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Topic: bug with serial port? (Read 3 times) previous topic - next topic


I think you may have gotten a Diecimila that was accidently burned with the wrong bootloader (the NG one).  The Dieicmila resets when you open a serial connection to it, however, the new bootloader quickly times out and starts your sketch, even with no delay in Processing.  I should probably add in code to include the delay, but commented out, so that other people with these boards with the wrong bootloader can uncomment those lines to get the example to work.  You might also want to burn the correct bootloader onto your board.  For example, uC Hobby has instructions for doing so with a parallel programmer: http://www.uchobby.com/index.php/2007/09/12/how-to-update-the-arduino/, or you can use an AVRISP mkII and the burn bootloader command in the Arduino environment.


Hi, I am not sure how to burn an up to date bootloader with the environment. Where would I find the latest bootloader and instructions on how to do that? is there any way to check to see if I do indeed have the NG bootloader by accident?

thanks for your help! I love the arduino and the way that you can simply interface to it.


I just realized that the solution you suggested would involve me getting a parallel or other programmer for the chip. Unfortunately i can't afford that. Could I return the board and have your distributor (MAKE magazine store) replace it with one with the correct bootloader?


There is a difference in the Diecimila, in that opening a serial connection to the board will reset it.

When doing a "tail -f /dev/ttyUSB0" the first time after connecting the diecimila to the computer, it will reset and its program will run from the start; breaking out of tail (ctrl-c) and restarting it will not do that (inbetween readings are lost though). I am just too lazy right now to check what happens when the computer is rebooted while the diecimila grafts.

PS: stty reports that HUPCL is set to off on the port. Trying above procedure with the arduino-IDE serial monitor will perform the reset all of the time.


Interesting.  hungerbug, are you on a Mac?  Did you unset HUPCL explicitly with stty?  Does the board rest if you connect to it with Processing?  I'd love to find a good way for people to prevent the board from resetting every time the port is opened.

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