When arduino starts up, RX TX lights doesn't blink. Only the PIN 13 and Green light turns on. Pin 13 light blinks thrice before getting stable. RX TX lights are not blinking at all. I am not able to upload any sketches. The error I get is "Not in sync resp=0x00" or "Programmer not responding" or "Not in sync resp=0x95" or "Not in sync resp=0x69" and so on. A new error everytime. Most probably the error is with serial communication.
A brief history of what I have done
I have a Relay which is operated at 12V. But Arduino works at 5V logic. So I used a comparator (IC741) to improve the logic (By setting Vcc and -Vcc at 12 and 0 and the input pins connected to arduino). I also connected HC-05 bluetooth module to use the relay using my cellphone. You know what I was trying was home automation. Also Arduino was connected to 12V DC supply (I think this was my mistake). Everything was going right.
Suddenly IC741 started burning,maybe I shorted some pins when I was trying to measure the voltages using multimeter. I quickly removed it. Suddenly HC 05 started burning. I immediately removed all the connections. After some time I turned on Arduino again (This time using USB connected to laptop). I connected HC05. The bluetooth module heats up again. I thought the module is now gone. I turned to check Arduino and as I stated I am unable to upload any more sketches. Most probably the bluetooth module cause an error in serial communication. May be not.
So my question is 1. What's the real problem. Is my bluetooth module gone? Or is Arduino gone? If arduino is still fine, how can I get the serial to work back and enable me to upload sketches? 2. If Arduino is gone, most probably the microcontroller Atmega328 is still fine. How can I use it now without Arduino (I don't have any extra Arduino)?
Things I have already tried :
- Loopback test : No echo back. Serial data can neither be sent nor received.
- When I open the Serial window, Arduino doesn't resets as it it earlier.
- RX TX Vin and 5V pin reads 4.99V. I hope they are fine.