TGY 9X LCD gibberish

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Radian
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TGY 9X LCD gibberish

Post by Radian »

After putting up with the stock firmware for a couple of months, I recently flashed my stock TGY 9X with er9x and all was working well for a few days - then the LCD started to mess up.

I've searched over these forums and others and see the LCD is prone to some known problems. So I checked the connections between the processor and the LCD. All 5K1 and a 10K resistors are good so I put a scope on the data and control lines to check the waveforms. Now I don't know exactly what I should see - but while all 8 data lines (pins 44 to 51) pulse, only three out of five control lines have a switching signal. Pin 36 and 38 burst low for 600us while pin 40 bursts high. Pin 37 stays high all the time and pin 39 stays low all the time. I kind of expected to see all control lines waggling. Can anyone confirm if this is to be expected?

The LCD is more readable some times than others. At best it's streaks and missing areas, at worse it's barely visible at all. I was going to just get a replacement (following this link: http://openrcforums.com/wiki/index.php/ ... as_died%3F) but the R2 site link is dead there - and it looks like it's out of stock when I search around.

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MikeB
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Re: TGY 9X LCD gibberish

Post by MikeB »

The reset signal will stay high, just used once at start up, the write line stays low as we are always only writing.
The other 3 signals are chip select, control/data and strobe so should be changing.

The spare LCD does show up on this page:http://www.r2hobbies.com/catalogsearch/ ... ?p=3&q=lcd, although it also shows as "out of stock".

It does sound as though your LCD is failing.

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Re: TGY 9X LCD gibberish

Post by jhsa »

This has some very few chances of being the problem, but did you check if the LCD connector is well inserted and straight? I find it strange that the problem started shortly after flashing.

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Re: TGY 9X LCD gibberish

Post by Radian »

Thanks guys - but I've just had an interesting development: I decided to re-flash my stock 9X firmware backup as a last-ditch resort and to my surprise the display worked straight after it booted. I tried to re-load the backed-up eeprom but eepe complained that the .hex file was the wrong format (I don't understand eepe's various formats and uses for them). So it beeped non-stop but it looked like nothing was wrong with the LCD.

So I flashed the firmware with the same er9x image as before (http://er9x.googlecode.com/svn/trunk/er9x.hex) and it was still working OK afterwards. I've now restored the last eeprom settings I was using and so far so good. Mike, can you think of any way er9x could have got into a persistent state that caused a garbled LCD? I'm pretty certain that the hardware hasn't been the issue here. All the checks I did (re-seating the connectors, measuring voltages etc.) came up good. Things only turned around the instant I re-flashed the firmware.
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Re: TGY 9X LCD gibberish

Post by MikeB »

If the flashing didn't quite work right, for some unknown reason, then it could cause the problem you describe. A very small number of flash attempts, across 9X and Taranis, have resulted in something wrong that a re-flash has fixed.

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Re: TGY 9X LCD gibberish

Post by Radian »

I was just beginning to wonder about the 5V rail tolerance on the chip during programming, it's never been an issue wiith the PIC chips I usually work with but I'm not familiar with Atmel parts or their in-circuit programming. I will keep an eye on this from now on.

EDIT: I've started a new topic to consider using a boost convertor to improve the 5V supply when programming and using the transmitter when connected to USB:
viewtopic.php?f=25&t=6351
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Re: TGY 9X LCD gibberish

Post by MikeB »

The datasheet indicates 4.5V is the minimum guaranteed to work with a 16MHz crystal.

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Re: TGY 9X LCD gibberish

Post by Radian »

Rats. Before I've even fitted my boost circuit the display's gone again. I feel I ought to be re-flashing with the stock firmware to see if that exhibits the same problem but I can't update the eeprom. The .epee format I've been successfully loading and saving my er9x eeprom in look like xml i.e. start <!DOCTYPE ER9X_EEPROM_FILE> However, the stock firmware eeprom save I have is in bin/hex format and eepe complains that there's an error loading the file "File may be corrupted, old or from a different system." Yet I saved this image using eepe just before I flashed er9x. I didn't pay much attention to it though thinking I wouldn't need to look back. Rats.

I just re-flashed the eeprom for er9x and that didn't help. I then re-flashed the firmware (which seemed to instantly cure things yesterday) but it's still showing garbage. Any pointers on how to restore the full original so I can rule things in/out?
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Re: TGY 9X LCD gibberish

Post by MikeB »

Have you used the BURN menu in eepe? There is an option to "Write EEPROM memory from file". This should just write the EEPROM, from the file, without eepe looking to see if the file is valid for er9x.

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Re: TGY 9X LCD gibberish

Post by Bill »

Mmm the elephant in the room here is what happens if you disconnect the BASP from the tx circuit after programming maybe it is producing an unexpected current drain.
In my TX's I have left a connector for the programmer built in and removed the programmer after use,because I wanted to use the programmer on several other Atmel projects.
I have always programmed on the three and a bit volts setting with good results using the mySmart USB light.
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Re: TGY 9X LCD gibberish

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MikeB wrote:Have you used the BURN menu in eepe? There is an option to "Write EEPROM memory from file". This should just write the EEPROM, from the file, without eepe looking to see if the file is valid for er9x.

Mike.
Yes thank, the option to write eeprom from file was going through the motions without complaining but when it finished, the message EEPROM ERROR stayed up along with the beep. I could just about read it at the top of the LCD but it's all very streaky. I use the past tense because I began to suspect the .hex file so googled around for a stock image. What I found did flash OK so that's what was wrong. However, all I now have is a stock 9X with a streaky display :-(

I take it, from what you said about the R/W line, that the LCD has a controller of some sort on the glass? Maybe it was just a coincidence that the LCD temporarily recovered when I re-flashed it with the old firmware yesterday - I must have flashed it a dozen times today with original and er9x and it's still got a garbage display. Apart from that it all seems to work OK so I guess that's the end of that. Wasted a whole day making the booster too!

I liked er9x though so maybe I should get a 9XR and save messing around... is it possible to swap the 9X module into the 9XR so I can stage my expenditure!?

Unless, of course, someone has another suggestion to fault-find my 9X. I hate the idea that it's all working bar the LCD!
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Re: TGY 9X LCD gibberish

Post by Radian »

Bill wrote:Mmm the elephant in the room here is what happens if you disconnect the BASP from the tx circuit after programming maybe it is producing an unexpected current drain.
I've been doing that already Bill - I made it so I can unplug the USBasp inside the case while messing around. Doesn't make any difference I'm afraid.

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Re: TGY 9X LCD gibberish

Post by MikeB »

The LCD does indeed have a controller built in, together with charge pumps to generate the operating voltages. These voltages are developed on the row of capacitors just beside the LCD connector. It's worth having a close look at the soldering of these capacitors as a poor connection to even one of them could cause your problem. Maybe even lightly touch each connection with a soldering iron just to be sure they are OK.

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Re: TGY 9X LCD gibberish

Post by Radian »

Capacitor solder joints are all OK and I used a capacitance meter to check - all read around 0.7uF I think I've eliminated everything beyond the magic that takes place on the glass!
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Re: TGY 9X LCD gibberish

Post by Bill »

Sounds as though you should complain to hobbyking some people have got a new TX sent to them seems this problem is cropping up fairly frequently.
r2hobbies used to have a replacement lcd but that seems out of stock currently
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Re: TGY 9X LCD gibberish

Post by MikeB »

RC Tanks in Australia seem to have some: http://rctanksaustralia.com/shop/index. ... h=19_20_64.

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Re: TGY 9X LCD gibberish

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Re: TGY 9X LCD gibberish

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Currently about 1.83 Aus dollars to the pound, so just over £8 from RC Tanks.

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