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--- products:sbc:common:applications:gpio:irq [2022/06/29 21:51]
127.0.0.1 external edit
+++ products:sbc:common:applications:gpio:irq [2022/08/07 22:41] (current)
olivia [Introduction]
@@ Line 1: / Line 1: @@
-# IRQ
+====== GPIO Interrupts ======
+===== Introduction =====
+The page leads you to use GPIO interrupts with the GPIO number test program on Khadas SBC.
+<WRAP important >
+Here we use ''GPIOH_6'' on VIM3 as an example.
+</WRAP>
+===== Hardware Connection =====
+Connect the physical pins ''PIN20'' and ''PIN15'' by using a DuPont line.
+===== System Configuration =====
+Get ''GPIOH_6'' number
+Refer to [[/products/sbc/vim4/applications/gpio/40pin-header|40-Pin Header]], the GPIO number you get is ''433''.
+Export GPIO
+```shell
+$ echo 433 | sudo tee /sys/class/gpio/export
+```
+<WRAP info >
+Please use ''gpio readall'' to check the status of ''GPIOH_6'', if it is not shown as a normal GPIO, you need to remove ''uart3'' from ''overlays'' in file ''/boot/env.txt''. \\
+Check the [[products:sbc:vim4:configurations:device-tree-overlay|Device Tree Overlay]] for more details.
+</WRAP>
+===== Demo Source Code =====
+Get demo source code
+```c gpio_interrupts.c
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (c) 2022 Wesion Technology Co., Ltd.
+ *
+ * Author: Yan <yan-wyb@foxmail.com>
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <poll.h>
+#define SYSFS_GPIO_DIR  "/sys/class/gpio"
+#define MAX_BUF     255
+int gpio_export(unsigned int gpio){
+    int fd, len;
+    char buf[MAX_BUF];
+    fd = open(SYSFS_GPIO_DIR "/export", O_WRONLY);
+    if (fd < 0) {
+        fprintf(stderr, "Can't export GPIO %d pin: %s\n", gpio, strerror(errno));
+        return fd;
+    }
+    len = snprintf(buf, sizeof(buf), "%d", gpio);
+    write(fd, buf, len);
+    close(fd);
+    return 0;
+}
+int gpio_unexport(unsigned int gpio){
+    int fd, len;
+    char buf[MAX_BUF];
+    fd = open(SYSFS_GPIO_DIR "/unexport", O_WRONLY);
+    if (fd < 0) {
+        fprintf(stderr, "Can't unexport GPIO %d pin: %s\n", gpio, strerror(errno));
+        return fd;
+    }
+    len = snprintf(buf, sizeof(buf), "%d", gpio);
+    write(fd, buf, len);
+    close(fd);
+    return 0;
+}
+int gpio_set_edge(unsigned int gpio, char *edge){
+    int fd, len;
+    char buf[MAX_BUF];
+    len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/edge", gpio);
+    fd = open(buf, O_WRONLY);
+    if (fd < 0) {
+        fprintf(stderr, "Can't set GPIO %d pin edge: %s\n", gpio, strerror(errno));
+        return fd;
+    }
+    write(fd, edge, strlen(edge)+1);
+    close(fd);
+    return 0;
+}
+int gpio_set_pull(unsigned int gpio, char *pull){
+    int fd, len;
+    char buf[MAX_BUF];
+    len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/pull", gpio);
+    fd = open(buf, O_WRONLY);
+    if (fd < 0) {
+        fprintf(stderr, "Can't set GPIO %d pin pull: %s\n", gpio, strerror(errno));
+        return fd;
+    }
+    write(fd, pull, strlen(pull)+1);
+    close(fd);
+    return 0;
+}
+int main(int argc, char *argv[])
+{
+    struct pollfd fdset[2];
+    int fd, ret, gpio;
+    char buf[MAX_BUF];
+    if (argc < 3 || argc > 4)   {
+        fprintf(stdout, "usage : sudo sysfs_irq_test <gpio> <edge> [pull]\n");
+        fflush(stdout);
+        return  -1;
+    }
+    gpio = atoi(argv[1]);
+    if (gpio_export(gpio))  {
+        fprintf(stdout, "error : export %d\n", gpio);
+        fflush(stdout);
+        return  -1;
+    }
+    if (gpio_set_edge(gpio, argv[2])) {
+        fprintf(stdout, "error : edge %s\n", argv[2]);
+        fflush(stdout);
+        return  -1;
+    }
+    if (argv[3] && gpio_set_pull(gpio, argv[3])) {
+        fprintf(stdout, "error : pull %s\n", argv[3]);
+        fflush(stdout);
+        return  -1;
+    }
+    snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR "/gpio%d/value", gpio);
+    fd = open(buf, O_RDWR);
+    if (fd < 0)
+        goto out;
+    while (1) {
+        memset(fdset, 0, sizeof(fdset));
+        fdset[0].fd = STDIN_FILENO;
+        fdset[0].events = POLLIN;
+        fdset[1].fd = fd;
+        fdset[1].events = POLLPRI;
+        ret = poll(fdset, 2, 3*1000);
+        if (ret < 0) {
+            perror("poll");
+            break;
+        }
+        fprintf(stderr, ".");
+        if (fdset[1].revents & POLLPRI) {
+            char c;
+            (void)read (fd, &c, 1) ;
+            lseek (fd, 0, SEEK_SET) ;
+            fprintf(stderr, "\nGPIO %d interrupt occurred!\n", gpio);
+        }
+        if (fdset[0].revents & POLLIN)
+            break;
+        fflush(stdout);
+    }
+    close(fd);
+out:
+    if (gpio_unexport(gpio))    {
+        fprintf(stdout, "error : unexport %d\n", gpio);
+        fflush(stdout);
+    }
+    return 0;
+ }
+```
+Compile the source code
+```shell
+$ gcc -o gpio_interrupts gpio_interrupts.c
+```
+===== Demonstrate =====
+The test code running format is as follows:
+```shell
+$ sudo ./gpio_interrupts <edge> [pull]
+```
+Run test:
+```shell
+$ sudo ./gpio_interrupts rising down
+.
+GPIO 433 interrupt occurred!
+..
+GPIO 433 interrupt occurred!
+.
+GPIO 433 interrupt occurred!
+.
+GPIO 433 interrupt occurred!
+```

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