Blank Screen with FRskyLite mod

GTiDon · Post by **GTiDon** » Wed Mar 28, 2012 8:14 am

Hello

I have done the mod as in viewtopic.php?f=23&t=50

I also have the problem where the TX does not always startup and the screen remains blank.

Is there a solid solution for this problem? I have not added any resistors yet as I rather want to know the exact solution before guessing

yovio · Post by **yovio** » Wed Mar 28, 2012 11:25 am

Where do you solder the 5v from FrSkyLite? If you take it from the TX mainboard, it will be like this. Try solder the 5v connection to a regulator board where the buzzer is, look at one of the tutorial for Speaker and Heptic modification, the tutorial will shown where is the 5v solder point in the regulator board.

GTiDon · Post by **GTiDon** » Wed Mar 28, 2012 7:44 pm

I have moved the 5V to the board as mentioned above and still same problem.

I have also tried a 470 ohm resistor between pin 2 and FRskyLite.
and also tried two 1k resistors on both miso mosi with same random switch on problem

GTiDon · Post by **GTiDon** » Wed Mar 28, 2012 9:24 pm

Well I have now made the problem go away..

I added a 5k Ohm Resistor to the FRSky RX (Green Line)

I am still not comfortable with this, Is it safe? or should I add more resistance? As mentioned before up to 10k Ohm?

Hasse.69 · Post by **Hasse.69** » Wed Mar 28, 2012 9:32 pm

Very good picture.
Wiki?

Post by **jhsa** » Wed Mar 28, 2012 10:07 pm

Something doesn't look right on that picture.. where it says frsky rx and frsky tx shouldn't it say MOSI and MISO?? tx and rx are on the module side.. please can someone confirm what i'm saying here?

I've made the telemetry mod by Mike Blandford but instead of a level converter with the MAX IC I used the frsky upgrade lite which is basically the same.. I still put the resistors following Mike's schematic with the indicated values. and it works. I think I got power from the board's 5V. the frsky lite shouldn't cause any problems I think. It doesn't load the regulators as it takes nearly no current..
here is the link to Mike's mod.. I think I already post this before but I'm not sure..

http://er9x.googlecode.com/svn/trunk/do ... ryMods.pdf

João

GTiDon · Post by **GTiDon** » Thu Mar 29, 2012 3:56 pm

I dont understand his diagram. The problem with all the tutorials is that is shows the 2 switch resistors fine and then does not show the completed mod in a way that a non electronics expert can understand it

Post by **MikeB** » Thu Mar 29, 2012 4:32 pm

FIgure 4 shows the RED and White wires connecting to the processor. In Figure 3, these are on the top left going into the servo type connector, and two more wires from the right of the connector going to the convertor board. Figure 3 also shows mauve and orange wires connecting to the back board pins that go to the tx module. Figure 2 shows the inside of the module. These are the complete mods, so what is missing that you find does not show the complete mod? I can improve the description if I know what is needed.

If you have er9x now running, do you get the telemetry data on the screen?

@jhsa: The two pins are MOSI and MISO when programming, but are TXD and RXD (serial) when er9x is running.

Mike.

Post by **jhsa** » Thu Mar 29, 2012 10:23 pm

Got it.. just think that it's a bit more confusing.. I always had problems with those two little guys the tx and the rx.. never know what connects where

Clivew · Post by **Clivew** » Sat Jun 30, 2012 11:47 pm

Hi, I just got exactly the same problem with the frsylite module, the transmitter won't start
5 times out of 10. Unplugging it from the cpu fixes it, so I guess I need extra resistance on
the mosi line as well (have 470 ohms at present). I wonder what is causing this?

Clive

Post by **jhsa** » Sun Jul 01, 2012 8:21 am

can you post a picture of how you're connecting it, and where you're connecting it? please detailed info..

Clivew · Post by **Clivew** » Sun Jul 01, 2012 10:36 am

Here it is. 470 ohm resistors in the red heatshrink.
The telemetry works fine, once the transmitter boots!
Does the same thing with or without the DJT

Post by **jhsa** » Sun Jul 01, 2012 10:50 am

well, you have the frsky lite wired the other way round.. the bigger pins should go to the module.. these are the pins you would normally connect to the computer serial port (RS232)when upgrading the receivers ( that's what the frsky lite is for). And the frsky modules talk RS 232. please look at my picture..
Maybe that is your problem..

Clivew · Post by **Clivew** » Sun Jul 01, 2012 10:59 am

I did it like this: download/file.php?id=44&t=1

I did wonder if it was right, it's that Rob Thomson again!

Post by **Kilrah** » Sun Jul 01, 2012 11:05 am

Hmm that makes little sense indeed, AFAIK the "small" pins of the upgrade lite are the TTL level port, and the "big" pins are the RS232 signals. So the big pins should be the ones connected to the TX module, and the small ones to the CPU... With it backwards the CPU is receiving negative voltages.

Post by **jhsa** » Sun Jul 01, 2012 11:06 am

well, not so fast. swap it and test if your problem went away.. double, or better triple check your connections..

Post by **jhsa** » Sun Jul 01, 2012 11:08 am

And if that is the problem, which I think it might be, the wiki has to be changed..

Post by **jhsa** » Sun Jul 01, 2012 11:28 am

ATTENTION: On my picture I don't have the 2,7k resistor going to the module.. I'm using the DHT frsky module and if I need to programm this module I have to remove the connector going to the level converter anyway not causing damage to the radio. If you're using the DJT and that seems to be your case you must have that resistor in place.

João

Clivew · Post by **Clivew** » Sun Jul 01, 2012 1:03 pm

Ok, you were spot on with your diagnosis, jhsa, many thanks for that, it all works perfectly when
connected the right way round

I do have the resistor inside the DJT.

Post by **jhsa** » Sun Jul 01, 2012 1:09 pm

wonderful. congratulations. that means the mods using the frsky lite in the wiki should be corrected.. they are leading people in the wrong direction..
I'm happy that it's working and starting everytime

and that I was of some help..

tigar · Post by **tigar** » Sun Jul 01, 2012 1:11 pm

GTiDon wrote:
DHTMOD.jpg
Well I have now made the problem go away..

I added a 5k Ohm Resistor to the FRSky RX (Green Line)

I am still not comfortable with this, Is it safe? or should I add more resistance? As mentioned before up to 10k Ohm?

I have made the mod the same way ( the big pins of the lite module to the CPU mosi and miso) and I have the random startup problems. The radio and the telemetry works once it boots.
If I have it installed backwards should I change ASAP or with a 5k resistor I could skip the boot problems?
If there is a problem on this mod maybe the wiki should change?

Post by **jhsa** » Sun Jul 01, 2012 1:38 pm

I would do it, but that's my personal opinion..
The level converter is not wired right.. and now Clivew just proved that it was the cause of the problem..

Post by **Rob Thomson** » Sun Jul 01, 2012 4:22 pm

Who fancies updating the wiki?

Sent from my iPhone using Tapatalk

Post by **jhsa** » Sun Jul 01, 2012 5:00 pm

Rob, I wouldn't know what to do.. But the wiki should really be updated or people will continue to have the same problem...

Post by **Rob Thomson** » Sun Jul 01, 2012 5:03 pm

Always a good time to learn

If not... Send me full details of what to update and I will do it.

Sent from my iPhone using Tapatalk

Post by **jhsa** » Sun Jul 01, 2012 5:23 pm

well, it's just turn the frsky upgrade lite around basically. I think that was the only that wasn't right. best would be to edit the ones already there. also I use the DHT module and it seems that most of the people use the DJT module..
There are other tutorials that explain how to cut the traces on the back PCB. I don't have any photos of that. Best would be to merge all of this documentation. I could make a DOC/PDF of this part but would be better to put all this together in 1 tutorial so people would know exactly what to do instead of messing about with different ones and get confused like I did.
Is it possible to use pictures and text from other tutorials? then I could maybe try to put something together later. you would have to correct my lousy English though..

tigar · Post by **tigar** » Sun Jul 01, 2012 7:02 pm

I just reversed the lite module and the startup issues are gone!
Thanks for all the info on this thread...

Post by **jhsa** » Mon Jul 02, 2012 2:46 am

Ok, I've made (or at least I tried) a little guide. Here it is. Rob could you please check it and maybe put it in the wiki if you think it's ok?

Joao

P.S. - Sorry about my English

GTiDon · Post by **GTiDon** » Tue Jul 03, 2012 7:17 pm

Thanks Joao for your PDF and bringing my attention back to this thread, I have turned my frskylite around and removed all my extra resistors and tested working now..
Puzzles me how it actually did work the wrong way round? Ive been flying like that almost 4 months.

I understand these mods are do at own risk etc, but I think they should be tried and tested with the relevant hardware before wikid, It could have caused damage.. But luckily didnt

Post by **jhsa** » Tue Jul 03, 2012 10:13 pm

well, I've been flying mine like this for over an year now.. I guess is tested??..
I triple checked the PDF.. But you never know hehe.. And everybody puts disclaimers so why shouldn't I?

Anyway, glad you got it working properly.. What resistors do you say you removed?

Joäo

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