openrcforums

Hey,

The ATMega64 pins on my 9x seems to be failing...
I have the following mods installed: FrSky Telemetry + Updated Buzzer

It has been working well for quire some time, until recently I started having problems with the FrSky Telemetry. The receiving part seems ot be working fine I get proper details
but the TX stopped working, I mean this because for example the part where the radio sends a message to receive the FrSky alarms levels stopped working. I see that as no data is
received.
A few days ago I notice the ElevatorDR switch stopped working as well.

Along with this I can no longer comunicate with the atmega... I've checked 4x already all the wiring, all comunications, basically everything I could think off.
So I'm assuming that it was the TX/MISO pin fault.
For the ElevatorDR swith part I even removed the SMD resistor and measure it and it is fine.

Any idea how to test the pins??? Asuuming that I can't load any new FW.

Hmm, strange problem..
For a start what telemetry mod have you done?
Try disconnecting the telemetry from the RF module and test if it still does the problem..
That is all I can think of at the moment..

Joao

Yes, which version of the telemetry mod have you done? Soldering and moving wires to alternate pins, or a telemetrez? How we ask you to proceed will depend on that. Also take some pictures of your board where you did these mods. Many times we have picked out a problem that you aren't seeing.
-Gohst

Thanks!
I've done the one that requires rewiring of the two pins.
I'll get a pic of the board.

All the frsky telemetry mods require the rewiring of the 2 pins
What we mean is did you use the level converter, or you did it without the level converter? which tutorial did you follow? values of the resistors used.. stuff like that
Picture (good resolution please) is also very important

João

Jhsa, the tez doesn't require any rewiring. It is solderless plug and play.
-Ghost

Sent from my LG-P999 using Tapatalk 2

Yeah but the TEZ is not a mod.. Is an addon..

Joao

These were the instructions I've used to do the mod:
http://openrcforums.com/wiki/index.php/ ... _Mod_FrSky
and
http://openrcforums.com/forum/viewtopic.php?f=23&t=430

So no level converter used.
This evening I'll take a high resolution pic of the main board.

Ok, I would suggest disconnecting the telemetry wires that come from the frsky module to the MISO and MOSI pads and see if gets better..

jhsa wrote:Ok, I would suggest disconnecting the telemetry wires that come from the frsky module to the MISO and MOSI pads and see if gets better..

My fault there as I forgot to mention it, I installed a plug in the wires that go out of the pads for those pins.
So I can easilly disconect it and that was my first test, I ended up actually unsodlering them and just leaving the cables that go to the ICSP plug with no luck...

Btw, I'm using a AVRISPMK2 programmer, I know it has some issues but I always was able to program using the -B option.
Eventually I tried with and without the 47uF cap on with no luck.

You say that your elevator DR switch also stopped working.. I think it is on pin 4, right?
Did you check if the resistor is good? also I would look for unsoldered pins on the atmega. It would not be the first and it wouldn't be the last

Joao

The avrisp mkii is a great programmer! When you try programming or reading the eeprom what error messages do you get?
-Gohst

@jhsa, yes that's correct. I ended up removing the resistor and measuring it outside to be sure it was ok. At it was fine. (220R) I checked continuity from the resistor to the pin.

@gohsthb, the common error when there is no response from the IC. (Something like: initialization failed, rc=-1)

I'll get a more details tonight.

It looks like it can't see the chip?

Here it is.

Look closely below the chip. There is something between the tracks from pins 3 and 4, in close up it is shiny. It looks to mee like a fault in the PCB manufacturing that could short these two pins together.
Try, using a very sharp knife, clearing this from between the tracks.

Mike.

You mean that tiny white dot between the tracks?
I think that was a speck of dust or some artefact from the photo but I'll give it a check.

Btw, the full output from AvrDude is the following:
----
Started AVRDUDE
/usr/local/bin/avrdude -c avrispmkII -p m64 -B 32 -P usb -U eeprom:r:/var/folders/g7/1trjj55d7wl0lc0_qjv0wmfw0000gp/T/temp.hex:i
=================================================================================

avrdude: stk500v2_command(): command failed
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to override
this check.


avrdude done. Thank you.


=================================================================================
AVRDUDE done - exit code 1
=================================================================================

----

Just to finalize this thread.
Continued testing and nothing... eventually decided to swap the uC.
As I was to change it I went to a AtMega128.

Just finished installing it and all seems fine, I can now program the uC normally and the ELEV switch that had stopped working is now working again.
So it really seems that some of the pins on the mega64 really stopped working.

As I have it now outside I'll do some tests with it to try and confirm this.

If you have swapped to the '128, you might like to check out this thread:
http://openrcforums.com/forum/viewtopic.php?f=95&t=3594

I would recommend fitting the 4 1K resistors even if you don't seem to have a problem, just to be sure.

Mike.

Thanks Mike.
I'll do that.

If I got it right is just cut the track and fit the resistors.
I have some SMD 0805 laying around I my use those.

Yes, I used the pictures posted by Flaps30 in that thread, cut the tracks where the red lines are and soldered some 0805 1K resistors across the cuts. You will (of course) need to clean some of the solder resist off for some of the resistors to fit. For those connecting to existing pads I removed the existing solder first, so the resistor fitted flat on the board, then re-soldered the pads and the resistor at the same time. For the other resistors I removed the solder resist, then I tinned the exposed copper to make it easier to solder the resistor to the track.

Mike.

IceWind wrote:If I got it right is just cut the track and fit the resistors.

Cut the tracks as per the red lines in the pictures on this post ----> http://openrcforums.com/forum/viewtopic ... =30#p52593

Thanks for the details.

Question, I assume the mega128 FW includes the changes for the pin re-routing of TRH and AIL switches right?
Since I loaded the mega128 FW those two are always on. I've re-checked the wiring but nothing.
As I see the FrSky telemetry menus I assume the firmware has also the needed pin changes...

Just saw the option "FrSky Mod Done"!

Have you re-rerouted the switches soldering them to the other pins of the CPU?
There is an option on the general settings (I think) to choose between a modded and anot modded board..

Yeap. found it right after posting the question.

Also added the 4x 1K resistor mod for the mega128 plus the backlight control mod.

All working now, all switches and I can read/write Flash & Eeprom.

Ok, now you only need a voice module, rotary encoder.. I assume you didn't you do the telemetry mod yet..


João

Telemetry mod was already done.
The rotary encoder I don't see much use for it, Instead I prefer to convert one pot to a second 3Pos switch.

Voices... I had also swapped the buzzer for another one but the result was not that good. Sound is low and didn't noticed much difference.
I'll see what's needed for the voices mod.