PL2303 and Arduino Uno/Mega

Hello.
I have a USB UART converter.


I connect it to the Arduino Uno as follows:
5V<->5V
GND<->GND
RX<->RX
TX<->TX
An error occurs when loading the sketch: programmer is not pesponding.
How can I upload a sketch through USB UART?

SergeyAndSmart:
RX<->RX
TX<->TX

should be:
RX<->TX
TX<->RX

This is because RX stands for “receive” and TX stands for “transmit”.

You also need to reset the board at just the right time to do the upload. Usually this is done automatically by connecting the DTR or CTS pin of the USB-UART chip to the reset pin of the Arduino board. Since your PL2303 doesn’t have one of those pins broken out (at least the one I have that looks identical doesn’t) you will need to manually reset the Arduino. This is what you need to do:

  • In the Arduino IDE do File > Preferences > Show verbose output during: > upload (check) > OK
  • Start the upload
  • Watch the black console window at the bottom of the Arduino IDE window (you will probably want to resize it larger than the default size). As soon as you see the upload process begin press the reset button on the Arduino Uno/Mega. You don’t want to do it too soon because there is only a short amount of time that the bootloader is activated for uploads to begin.

Why do you want to do this? You do know that the Uno and Mega boards already have a USB to serial chip and you can just upload over the USB jack on the board, right? No need to use that PL2303 breakout. If you are going to mess with that sort of thing I really recommend you to buy an FTDI FT232 breakout instead. You can get them for <$2 USD w/ free shipping and they have the DTR pin to do the automatic reset. They are set up to be able to plug into the Pro Mini or any other board that uses the standard FTDI header pinout. You may get a counterfeit one if you buy the super cheap ones but they will work fine, you may have to work a little magic to get around the official driver if you’re using Windows but it’s just a matter of installing a different driver that supports the counterfeits.

Everything works, thank you. And I need it because the distance from the PC to the Arduino large, and the USB cable is short.

With Arduino Uno's okay, and Mega + Ethernet is not, writes "avrdude: stk500v2_ReceiveMessage (): timeout".

Try unplugging the Ethernet shield to make sure it's not interfering with the upload. It shouldn't because the Ethernet shield doesn't use the serial pins but I have seen occasional reports here of Ethernet shields causing uploads to fail.

pert:
Try unplugging the Ethernet shield to make sure it's not interfering with the upload. It shouldn't because the Ethernet shield doesn't use the serial pins but I have seen occasional reports here of Ethernet shields causing uploads to fail.

Then, the whole point of such a load is lost, probably easier to buy an extension cord YUSB.

I'm not saying you have to give up using the shield permanently. Just do a quick test. When you're troubleshooting you need to methodically rule out the possible causes of the issue. If the issue still occurs without the shield then you know it's not the cause. If the upload works without the shield then you will need to find out why the shield causes the upload to fail. Either way you're one step closer to getting it working.

I like to use the Ariadne bootloader to upload to my boards that are connected to Ethernet, that way I don't need to worry about getting them close enough to my computer for USB.