File content as of revision 0:cb5d20585be4:

#include "mbed.h"

DigitalOut tx(D15);

Serial pc(USBTX, USBRX); // tx, rx

void blink_binary(char c)
{
    for (int i = 7; i >= 0; --i) {
        tx = 0;
        wait_ms(10);
        tx = 1;
        wait_ms((c & (1 << i)) ? 20 : 10);
        tx = 0;
    }
    wait_ms(30);
}

int main()
{
    char* teststr = "Hello World\r\n";
    int testlen = strlen(teststr);
    
    pc.printf("3 CM Link Board - Transmit\r\n");
    char buffer[100];
    int idx = 0;
    while(1) {
        char a = pc.getc();
        if(a != '\n' && idx < 100){
            buffer[idx] = a;
            idx++;
        }else{
            for(int i=0;i<idx;i++){
                blink_binary(buffer[i]);
            }
            blink_binary('\r');
            blink_binary('\n');
            idx = 0;
        }
        
        
        
        /*
        for(int i=0;i<testlen;i++){
            blink_binary(teststr[i]);
        }
        */
    }
}