ARM development board to realize the up and down or so four buttons (corresponding to 1, 2, 3, 4), press the key on the digital tube display 1, the first LED lights, a serial port to print 1;
ARM development board to realize the up and down or so four buttons (corresponding to 1, 2, 3, 4), press the button on the digital tube display, 2 second LED lights, a serial port to print 2;
ARM development board to realize the up and down or so four buttons (1, 2, 3, 4), respectively, according to the left on the digital tube display 3, 3 LED lights, a serial port to print 3;
ARM development board to realize the up and down or so four buttons (corresponding to 1, 2, 3, 4), right click on the digital tube display 4, 4 LED lights, a serial port to print 4;