www.megadrum.info

Hello all,
I have one probelm. Last time I've tried to program my PIC18F14K50 with my COM cable on synthex 3.1 PCB.
Of course later I've found info, that with this series of PIC that's impossible, but before that I've tried to program it with WinPic soft. I've clicked on some checkboxes, and then by MD becomes unknown to computer via USB... What more - also I've lost midi in routing to midi out port. I was thinking that my optocoupler was also damaged, but I've changed it and it didn't helped. Right now I've lost possibility to update firmware of Atmega via MIDI. I've removed PIC from it's socket, put new opto and it also didn't helped. The rest is still working ok through midi out. So my question is, how MD behaves with PIC removed? It looses midi in? What I have to remove also with PIC to have my midi in back?
EDIT:
The midi on is not completely lost - when I connect keyboard, there are some midi messages routed, by they are totally different as they should be, eg. MSB or modulation instead of some note on, off...
BR
Michal

This doesn't sound good. The worst case scenario will have you not only replacing PIC, but ATMega too.

Yeah, it looks not good, but besides midi in, the rest is working very good. I can play with my pads with no other issues...
I will see what will happen when I will replace PIC, if it will not help, I will replace Atmega too.
BR
Michal

zaklinacz wrote:Yeah, it looks not good, but besides midi in, the rest is working very good. I can play with my pads with no other issues...
I will see what will happen when I will replace PIC, if it will not help, I will replace Atmega too.
BR
Michal

Dmitri will arrive shortly. I think he might have an idea on testing the chips.

Although unlikely, pin 14 on ATMega might have been damaged. It's the pin that's responsible for MIDI IN. Before anything else, check the trace leading to it for continuity and/or shorts.

Hi,
I've checked the continuity now and it is ok,
just for others: if you want to check this you have to check resistance between 6th pin of optocoupler and 14th pin of Atmega. It should be around 220 Ohms.
BR
Michal

The last time I checked it no software was able to program PIC18F13/14K50 using JDM type programmers. I managed to erase these MCUs but couldn't program them.
This is the reason why the official schematic still uses PIC18F2550 even though PIC18F13/14K50 are cheaper.
I use Pickit2 to program theses MCUs.

Dmitri,
but is there possibility that also Atmega is broken? with PIC removed I have no MIDI in working properly, I'm unable to update firmware, the MIDI thru is not working good - many errors... The activity LED is blinking during receiving sysex message...
How to check Atmega?
BR
Michal

1. Make sure that you have 4k7 between pins 6 and 8 of 6n138.
2. Make sure that the Atmega's crystal has correct frequency.
3. Make sure that you have 220Ohm between pin 6 of 6n138 and pin 14 of Atmega.
4. Make sure that the diode 1n4148 between pins 2 and 3 of 6n138 is not connected in reverse and is ok.
5. Make sure you don't have shorts around 6n138.
6. Make sure you don't have a short between pin 14 of Atmega and anything else.

If everything above is ok then your Atmega may have developed a fault on pin 14.

Everything, what you mentioned about, is ok - my MD was working properly. All problem with MIDI in started with my faulty programming of PIC. MD is still working ok, but without proper work of MIDI In port.
BR
Michal

Then I can only presume that pin 14 of Atmega is faulty.