Raspberry Pi

[Raspberry Pi] Socket Programming and GPIO

文章目錄
  1. 目的
  2. Demo on Youtube
  3. Source code.

目的

很久之前, 曾經做過 socket programming在樹梅派的應用. 也做了個demo影片留在youtube上, 當初只是好玩做做,沒想到有人需要source code. 我找了一下, 所以就放上來了,有興趣的可以看一下囉，沒意外的話,應該也是一個拼裝車XDDD

這個Demo 影片, 是讓樹梅派當client, 讓laptop 當server 收訊號. 因爲我只有一個樹梅派, 但是我又想模擬mutlit-client的情況, 所以我在laptop又多起一個task去送訊號給server.

Demo on Youtube

This demo tell how to control GPIO and send the data to server. About socket programming, server can receive the data from multi client.

Source code.

下載Download

1. server端

// sr_server.c

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/*
Function : socket code for server
Arthur : SheldonRush Peng
Date : 2013/7/26
*/

#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>

int main(int argc, char *argv[])
{
    int connfd = 0, n = 0, listenfd = socket(AF_INET, SOCK_STREAM, 0);
    struct sockaddr_in serv_addr;

    char charBuff[1024];
    char recvBuff[1024];
    time_t ticks;

    // init the data structure of serv_addr
    memset(&serv_addr, '0', sizeof(serv_addr));
    memset(charBuff, '\0', sizeof(charBuff));
    memset(recvBuff, '\0', sizeof(recvBuff));

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(8998);

    // assign the scket port to socket
    bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

    listen(listenfd, 20);

    while (1)
    {
        connfd = accept(listenfd, (struct sockaddr*)NULL, NULL);
   
        printf("%s %d \n", "server: connfd is", connfd);
        ticks = time(NULL);
        snprintf(charBuff, sizeof(charBuff), "%s\n", ctime(&ticks));
        printf("server: %s\n", charBuff);
        
        while ( (n = read(connfd, recvBuff, sizeof(recvBuff)-1)) > 0)
        {
           recvBuff[n] = 0;
           printf("server: read %d bytes \n", n);
           printf("server: EOF = %d \n", EOF);
           if ( fputs(recvBuff, stdout) == EOF)
           {
                printf("Error : Fputs error \n");
           }
        }

        if (n < 0)
        {
            printf("Error : read errpr \n");
        }
       //  write(connfd, sendBuff, strlen(sendBuff));
        close(connfd);
        sleep(1); 
    }
}

2. Clinet 端

// main.c

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/*
Function : Detect whether GPIO[17] is high or low
Arthur : Sheldon RUsh Peng
Date : 2013/7/27
*/

#include <wiringPi.h>
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include "sr_clinit.h" 


#define False 0
#define True 0
#define pin 0 //GPIO[17]

int main(int argc, char *argv[])
{
    int pin_value = False;
    time_t current_time;
    int count = 0;
    
    if (argc != 4)
    {
        printf("Usage : %s <ip> <port> <station id> \n", argv[0]);
        return 1;
    }
  
    if (-1 == wiringPiSetup())
        exit(1);

    // init GPIO[17] to be INPUT port 
    pinMode(pin, INPUT);
    
    while (1)
    {
        current_time = time(NULL); 
        pin_value = digitalRead(pin);
        if (True == pin_value)
        {
            count ++;
            printf("\n\n%s\n", ctime(&current_time));
            printf("Work station call help [%d] time\n", count);
            
            if (0 != socket_clinit_main(argc,argv))
            {
                printf("cannot call help \n");
                return 1;
            }
            sleep(5);
        }
    }
}

// sr_clinit.h 

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extern int socket_clinit_main(int argc, char *argv[]);

// sr_clinit.c 

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/*
Function : Socket code for clinit
Arthur : SheldonRush Peng
Date : 2013/7/26
*/

#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <stdio.h>
#include "sr_clinit.h"

int socket_clinit_main(int argc, char *argv[])
{
    int sockfd = 0, n = 0;
    char sendBuff[1024];

    struct sockaddr_in serv_addr;

    if (argc != 4)
    {
        printf("Usage : %s <ip> <port> <station id>\n", argv[0]);
        return 1;
    }
    
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        printf("Error : cannot create a socket\n"); 
        return 1;
    }
    memset(sendBuff, '\0', sizeof(sendBuff));
    
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(atoi(argv[2]));

    if (inet_pton(AF_INET, argv[1], &serv_addr.sin_addr) <= 0 )
    {
        printf("%s \n" , " Error : cannot convert text to ip binary");
        return 1;
    }

    if ( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0 )
    {
        printf("Error : canot connect server\n");
    }

    printf("Clinit: Send data to server, station id = %d\n", atoi(argv[3]));
    snprintf(sendBuff,  sizeof(sendBuff), "hi Sheldon, I am station id [%d]\n", atoi(argv[3]));
    printf("Clint: data is {%s}\n", sendBuff);
    write(sockfd, sendBuff, strlen(sendBuff));

    close(sockfd);
/*
    while ( (n = read(sockfd, recvBuff, sizeof(recvBuff)-1)) > 0)
    {
        recvBuff[n] =0;
        if ( fputs(recvBuff, stdout) == EOF)
        {
           printf("Error : Fputs error \n");
        }
    }

   if (n < 0)
   {
        printf("Error : read error \n");
        return 1;
   }
*/
   return 0;
}