIO lines.
- gpioset
- Set values of specified GPIO lines, and potentially keep the lines exported and wait until timeout, user input or signal.
- gpiofind
- Find the GPIO chip name and line offset given the line name.
- gpiomon
- Wait for events on GPIO lines, specifying which events to watch, how many events to process before exiting or if the events should be reported to the console.
gpioset example
The following sets line 18 on chip 2 to 1 in three seconds.
gpioset --mode=time -s 3 2 18=1
gpioget
The following reads state of line 19 in chip 2
gpioget 2 19
1
GPIOD version 1.4.1
/*
Install libgpiod-dev and libgpiod-doc for development
compile with -lgpiod
See: https://www.ics.com/blog/gpio-programming-exploring-libgpiod-library
Hardware: Beaglbone Black with Seeed studio Grove cape and Blue LED
button in GPIO_50 Digital I/O.
*/
#include <gpiod.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char **argv)
{
const char *chipname = "gpiochip1";
struct gpiod_chip *chip;
struct gpiod_line *lineBlue; // Red LED
struct gpiod_line *lineButton; // Pushbutton
int i, val;
printf("GPIOD version: %s\n", gpiod_version_string());
// Open GPIO chip
chip = gpiod_chip_open_by_name(chipname);
if (chip == 0) {
fprintf(stderr," ERROR gpiod_chip_open_by_name() failed\n");
return(1);
}
printf("kernel name for gpiochip1: %s\n",gpiod_chip_name(chip));
// Open GPIO lines
lineBlue = gpiod_chip_get_line(chip, 18); // Grove cape it's called 50
if (lineBlue == 0) {
fprintf(stderr," ERROR gpiod_get_line() failed: lineBlue\n");
return(1);
}
lineButton = gpiod_chip_get_line(chip, 19); // Grove cape it's called 51
if (lineButton == 0) {
fprintf(stderr," ERROR gpiod_get_line() failed: lineButton\n");
return(1);
}
// Open LED lines for output
gpiod_line_request_output(lineBlue, "lineBlue", 1);
// Open switch line for input
gpiod_line_request_input(lineButton, "LineButton");
// Blink LED
i = 0;
while (true) {
gpiod_line_set_value(lineBlue, (i & 1) != 0);
// Read button status and exit if pressed
val = gpiod_line_get_value(lineButton);
if (val == 0) {
printf("FINISHED with count %d\n",i);
break;
}
usleep(100000);
i++;
}
// Release lines and chip
gpiod_line_release(lineBlue);
gpiod_line_release(lineButton);
gpiod_chip_close(chip);
return 0;
}