12 years, 8 months ago.

Serial communication with PC Led brightness not functioning

I am a raw newbie trying to get a handle on issues related to serial communication, and so I downloaded another mbed example from the Serial Communication with PC section of the handbook. Here is the code:

1. include "mbed.h"

Serial pc(USBTX, USBRX); tx, rx PwmOut led(LED1);

float brightness = 0.0;

int main() { pc.printf("Press 'u' to turn LED1 brightness up, 'd' to turn it down\n");

while(1) { char c = pc.getc(); if((c == 'u') && (brightness < 0.5)) { brightness += 0.01; led = brightness; } if((c == 'd') && (brightness > 0.0)) { brightness -= 0.01; led = brightness; }

} }

After the compile and download, in the terminal program the "Press 'u' to turn...." is displayed, and each press on the keyboard on my laptop causes a flicker on the mbed circuit board, but the brightness of the LED is unaffected.

Can someone explain why the LED remains bright all the time and does not do what is expected?