c-cpp on Purinda Gunasekara

Weekend Project: Pi Music Box – Raspberry Pi as a Music streaming device

Sun, 08 Dec 2013 18:58:37 +1100

Get Grooveshark to run on a Raspberry Pi, Let your friends connect to and vote for their favourite songs. Let the majority rule what you hear at home or office.

We used to play songs regularly at work. Most of the time I play Dubstep while rest of the team want to listen to Trance or a different genre, this is where the clash of genres occur. This is where this system would be useful, if you get this running on a network then you can ask people to search their favourite songs and queue them in the system. Based on the votes they/others make for the song, it may float up or down making it either famous or not-so-famous. This makes a playlist of highest voted or popular songs.

How to check if a Port is open or not in C (Unix/Linux)

Mon, 30 Sep 2013 12:21:04 +1000

Thought of posting this script as I found this useful to embed in any socket based programs to figure out if a port is open or not in a certain host.
Tested on a Linux box and appears to be working fine.

Localhost and port 22 is hard coded into the snippet.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

int main(int argc, char *argv[])
{
    int portno     = 22;
    char *hostname = "localhost;

    int sockfd;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        error("ERROR opening socket");
    }

    server = gethostbyname(hostname);

    if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr,
         (char *)&serv_addr.sin_addr.s_addr,
         server->h_length);

    serv_addr.sin_port = htons(portno);
    if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) {
        printf("Port is closed");
    } else {
        printf("Port is active");
    }

    close(sockfd);
    return 0;
}

Beaglebone RF24(nRF24L01) Library

Thu, 09 Aug 2012 15:15:45 +0000

Why?

I started working on a project which require communication with multiple radios. I started looking at nRF24L01 chip and found it to be very useful, cheap little device which has many features built-in. Initially I got two AVRs to talk to each other through the simple library found here (http://www.tinkerer.eu/AVRLib/nRF24L01). But I found multiple issues with the library when the number of nodes in the network increases,