File content as of revision 4:eabf5656c755:

#include "mbed.h"                             //Preprocessor Directives 
                                              // Declarations 
Serial pc(USBTX, USBRX); // tx, rx  
PwmOut led(LED1);

float brightness = 0.0;
int main() {                                    //instructions in main () function 
    pc.printf("Press 'u' to turn LED1 brightness up, 'd' to turn it down\n");
    
    while(1) {
        char c = pc.getc(); //Reads a character from keyboard
        if((c == 'u') && (brightness < 0.5)) {
            brightness += 0.01;
            led = brightness;
            pc.putc('^'); // Writes a character ('^') to the standard output
        }
        if((c == 'd') && (brightness > 0.0)) {
            brightness -= 0.01;
            led = brightness;
            pc.putc('v'); // Writes a character  ('v') to the standard output
        }
    }
}