Raystar oled : Screen Issue - what I am doing wrong?

[SoundRider]

Hi Everybody,

I am a HAPPY new user of a PreenFM 2 since one week  . It's really a great little beast and I loved it from the first videos on the web.  Since I am not an expert building electronics, I ordered a pre-assembled unit ... very professional done IMHO ... no complaints so far.  OS is 2.03. I power my unit via USB (a simple converter plug from wall socket to USB socket and a standard USB cable, like for charging cellphones).

Now here is my issue with the screen. If I turn one of the encoders very fast - without using the "Instr" shortcut, the software seems to get a hick-up somehow and ...

either, the screen sweeps slowly from right to left or vice versa, the lines are somehow shifted ... 

or, the two lines, which are supposed to show the parameters (line 2 and 4) are missing ... 

During the screen issue, the rest of the unit seem to work propperly, including generating sound. A reboot is required to get to normal operation again.

So here is my question. What might be wrong? Maybe it's the powersupply? What is the minimum at volt/ampers required for an adequate power source?

Thanks for any advice in advance 

EDIT: My impression is that the chance to get an "display error" is highest, if I change the frequency of an operator during generating a sound.

[lokki]

i had similar issues with a macbook not delivering enough current to the preenfm2. try a different power supply (other usb port, different pc, wall wart instead of usb) and see if the error persists.

[SoundRider]

i had similar issues with a macbook not delivering enough current to the preenfm2. try a different power supply (other usb port, different pc, wall wart instead of usb) and see if the error persists.

Thanks for your reply. I will try this and report back.

[Xavier]

Hi,

I never saw this problem but heard about it.
It can be a display driver value that does not work anymore with the new OLED.

Could you let me know if it works better with the attached firmware ?

Xavier

[SoundRider]

Thank you very much Xavier,

downloaded the OS and will give it a try in the evening. Report follows

[SoundRider]

Sad, but the OS update didn't solve the "screen-error" ...

I create patches often supported by an external sequencer (midi) playing tunes or chords. It took about one hour today, until the error appeared, but then, moving an encoder, here it was again and this time lots of strange symbols srambled all over the screen. The sound was okay ... the little box played and played ...

Fortunately I have a workflow now to prevent total loss of my patch. Since every button is in function as it's supposed to be, I save a new raw patch out to it's destination and after having the screen error, I can use the menu button 5 times in blind flight, which saves the patch ... and reboot. Not perfect ... but not killing the fun at least 

[Xavier]

Yep, i expected the problem to be a timing one

Is your preenfm2 powered by USB ?
Have you tried different power sources ?

Xavier

[SoundRider]

I have used two different USB power sources now. Both are supposed to reacharge cell phones or tablets. One of them provides a special USB port to recharge iProducts and claims to provide higher current as usual. I havn't tested this port for very long now.

Fortunately the display crashes happen not every other minute. Yesterday I spend an hour with the Preen before it happened. After a reboot it did well for a longer time without any problems until I stopped using it.

The probability of the error seems to be linked to the complexity of the algorithm, how many voices I want to use, and if I have the sound playing along, when I turn the knobs quickly and use the shortcuts intensively to move between the menus.

[norbim1]

Hi,
in my f4discovery port i'm using Raystrar oled display, at first it had similar strange behavior and the probelm was that the oled was supplyed with 5V power while the driving data lines provides only about 3V high level due to the direct connection to the stm ports. The 3V is way below the datasheet specified input high level which is 0.9VDD (same as in Newhaven oled datasheet). My solution was to lower the 5V power to the oled by a diode, but i'm sure the resistor which was suggested in the oled noise eliminating topic can also be a good solution. Hope this helps.

Norbim

[lokki]

this is interesting. my screen problems when powering the preenfm2 from my macbook air vanished when i did the noise reduction mod. i installed an 68 ohm resistor, so the voltage drop is even more noticeable. i always thought the air did not have enough current for the preenfm2 but maybe the voltage was just slightly too high for the oled to get the digital signals right. it is a little over 5v when measured.

thanks for sharing

[SoundRider]

Thanks Norbim1 for sharing,

since I am not the electronic expert I will not open the box until there is no other solution around. But I will keep your info in my mind 

[lokki]

one last suggestion would be to power the preenfm from a wallwart via the 9v jack, not usb. that way the internal voltage regulator will generate the 5v and you may be in luck because the voltage level may be different enough to solve the hickups.

[SoundRider]

I think I will try this next ... there is no need to use USB power for me ... 

[Xavier]

in my f4discovery port i'm using Raystrar oled display, at first it had similar strange behavior and the probelm was that the oled was supplyed with 5V power while the driving data lines provides only about 3V high level due to the direct connection to the stm ports. The 3V is way below the datasheet specified input high level which is 0.9VDD (same as in Newhaven oled datasheet). My solution was to lower the 5V power to the oled by a diode, but i'm sure the resistor which was suggested in the oled noise eliminating topic can also be a good solution. Hope this helps.

Thanks a lot Norbim, that's very interesting 
Seems like i was lucky that the NewHeaven OLED worked fine

The 22ohm resistor lower the OLED VDD from 5V to 4.1V if i remember correcly, which makes 3.3v (data high output voltage) closer to 0.9VDD, which explains why the OLED mod fixes the problem.

SoundRider, i can mod  for free your preenfm2 if you want.
PM me if interested.

Xavier

[SoundRider]

...
The 22ohm resistor lower the OLED VDD from 5V to 4.1V if i remember correcly, which makes 3.3v (data high output voltage) closer to 0.9VDD, which explains why the OLED mod fixes the problem.

SoundRider, i can mod  for free your preenfm2 if you want.
PM me if interested.

Xavier

Xavier, thank you very much for your generous offer. I am interested.

But before I generate workload, I would like to ask, if Van Daal has provided this mod already? They state the following ... (from their web site)

"NEW: The Assembled PreenFm now contains a new custom made OLED screen shield for lower noisefloor."

In the formum community this seems to be a well known issue and seems to be soved. Is this related to the resistor?

Next question ... would using a 9V power DC adapter solve the problem? If yes, I would consider to go this way.

Last question ... is there information, how such a resistor has to be integrated? I have made some very basic soldering tasks myself and maybe it's basic enough to try a DIY. I only don't want to kill my little darling

I hope my questions are not too basic or stupid ... if ... then be merciful