CFAL160128B OLED Display Problem

[schilder]

I'm using a CFAL160128B OLED Display running with a AT91SAM7 Controller.
I use the example source for the avr and i adapted it to the AT91SAM7.
It's working but every time when the color changes to white my Controler resets always.
I use the example circuit with the LT3467 for the 15V power supply.When the controler resets the current is going up.
So i replace the LT3467 power supply with a seperate DC power supply but nothing changes.
Any idea??

Crystalfontz LCD Blog

Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.

 

[CF Tech]

I think you are on the right track, white uses the most current.

What does the logic supply on the processor (+3.3v, I assume) do?

Maybe write a slow loop that fills the screen over say 1 minute, and watch the +3.3v processor supply.

 

[schilder]

No results

I think you are on the right track, white uses the most current.

What does the logic supply on the processor (+3.3v, I assume) do?

Maybe write a slow loop that fills the screen over say 1 minute, and watch the +3.3v processor supply.

The 3.3v processor voltage is stable. The Oscilloscope doesn't show anything which could lead to problems.

I have attached the circuit and pcb may be you have any more helpful ideas.
The CPU is running without problems when i remove the display.
Displaying red,blue ore green also works but when displaying white the cpu resets.
Sometimes i can see some white pixels or lines without reseting.

 

[CF Tech]

It almost certainly has to be power supply issues.

It is very hard to see the type of power supply trouble that can cause these kind of problems. If the supply is to be 3.3v, you would want to set up your scope to trigger in single shot mode at say 3.2v and then start to draw your white. Hopefully the scope will trigger at the same time the display hangs. If you do not use single-shot mode, it will probably just look like a nice 3.3v line.

Your PCB looks generally nice, but you would want in the next revision to place the decoupling capacitors as close as possible to the display connector:

As voltages get lower and processors (even low power ones) get faster, the power supply and power distribution become very critical.

Also, the layout of the switcher is super critical. It could be that the switcher is pushing noise back onto the power supply, which is resetting the AVR or LCD controller.

Can you try disabling the switcher (remove L1/D1) and power the OLED from a bench supply?