Does the board work if just plugged into USB with no other external power or other things attached to it?If not you must have damaged the board somehow when you applied the external +5vdc to the 5V pin. If you have a multimeter you might try measuring the voltage at the 5V pin to see what it reads when just attached to to the USB.Lefty
outcoming electronic component with 20 legs, which is called "ATMEGA328P-PU DIP-20 Microcontroller"
The 7805 of the Arduino...
... gives me the same Voltage, on the middle leg I get 4.3V and on the left leg I get 3.8V.
The 5V output gives me 4.3V which is OK.
Quoteoutcoming electronic component with 20 legs, which is called "ATMEGA328P-PU DIP-20 Microcontroller"the 328p-pu has 28 legs. count em...QuoteThe 7805 of the Arduino... a 7805 is not a standard part for the Uno, your wiring is not very clear in your description. Are you referring to the arduino's on-board regulator or an external component? If the onboard regulator, then it is irrelevant because you are powering the uno from USB. The v. reg. and USB are two seperate power sources. The middle leg (pin #2) of a 78xx is ground (0v), the left leg (pin#1) is input ( you never mentioned what the voltage is of your external power source you are using), and the right leg (pin #3) is output (5v). If this statement- Quote... gives me the same Voltage, on the middle leg I get 4.3V and on the left leg I get 3.8V.- is true, then something is either wrong with how you measured it or the 7805 is damaged or incorrectly wired.Wiring and description aside, you might try a loop back test (http://arduino.cc/forum/index.php/topic,73748.0.html) to see if the usb-to-serial chip is damaged.
Quote from: KobiSexy on Dec 06, 2012, 08:13 pmThe 5V output gives me 4.3V which is OK.Says who?It should be 5V ... 4.3V is a huge error and indicates the power circuitry is probably blown.
Just a shot in the dark, but I had a problem even getting my Mega R3 board to work withthe Arduino IDE in the first place. I couldn't find any info anywheres at all about this, except on the following thread, which gave a procedure that allowed me to install the proper driver for the R3 USB chip. Non-intuitive. Maybe you have the same problem.http://arduino.cc/forum/index.php/topic,133030.0.html
I connected 5V from 7805 to the 5V on the Arduino
QuoteI connected 5V from 7805 to the 5V on the ArduinoWhy would you do this? The Arduino has it's own 5V v.reg. First off, I would disconnect anything connected to the Arduino headers. Then if you're stillmeasuring only 4.3V on the 5V rail, with either USB or power to the Power Jack [assumingyou have an adequate external supply], it sounds like you have damaged the v.reg, or lesslikely some other parts on the board. Short of knowing how to go through and troubleshootevery part, sounds like time to buy a new one. [we all do it].
I tried doing it but unfortunately my computer doesn't recognize the Arduino...
I've been doing electronics for many years, but trying to troubleshoot a board with a bunch of tiny tiny surface mount devices is probably more trouble thanI'd like to go through myself [for a $30 board].
Power the arduino (just the arduino, remove everything else that might be plugged into it) by connecting an external source(7-12v) to the barrel jack. Does it turn on? If it does, what is the voltage at the 5v pin? QuoteI tried doing it but unfortunately my computer doesn't recognize the Arduino...make sure you have the right drivers installed. You may even try reinstalling the IDE software all-together. If that doesn't work, look into DFU mode for the USB chip. You might try simply resetting it before re-uploading the firmware.
Did you install the driver for it on the computer to recognize the arduino?
I turn the board on by connecting into Vin input 5V fron 7805 from another board.
5V from 7805 from another board to 5V input
Do you have any idea fixing it?
QuoteI turn the board on by connecting into Vin input 5V fron 7805 from another board.This does nothing for trying to see if the onboard regulator is functional, and does not answer my questions: (#1)what is the voltage at the 5v pin? 4.2vNow, if you do not have a 2.1mm plug that's a different issue, but (#2) what are you powering the 7805 with? 12v ADAPTER and (#3) what is the measured voltage output of the 7805? 5vQuote5V from 7805 from another board to 5V inputIf everything is connected properly and operating normally, this shouldn't have caused a problem. You can feed 5v (from a well-regulated source) directly to the 5volt rail, I do it all the time. QuoteDo you have any idea fixing it?Google does... "Arduino DFU mode"
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