FTDI programming and serial help

Hi,
Here is my situation. I have 2 arduino pro minis.

1st

  • has header pins installed
  • can use FTDI Serial to usb and I can see the output in the serial monitor.
  • when I try to upload a new sketch to the pro It just hangs and I don't get any response back.

2nd

  • has no header pins installed
  • can use FTDI Serial to usb and I can see the output in the serial monitor.
  • Uploads new sketch just fine.

Can anyone think of anything that would cause it not to work on just one of the boards?

Thanks

I just reburned the bootloader and it worked.

That is good you solved it and thanks for letting us know. I was thinking that if the wiring was the same between bad board and good board, the bootloader is something that could cause the problem. But you posted news of your fix before I had a chance.

There are a few ways to produce that symptom (upload fails, but sketch is running, and reburn bootloader fixes it):

  • Auto reset isnt working
  • Using one of the old bootloaders (ie, not bootloading/uploading to them as unos) and you uploaded code that uses the WDT
  • Fuses were set wrong (Once I saw a clone that didn't have BOOTRST set)