DIGI FX board troubleshooting

Hi guys !

Well my digiFX shruthi used to work fine 2 months ago…but today it decided it wouldn’t…Here is the situation:

  • Control board powered fine
  • filter set on DSP
  • midi note message fine (i.e. midi is getting into the shruthi and the shruthi tells me so)

No sound at the output…None of the LED on the filter board are ligthen. Could that be the Atmega 328p having something wrong ? How can I check that ? Of course, this happens when I have to work for a gig schedulded in two weeks…



Hi Tom,

When things stop working suddenly it’s probably a bad solder joint… Try reheating all solder joints on the board! Check that the ATmega328p hasn’t popped out of its socket too…

Ok, let’s try to reheat all solder joints then. !

Reheated all the joint of the digiFX filter board…still no led lighten…

Coul a shortcut, due to manipulation, have fried the 328p ?

Are you sure your power adapter is ok?

It has worked for 1 year and a half with no problem…let’s check with another one…No change…

What’s bothering me is that none of the 2 leds are lighten…

What could be the reason no led are lightened (especially the red one)? I’ll have a scope tomorrow, what should I see when checking the 328p pins ?

How can I check my 328P is fried or not ?



No LEDs are lighted because the 328p doesn’t receive any signal. This means that either:

  • There’s a bad connection between the two boards.
  • The bandwidth limiting filter at the input of the 328p ADC is not working correctly.
  • The ADC peripheral on the 328p is damaged, or the ADC input pin is badly soldered.
  • The 328p does not boot because there’s something wrong with the quartz/caps around it (bad solder point)…

Random failure of electronic parts is very rare. Much much much rarer than failures in solder joints.

Due to the way it was built, there could have been a short between 2 of the 8 pins connecting the two boards.

  • Theres continuity between the two boards on all the 8 connecting pins
  • I reheated and added some solder on all joints of the filter board (this includes the 328p’s quartz)

That’s why I was thinking at a possible fried 328p.

Is there a way with the AVR programmer, to check if the 328p is working correctly ?

Try flashing it… if the AVR programmer can’t communicate with the chip, there’s something wrong.

Ok thanks, I’ll try this then !

Ok, when trying to flash the 328p with my avrisp mkII using the make -f dsp/makefile bake, I get this error:

echo “sck 10\
” | /usr/bin/avrdude -V -p m328p -C /etc/avrdude.conf -c avrispmkII -P usb -e -tuF

avrdude: stk500v2_command(): command failed
avrdude: stk500v2_command(): unknown status 0xc9
avrdude: stk500v2_program_enable(): cannot get connection status
avrdude: initialization failed, rc=-1
avrdude: AVR device initialized and ready to accept instructions
avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.
avrdude: Expected signature for ATMEGA328P is 1E 95 0F
avrdude> sck 10
>>> sck 10
avrdude> quit
>>> quit

avrdude done. Thank you.

make: ***** [bake] Erreur 1

What am I doing wrong ?



Using avrdude -V -p m644 -C /etc/avrdude.conf -c avrispmkII -P usb -B 10 for checking the m644 chips of other shruthis let me think my 328p is dead as it doesn’t respond (with the exact same programmer setup) to the command avrdude -V -p m328p -C /etc/avrdude.conf -c avrispmkII -P usb -B 10…

If the chip doesn’t respond, does it mean it’s dead, or could it be a problem with the bootloader ?

What could be the reason there is no communication between the ISP pins and the atmega even if conitnuity if fine between those ISP pins and the atmega ?

I tried to talk to my arduino UNO with the programmer, it’s fine, when I place the arduino’s chip on the digiFX board, I can’t get any information.

If I put my shruthi’s 328p on my arduino board, I can get “talk” with it using the programmer…

This is driving me crazy…

You should be able to program the 328 from the arduino with the programmer on the digi/fx board. If that’s not working and the digifx 328 is working on the arduino board the MCU’s are ok.
Do you see the light turn green on the programmer when you connect it to the board?

Yep, the programmer led turns green when connected to the isp pins of the digifx board…something else us going wrong on the board.

Could a faulty quartz prevent the programmer to talk to the 328

Did you check if the 328 is getting 5V at pin 7 and pin 20? And pin 8 and 22 are connected to ground?

Faulty quartz would probably give problems but since it used to work i would be surprised it’s broken now.

Faulty quartz does not cause a problem - a blank chip is configured to run on the internal oscillator anyway. Check that there are no shorts between some of the pins of the ISP programmer. Check that the chip gets power.

Ok, i’ll try this when coming back home

Hi all !

Well, no shorts between the isp pins, and 4,97V when checking VCC on pin 7 of the 328p…

What could be wrong then ?