SocketCAN continuous reading and writing

PaulPonomarev picture PaulPonomarev · Jan 15, 2014 · Viewed 13.4k times · Source

I'm writing a program that continuously sends "Hello" to a CAN-bus and reads data from the bus via SocketCAN. I want those two steps to be independent. That means even if there is no data on the bus, the program will still send "Hello". But with usual CAN reading it is impossible, because this function stops program run and waits for data.

Is there a way how to make it non-blocking or waiting for data only for a few milliseconds?

Answer

PaulPonomarev picture PaulPonomarev · Jan 16, 2014

Another way I found - threads. Just make CAN reading work in thread and it won't stop main cycle. For Linux systems it looks like this:

 #include <pthread.h>

    void *thread(int cansock) {
       struct can_frame rxmsg;      
       while (1) {   
            read(cansock, &rxmsg, sizeof(rxmsg));
            printf("message received\n");                     
        }
    }

    int main(){
// initialize CAN socket and message to send
    pthread_t pth;
    pthread_create(&pth, NULL, thread, cansock);
    while(1){
      write(cansock, &txmsg, sizeof(txmsg));
      printf("message sent\n");
      }
    return 0;
    }