USB Native Serial port on Arduino Micro

Dear All, I 'm working on a project that need to communicate with the Arduino board Micro ( i need extra serial port on the Micro board for other function). The idea is just simple: PC send out a byte to the Arduino Micro, the board will put that number to the formula then bound back the result to the PC. I made my own software on PC by Visual Studio VB 2012 express. just like this: https://code.msdn.microsoft.com/windowsapps/SerialPort-Sample-in-VBNET-fb040fb2 You can download the code there too

when I test by serial console test on Arduino IDE, it works fine as expected. But with my software there is no respond, my software got nothing respond from the Micro board.

Then i try with the Arduino Nano board instead, both serial console on the arduino IDE and my software can communicate with the board as expected.

The difference between the the Nano and Micro is: On the Nano, there is a USB - UART converter. On the Micro, the USB serial is native. I have no idea how to make my software to talk with the Micro board. I do further test by use my software to send out a byte to the Micro board to lid up the LED, it work fine. So that mean the software I made can send a byte to the Micro board but not receive. Strange thing is why my VB software can communicate with the Nano board but not the Micro board. And the Arduino Serial console can communicate with both boards.

Thanks for your help! Cuong

And the Arduino Serial console can communicate with both boards.

The Serial Monitor application uses DTR=on in the serial port initialization process. The default for DTR is off. The DTR value must be on to communicate with the Leonardo and the Micro.

PaulS: The Serial Monitor application uses DTR=on in the serial port initialization process. The default for DTR is off. The DTR value must be on to communicate with the Leonardo and the Micro.

I just fixed my software with the DTR ON as you said when init the port. It works as expected now.

Thanks a lot PaulS.

Cuong.