Megadrum not recognized by the PC

[pit21]

Hello everyone!i have built megadrum but my Pc does not recognize it!I read some other posts and i disconected the ATmega32 from the board and it worked so i think it's a hardware problem.Can you help me to find what i have done wrong?any idea from where to start?

[dmitri]

I guess you have already read the advice - look for short circuits.

[pit21]

For the test i have nothing connected at the digital board!I have made my own pcb.I think its correct because if it wasn't orcad would show me errors!Anyway I have already looked for short circuits but either there is nothing either i haven't seen it.So can you give me some advise how to make my search for short circuits for effective?

I use only the usb to power the circuit.Is there any possibility that my usb port is can't give enough power how can i check it out and how could i fix it?

Thanks!

[dmitri]

Unsolder R18 from the Digital board. Put Atmega back in. Connect to the PC again. Still not recognised?

[dmitri]

And measure voltage between ground and Vcc while both Atmega and Pic are in the Digital board.

[pit21]

I tried the first way!i unsoldered R18(1K) which ends on the 17th pin of the PIC and left them unconnected but nothing happened.I measured the voltage and i got 4.89V.Is this enough?

[dmitri]

Break the trace coming from the pin 15 of Atmega. You will need repair this trace later. Still not recognised?

[pit21]

Alright!Now it is recognized but now no data is transfered between the two ICs.Just to inform you thise two pin of the Atmega(the TxD and the RxD)are have a bridge before they reach the.They are not dirctly conected by a track!
Here is a picture.

[dmitri]

I guess you don't have anything connected to the standard MIDI.
Restore the bridge to the pin 15.
Measure resistance between ground and the pin 15. What is it?
Measure resistance between Vcc and the pin 15. What is it?
Do you have Autoload config set to Yes? Change it to No and reconnect to the PC. Still not recognized?

[pit21]

Autoload config was off all the time.I measured the resistance as you told me.pin15 to the ground is about 65K and pin 15 to Vcc is about 56k

edit:i forgot!no!the midi interface is unconnected