after start up my L led flashes

HI i have just started with arduino
I am using an uno board and a windows seven pc

When i add a sketch to the arduino then remove power ie usb, then reapplie power the L led on the board (pin 13) flashes and does not perform the previously installed sketch? what is happening have i done somthing wrong ???
can anyone help me?
=(

You saw an "download complete" when you installed the sketch?

Post the new sketch using the # button above and a schematic of any hardware you have connected.

yes it says download compleate runs the sketch ok but then when i remove power and then re conect it doesn't work and the L led flashes sorry don't understand what u mean by "...using the # button above and a schematic..." i have removed all hardware from the arduino and it still performs this way?? Thanks

The pin13 LED does always flash on start-up. The '#' is button above (when composing) that adds code tags to your message so you can insert code snippets.

Double check that the sketch really isn't present (download the blink sketch, check that's working, download your sketch again, double check...)

Sounds like the 'sketch amnesia' bug in optiboot to me.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1295516707 (Old forum)

Hi i am now geting this error.
when i try to load the blink sketch
and i still dont know what u mean by the “#” button.

screen print.jpg

i can install one sketch and it works i then install the same sketch or another again and it comes up with the error and it still doesn't run the sketch after removing power

pluggy: Sounds like the 'sketch amnesia' bug in optiboot to me.

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1295516707 (Old forum)

if it is this the is there a way to fix it.

and i still dont know what u mean by the "#" button.

if it is this the is there a way to fix it.

Assuming this means what I think it means ("If it is this, is there a way to fix it ?")

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1295516707 (repeat of earlier link)

You read the first post and use the optifix.zip file linked there.

In a beautiful world, this would be the default bootloader on the Uno and not the half broken mess in the IDE.

hi i don’t have a second arduino to do this fix
??

pluggy:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1295516707 (repeat of earlier link)

i searched the error and found this http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1187909552;start=all they have the exact same problem but i can't figure out how to fix it i have manualy reset it ???

Hi new info
I brought another Uno to try and add a new bootloader to my bad one
I took the Atmel IC from the old board and installed it in the new board to see if the IC was bad
I discovered there was nothing wrong with Atmel IC but with the old board
I replaced the old IC in the old board and got the same problem as before
I was fiddling with the board and suddenly the sketch that was on the IC started i.e. blinking a led in pin 12.

Couldn’t figure out what I had done to fix this removed power and reapplied power and had the same problem

Spent a long time trying to find a bad connection on the board when suddenly it worked properly again I had touched the component directly beneath the USB port as depicted in the pic.

When I remove power I get the original problem but as soon as I touched the parts indicated by the arrows with my finger or screwdriver the sketch starts to run

does anyone have any ideas how i can fix this or what is happening
thanks

arduino uno.jpg

That's the 500ma polyfuse. It's designed to protect your PCs USB port from short circuits or drawing too much current and 500ma is the USB standards max current allowance. So what could be wrong?

  1. The polyfuse has bad solder joints to the board's pads. Try and resolder them and see if the problem goes away.

  2. The polyfuse is bad maybe has an internal crack, etc. It would need to be replaced if it's indeed defective.

  3. The polyfuse is fine but you have some component on the board that is causing a short circuit on the +5vdc bus. That might be hard to find which component or device is causing the problem, you only know that's it's not the 328 chip.

Lefty

hi thanks for you quick reply and you knowledge is there a way to test the fuse to see if it is broken eg with a multimeter

hi just found this could this be short you were sugesting

resistorold.jpg

resistornew.jpg

Hi fixed the problem i got a Stanley knife and separated the tracks
Thanks for your help I have appreciated it greatly I have been trying to fix this problem for two weeks
THANKS HEEPS
:slight_smile: :wink: :smiley:

toby-wan:
Hi fixed the problem i got a Stanley knife and separated the tracks
Thanks for your help I have appreciated it greatly I have been trying to fix this problem for two weeks
THANKS HEEPS
:slight_smile: :wink: :smiley:

Great troubleshooting, glad you got it working. And now you have a handy spare 328 chip as well. :wink:

Lefty