C RbPi UART Remote Control Sockets - c

Question

I want to remote control sockets in my room manual without an extra library on my raspberry pi. I want to use the UART interface in C. The socket has 433 Mhz receiver and I use a 433 Mhz transmitter. In other librarys you type something like this: send 11111 1 1. (socket code, socket number, condition). But how to format this command in C with the write() function? The 10 is for number of characters. I use this code below. I tested the output via minicom, that works fine. But how the receiver now knows that it was adressed?
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
int main(int argc, char ** argv) {
int fd;
// Open the Port. We want read/write, no "controlling tty" status, and open i$
fd = open("/dev/ttyAMA0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror("open_port: Unable to open /dev/ttyAMA0 - ");
return(-1);
}
// Turn off blocking for reads, use (fd, F_SETFL, FNDELAY) if you want that
fcntl(fd, F_SETFL, 0);
// Write to the port
int n = write(fd,"11111 1 1",10);
if (n < 0) {
perror("Write failed - ");
return -1;
}
// Don't forget to clean up
close(fd);
return 0;
}

Answer 1

Do I get it right: you send a command via UART to transmit a message via radio trasmitter. Sniffing the UART output proves your code OK in the sense that TX line sends what you want it to send in the software, and the actual question is "how the rx module gets that message/how to make the rx module get it?"
If so, the main question is what kind of radio TX/RX or TRXs do you actually use (I mean chip/module codes, like CC1120, NRF2401 etc.)? There are plenty of 433MHz radiomodules available, I suppose consulting their datasheet first or at least posting the part number here is the right way to go.