【平头哥Sipeed LicheeRV 86 Panel测评】十二、lvgl和pthread实现TCP Client

sonicfirr 发表于 2022-4-17 15:34

本帖最后由 sonicfirr 于 2022-4-17 15:40 编辑

上篇利用fork()创建子进程的形式实现TCP连接后的数据包接收，本篇则采用子线程的形式实现相同功能，利用线程间便捷的通信能力，将接收到信息通过lvgl控件显示出来。

<h2 style="text-align:justify">1、lvgl结合Linux线程</h2>

来自于lvgl官网在线文档（https://docs.lvgl.io/master/porting/os.html#tasks-and-threads）的介绍，为了保证lvgl内核运行后，对屏幕的及时刷新和输入设备的读取，操作系统模式下，需要通过互斥量来保护lvgl的lv_task_handler()和其它功能函数。

 



图12-1 lvgl关于任务和线程的文档截图

 

<h2 style="text-align:justify">2、TCP Client多线程案例</h2>

本例业务逻辑与上篇类似，lvgl展示主界面，包含一个按钮，点击后功能为：连接TCP Server；创建定时器周期发送信息；创建子线程做TCP接收。

lvgl的内核运行也封装在一个子线程中，即本例建立两个线程，一个应用开启即创建并用于UI刷新，一个点击按钮连接TCP后创建用于做接收并将接收到字串做控制台输出和屏幕显示（通过label）。

 

<pre>
<code>/* Includes ------------------------------------------------------- */
#include "lvgl/lvgl.h"
#include "lv_drivers/display/fbdev.h"
#include "lv_drivers/indev/evdev.h"
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

/* Private macro -------------------------------------------------- */
#define AITA_DISP_BUF_SIZE (128 * 1024)
#define AITA_SCREEN_WIDTH 480
#define AITA_SCREEN_HEIGHT 480
#define AITA_TITLE_STRING "AITA DEMO for LicheeRV with LVGL -- Thread"
#define N 128
#define OFF 0
#define ON 1
#define SERVER_IP "192.168.31.129"
#define SERVER_PORT 1234
#define SEND_PERIOD 1000
#define SEND_MSG "Hello World!\n"
#define errlog(errmsg) do{ perror(errmsg);\
printf("----%s----%s----%d----\n", __FILE__, __func__, __LINE__);\
return;\
} while(0)

/* Global variables ----------------------------------------------- */
lv_indev_t *aita_indev; //pointer of indev
lv_obj_t *sys_scr; //pointer of system screen instance
lv_obj_t *head_label; //pointer of title label instance
lv_obj_t *main_label; //pointer of main label instance
lv_obj_t *recv_label; //pointer of label instance for showing tcp recvdata
lv_obj_t *conn_btn; //pointer of conn button(tcp client) for instance
lv_obj_t *conn_btn_label; //pointer of label instance for conn button
lv_timer_t *tcp_timer; //pointer of timer instance for tcp polling
int conn_flag = OFF; //flag of tcp connect status
int sockfd; //socket file descriptor
struct sockaddr_in server;//tcp server ip;
socklen_t addrlen = sizeof(server);
int tcptimer_counter = 0; //send msg per (tcptimer_counter * SEND_PERIOD) ms
char recv_buf = ""; //recv buffer
pthread_t lvgl_tid; //lvgl thread id
pthread_t tcprecv_tid; //tcp receive thread id
pthread_mutex_t lvgl_mutex;

/* Private function prototypes ------------------------------------ */
void aita_InitLVGL(void);
void aita_CreateMainUI(void);
void aita_InitTimer(void);
void aita_InitSocket(void);
void conn_btn_click_cb(lv_event_t *e);
void tcp_timer_cb(lv_timer_t *timer);
void *thread_lvgl(void *arg);
void *thread_tcprecv(void *arg);

/* Private functions ---------------------------------------------- */
int main(void) {
void *retval;

//by author. initialize lvgl including displaybuffer, device for disp & input
aita_InitLVGL();

//by author. initialize and register event device
//these code must be in main(), otherwise the touch will fail
static lv_indev_drv_t indev_drv;
lv_indev_drv_init(&indev_drv);
indev_drv.type = LV_INDEV_TYPE_POINTER; //by author. choice touchpad
indev_drv.read_cb = evdev_read; //by author. input callback
aita_indev = lv_indev_drv_register(&indev_drv);

//by author. create the main view when the demo starts up
aita_CreateMainUI();

//by author. create a timer
aita_InitTimer();

//by author. create mutex for lvgl
if(pthread_mutex_init(&lvgl_mutex, NULL) != 0) {
 errlog("initialize mutex error");
}

//by author. create lvgl thread
if(pthread_create(&lvgl_tid, NULL, thread_lvgl, (void *)0) != 0) {
 errlog("create lvgl thread error");
}

//by author. wait for thread exit, this demo should never be here.
pthread_join(lvgl_tid, &retval);
printf("lvgl thread exit, return value: %s\n", (char *)retval);
pthread_mutex_destroy(&lvgl_mutex);
return 0;
}

/*Set in lv_conf.h as `LV_TICK_CUSTOM_SYS_TIME_EXPR`*/
uint32_t custom_tick_get(void)
{
static uint64_t start_ms = 0;
if(start_ms == 0) {
 struct timeval tv_start;
 gettimeofday(&tv_start, NULL);
 start_ms = (tv_start.tv_sec * 1000000 + tv_start.tv_usec) / 1000;
}

struct timeval tv_now;
gettimeofday(&tv_now, NULL);
uint64_t now_ms;
now_ms = (tv_now.tv_sec * 1000000 + tv_now.tv_usec) / 1000;

uint32_t time_ms = now_ms - start_ms;
return time_ms;
}

void aita_InitLVGL(void) {
/*LittlevGL init*/
lv_init();

/*Linux frame buffer device init*/
fbdev_init(); //by author. initialize framebuffer device for display
evdev_init(); //by author. initialize event device for touchpad

/*A small buffer for LittlevGL to draw the screen's content*/
static lv_color_t buf;
/*Initialize a descriptor for the buffer*/
static lv_disp_draw_buf_t disp_buf;
lv_disp_draw_buf_init(&disp_buf, buf, NULL, AITA_DISP_BUF_SIZE);
/*Initialize and register a display driver*/
static lv_disp_drv_t disp_drv;
lv_disp_drv_init(&disp_drv);
disp_drv.draw_buf = &disp_buf;
disp_drv.flush_cb = fbdev_flush;
disp_drv.hor_res = 480;
disp_drv.ver_res = 480;
lv_disp_drv_register(&disp_drv);
}

void aita_CreateMainUI(void) {
//by author. create system screen which is basic graphic level
sys_scr = lv_obj_create(lv_scr_act());
lv_obj_set_size(sys_scr, AITA_SCREEN_WIDTH, AITA_SCREEN_HEIGHT);
//by author. create the main title which is just a label
head_label = lv_label_create(sys_scr);
lv_label_set_text(head_label, AITA_TITLE_STRING);
lv_obj_align(head_label, LV_ALIGN_TOP_MID, 0, 50);

char main_label_text_buf;
sprintf(main_label_text_buf, "server ip:%s\nserver port:%d", SERVER_IP, SERVER_PORT);
main_label = lv_label_create(sys_scr);
lv_label_set_text(main_label, main_label_text_buf);
lv_obj_align(main_label, LV_ALIGN_CENTER, 0, -50);
lv_obj_set_style_text_font(main_label, &lv_font_montserrat_40, 0);

recv_label = lv_label_create(sys_scr);
lv_label_set_text(recv_label, "");
lv_obj_align(recv_label, LV_ALIGN_CENTER, 0, 20);

//by author. create the conn button for connecting a tcp server
conn_btn = lv_btn_create(sys_scr);
lv_obj_set_size(conn_btn, 200, 50);
lv_obj_align(conn_btn, LV_ALIGN_BOTTOM_MID, 0, -50);
//by author. register clicked-event callback for the "conn_btn" object
lv_obj_add_event_cb(conn_btn, conn_btn_click_cb, LV_EVENT_CLICKED, NULL);
conn_btn_label = lv_label_create(conn_btn);
lv_label_set_text(conn_btn_label, "Connect");
lv_obj_center(conn_btn_label);
}

//by author. tcp_timer callback which sends msg to server
void tcp_timer_cb(lv_timer_t *timer) {
if(send(sockfd, SEND_MSG, sizeof(SEND_MSG), 0) < 0) errlog("send error");
}
//by author. initialize timer for periodic sending
void aita_InitTimer(void) {
tcp_timer = lv_timer_create(tcp_timer_cb, 1000, NULL);
lv_timer_set_repeat_count(tcp_timer, -1);
lv_timer_pause(tcp_timer);
}

//by author. initialize the socket
void aita_InitSocket(void) {
if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) < 0) errlog("socket error");
server.sin_family = AF_INET;
server.sin_addr.s_addr = inet_addr(SERVER_IP);
server.sin_port = htons(SERVER_PORT);
printf("sockfd: %d\n", sockfd);
}

//by author. conn_btn callback which conn/disconn server
void conn_btn_click_cb(lv_event_t *e) {
printf("Conn Btn Clicked\n");
if(conn_flag == OFF) {
 aita_InitSocket();
 printf("server ip: %s, port: %d\n", SERVER_IP, SERVER_PORT);
 if(connect(sockfd, (struct sockaddr*)&server, addrlen) < 0) errlog("connect error");
 printf("connected\n");
 lv_timer_resume(tcp_timer);
 conn_flag = ON;
 lv_label_set_text(conn_btn_label, "Disconnect");
 //by author. create a thread for tcp recv
 if(pthread_create(&tcprecv_tid, NULL, thread_tcprecv, (void *)0) != 0) {
 errlog("create tcp receive thread error");
 }
} else {
 lv_timer_pause(tcp_timer);
 pthread_cancel(tcprecv_tid);
 close(sockfd);
 conn_flag = OFF;
 lv_label_set_text(conn_btn_label, "Connect");
}
}

//by author. lvgl core thread function
void *thread_lvgl(void *arg) {
while(1) {
 pthread_mutex_lock(&lvgl_mutex);
 lv_task_handler();
 pthread_mutex_unlock(&lvgl_mutex);
 usleep(5000); /* sleep for 5 ms */
}
}

//by author. tcp receive thread function
void *thread_tcprecv(void *arg) {
while(1) {
 if(read(sockfd, recv_buf, N) < 0) errlog("recv error");
 printf("server: %s\n", recv_buf);

 pthread_mutex_lock(&lvgl_mutex);
 lv_label_set_text(recv_label, recv_buf);
 pthread_mutex_unlock(&lvgl_mutex);

 memset(recv_buf, 0, N);
}
}</code></pre>

 



图12-2 案例效果展示

 

需要注意的是，子线程pthread库不是Linux系统默认的库，所以在编译项目时需要连接静态库libpthread.a，因而本例还需要修改Makefile，具体如下所示。

 



图12-3 增加-lpthread命令参数

Jacktang 发表于 2022-4-17 20:51

这个子线程pthread库不是Linux系统默认的库提醒很重要

sonicfirr 发表于 2022-4-17 21:12

Jacktang 发表于 2022-4-17 20:51
这个子线程pthread库不是Linux系统默认的库提醒很重要

还行吧，基本上不连接就会报错pthread相关函数未定义，一搜索很容易找到原因的。

谢谢，支持。

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【平头哥Sipeed LicheeRV 86 Panel测评】十二、lvgl和pthread实现TCP Client