Arduino Mega: Tx and Rx lights stuck

Hi,

I problably fry my FTDI chip last night. As you read on subject both Tx and Rx leds are stucked on.

Is there any way to certify that the FT232RL is defective? I do NOT have 3V3 (I believe that it is all I need to call the FTDI chip dead).

Can anyone tell me how to prevent that from happening? Not sure how I did it :(

Sorry for all those questions. Hope this thread will help someone in future.

Thanks.

Not getting 3.3V out is a good sign the FT232RL is dead.

One way to prevent it is to not short out the 3.3V output, or connect it to 5V, etc. It's a very "sensitive" output with no protection and doesn't take much to kill it.

Otherwise, it's kinda hard to kill the FT232RL unless you directly tap in to the Tx and Rx lines.

-- Check out our new shield: http://www.ruggedcircuits.com/html/gadget_shield.html

http://www.ftdichip.com/Support/Utilities.htm#FT_Prog Be careful with this tool - it can do a lot of harm...

Hi RuggedCircuits, I'll take extra care when handling my Arduino. Probably one of the situations you described happened and now the only solution I see is to replace FTDI chip.

What do you mean by "directly tap in to the Tx and Rx lines"? Can you elaborate a little bit more on that?

Hi deSilva, unfortunatelly I do not have USB connection to my chip. It is no longger recognized. Windows does not even detect the USB device. It is good to know the existency of such tool but I belive it will not help me right now. Please educate me if I'm wrong.

Thank you guys, Regards, Douglas

:'( Then there is no hope any more... Replacing the chip is not so easy...

What do you mean by “directly tap in to the Tx and Rx lines”? Can you elaborate a little bit more on that?

Digital pins D0 and D1 are connected to the FT232RL through 1k resistors. It is possible that if you apply >5V or <0V to these pins the FT232RL will be damaged if you sustain the voltage long enough (though the AVR will be damaged even earlier!) 5.5V should be fine, but 30V will probably not be. Also, there are 4 pins brought to an infrequently-used header (X3) which connect directly to the FT232. If you apply voltage and/or short these pins you will damage the FT232, whether intentionally or unintentionally by setting the Arduino on top of some clipped resistor leads :slight_smile:


Check out our new shield: http://www.ruggedcircuits.com/html/gadget_shield.html

Also, there are 4 pins brought to an infrequently-used header (X3) which connect directly to the FT232. If you apply voltage and/or short these pins you will damage the FT232, whether intentionally or unintentionally by setting the Arduino on top of some clipped resistor leads

That does make sense. Thank you one more time.