Hi guys
Experiencing a strange issue with my 1.3" i2c oled and Nano.
The screen doesn't power up like it used to every time I power up the Nano, unless soon after power I connect my (unpowered) USBtinyISP to the ICSP header! :o
And stays on working fully until power is cycled again.
So:
Power up nano (via any power source be it usb or external 5v), screen black.
Connect USBtinyISP to ICSP, screen comes alive, flashes a few times but stabilises and runs fine.
Remove USBtinyISP, screen still on.
Hit reset buttom, screen still on.
Pull USB power, all goes off.
Apply USB power again, screen black again and you can repeat all steps again.
Sometimes (like in vid) connecting USBtinyASP does nothing, but then resetting brings display on.
Please watch video here: http://vid362.photobucket.com/albums/oo70/djivesp/Mobile%20Uploads/2015-03/VID_20150305_221128.mp4
It's a 4 pin display: VCC, GND, SDA, SCL.
Hooked up like this
Nano > OLED
5v > VCC
GND > GND
A5 > SCL
A4 > SDA
It does the same with the sample u8glib sketch, and same behaviour using all the different initiation config lines.
It also does the same on another Nano that's known to be working fine.
Isnt this weird!?!?
You realise when you find this it'll be one of those obvious things that just makes you shake your head 
Have you tried putting some pullup resistors on the SDA/SCL lines? (assuming that it is I2C, since on those chinese displays the 'labels' are guidance at best).
It might also be worth checking voltage levels (eg is that definitely a 5v display and not a 3v3).
I know - it's probably something totally dumb that I'm missing!
Annoyingly, it worked fine for a few months' worth of playing so I'm thinking the display or controller might be damaged. Maybe ESD or something. I ordered a few more, so in a few weeks I'll know for sure what's at fault.
You mention pullup resistors - I saw this in another project and was intrigued, i've not used pullups on i2c lines. I think it is i2c in this case, as they go from A4 and A5 which are sda and scl lines. I'll give it a go.
What sort of values would you use for these?
Tried 10k pullup resistors on SDA and SCL, and no dice. Still doing the same weird thing.
Hi
I have never read about such a strange behaviour, but in most cases, when i read about strange behaviours it often is related to a faulty breadboard. Try to solder your display with some wires to your Arduino Board.
Alternativly, try to use different parts of your breadboard. Maybe behaviour changes...
Oliver
good idea, olikraus.
I have another broadboard still in it's packaging, will try that and then soldering directly.
Hi guys,
So, it's not fully conclusive but I think the display was damaged.
Maybe ESD, maybe a VCC spike? Who knows. But since plugging a new one in, it just works.
I limited the VCC to 3.3v and added 10k pullup resistors on the i2c lines. We shall see how it works out.
Thanks for your responses.