Allwinner v851s GPIO application programming

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Allwinner v851s GPIO application programming [Copy link]

**1. Check the hardware circuit diagram SCH_Schematic1_2022-11-23 and find the appropriate gpio as the pin to be used** Here we select GPIOH14 (note that this pin is currently used as the pin of the touch screen, and the touch screen needs to be disconnected), because it can be led out through the power strip using a Dupont line for connecting other devices. Circuit diagram pdf path: Yuzukilizard/Hardware/Schematic/SCH_Schematic1_2022-11-23.pdf 
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 **2. Calculate the gpio IO number** In the Linux system, GPIO is usually managed by the Pinctrl system. Linux defines the Pinctrl framework, which unifies the Pin management methods of major SoC manufacturers, avoiding major manufacturers from implementing their own Pin management systems, which is a very useful function. Each gpio corresponds to an IO number: PH14: 7 * 32 + 14 = 238 PH13: 7 * 32 + 13 = 237 PH12: 7 * 32 + 12 = 236 PH11: 7 * 32 + 11 = 235 **3. Export gpio node through sysfs operation** Manually export through terminal operation: ``` echo 238 > /sys/class/gpio/export ``` View the exported gpio node``` cd /sys/class/gpio ``` You can see that if gpio238 is exported through the application, the code is as follows: ``` #include<sys stat.h="">
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<errno.h>
#include<unistd.h>
#include<fcntl.h>
#include<poll.h>

#define GPIOH14 238 #define XGPIO_HIGH 1 #define XGPIO_LOW 0 /****************************************** *************************** * Constants ********************* *******************************************/ #define SYSFS_GPIO_DIR "/sys /class/gpio" #define POLL_TIMEOUT (3 * 1000) /* 3 seconds */ #define MAX_BUF 64 /************************** ************************************ * gpio_export ************ *************************************************** ****/ int gpio_export(unsigned int gpio) { int fd, len; char buf[MAX_BUF]; fd = open(SYSFS_GPIO_DIR"/export", O_WRONLY); printf("open device ===================fd = %d\n", fd); if (fd < 0) { printf("gpio/export\n"); return fd; } len = snprintf(buf, sizeof(buf), "%d", gpio); write(fd, buf, len); close(fd); return 0; } ``` It is very important to export the gpio node according to the IO number Next, you can operate the gpio through the gpio node. 4. Next, set the output state of the gpio and set its high and low levels. The complete code is as follows: ``` #include<sys stat.h="">
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<errno.h>
#include<unistd.h>
#include<fcntl.h>
#include<poll.h>

#include "gpioAPIs.h" /****************************************** ************************ * Constants **************************** ****************************************/ #define SYSFS_GPIO_DIR "/sys/class/gpio" #define POLL_TIMEOUT (3 * 1000) /* 3 seconds */ #define MAX_BUF 64 /********************************** ********************************* * gpio_export *************** *************************************************/ int gpio_export(unsigned int gpio) { int fd, len; char buf[MAX_BUF]; fd = open(SYSFS_GPIO_DIR"/export", O_WRONLY); printf("open device ============= =====fd = %d\n", fd); if (fd < 0) { printf("gpio/export\n"); return fd; } len = snprintf(buf, sizeof(buf), "%d", gpio); write(fd, buf, len); close (fd); return 0; } /***************************************** ************************* *gpio_unexport ************************* ***************************************/ int gpio_unexport(unsigned int gpio) { int fd , len; char buf[MAX_BUF]; fd = open(SYSFS_GPIO_DIR"/unexport", O_WRONLY); if (fd < 0) { printf("gpio/export\n"); return fd; } len = snprintf(buf, sizeof(buf), "%d", gpio); write(fd, buf, len); close(fd); return 0; } /****************************************** ************************ * gpio_set_dir ************************ ******************************************/ int gpio_set_dir(unsigned int gpio, unsigned int out_flag) { int fd, len; char buf[MAX_BUF]; len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR"/gpio%d/direction", gpio); fd = open(buf, O_WRONLY); if (fd < 0) { printf("gpio/direction\n"); return fd; } if (out_flag) write(fd, "out", 4); else write(fd, "in", 3); close(fd) ; return 0; } /******************************************** ********************* * gpio_set_value ************************************************* ***************/ int gpio_set_value(unsigned int gpio, unsigned int value) { int fd, len; char buf[MAX_BUF]; len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR"/gpio%d/value", gpio); fd = open(buf, O_RDWR ); if (fd < 0) { printf("gpio/set-value\n"); return fd; } if (value) write(fd, "1", 2); else write(fd, "0", 2); close(fd); return 0; } /************************ *********************************************** * gpio_get_value * *************************************************** *************/ int gpio_get_value(unsigned int gpio, unsigned int *value) { int fd, len; char buf[MAX_BUF]; char ch; len = snprintf(buf, sizeof(buf), SYSFS_GPIO_DIR"/gpio%d/value", gpio); fd = open (buf,O_RDWR ); if (fd < 0) { printf("gpio/get-value\n"); return fd; } read(fd, &ch, 1); if (ch != '0') { *value = 1 ; } else { *value = 0; } close(fd); return 0; } /****************************** ********************************** *gpio_set_edge ****************** *************************************************** / 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) { printf("gpio/set-edge\n"); return fd; } write(fd, edge, strlen(edge) + 1); close(fd); return 0; } /******** *************************************************** ***** * gpio_fd_open ******************************************* *********************/ int gpio_fd_open(unsigned int gpio) { int fd, len; char buf[MAX_BUF]; len = snprintf(buf, sizeof(buf ), SYSFS_GPIO_DIR"/gpio%d/value", gpio); fd = open(buf, O_RDONLY | O_NONBLOCK ); if (fd < 0) { printf("gpio/fd_open\n"); } return fd; } / *************************************************** ******************* gpio_fd_close ************************************************** ***************/ int gpio_fd_close(int fd) { return close(fd); } void gpio_init() { gpio_export(GPIOH14); gpio_set_dir(GPIOH14, 0); //gpio_set_edge (GPIOH14, "rising"); } void gpio_uninit() { gpio_unexport(GPIOH14); } void mian(void) { gpio_init(); //Set gpio238 to high level output gpio_set_value(GPIOH14, XGPIO_HIGH ); // Set gpio238 to low level output gpio_set_value(GPIOH14, XGPIO_LOW); } ``` Original text from Allwinner Online Developer CommunityO_RDONLY | O_NONBLOCK ); if (fd < 0) { printf("gpio/fd_open\n"); } return fd; } /********************** ***************************************** * gpio_fd_close ***** *************************************************** *********/ int gpio_fd_close(int fd) { return close(fd); } void gpio_init() { gpio_export(GPIOH14); gpio_set_dir(GPIOH14, 0); //gpio_set_edge(GPIOH14, "rising" ); } void gpio_uninit() { gpio_unexport(GPIOH14); } void mian(void) { gpio_init(); //Set gpio238 to high level output gpio_set_value(GPIOH14, XGPIO_HIGH ); //Set gpio238 to low level output gpio_set_value(GPIOH14, XGPIO_LOW); } ``` Original text from Allwinner Online Developer CommunityO_RDONLY | O_NONBLOCK ); if (fd < 0) { printf("gpio/fd_open\n"); } return fd; } /************************ ******************************************* * gpio_fd_close ***** *************************************************** *********/ int gpio_fd_close(int fd) { return close(fd); } void gpio_init() { gpio_export(GPIOH14); gpio_set_dir(GPIOH14, 0); //gpio_set_edge(GPIOH14, "rising" ); } void gpio_uninit() { gpio_unexport(GPIOH14); } void mian(void) { gpio_init(); //Set gpio238 to high level output gpio_set_value(GPIOH14, XGPIO_HIGH ); //Set gpio238 to low level output gpio_set_value(GPIOH14, XGPIO_LOW); } ``` Original text from Allwinner Online Developer Community</poll.h></fcntl.h></unistd.h></errno.h></string.h></stdlib.h></stdio.h></sys></poll.h></fcntl.h></unistd.h></errno.h></string.h></stdlib.h></stdio.h></sys>

火辣西米秀

Linux's GPIO is managed by the Pinctrl system, and each major manufacturer implements its own Pin management. This is convenient

Allwinner v851s GPIO application programming [Copy link]

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