#include "mbed.h" DigitalOut led1(LED1); DigitalOut led2(LED2); Serial computer(USBTX, USBRX); // This function is called when a character goes into the TX buffer. void txCallback() { led1 = !led1; } // This function is called when a character goes into the RX buffer. void rxCallback() { led2 = !led2; computer.putc(computer.getc()); } int main() { printf("start test\n"); computer.attach(&txCallback, Serial::TxIrq); computer.attach(&rxCallback, Serial::RxIrq); while (true) { wait(1); } }