industrialNETworX

Under special conditions the screen starts shaking and becoming unreadable, during a screen refresh.

This was noticed on images including Internet Explorer, while rendering an image. During the screen refresh the image starts shaking/flickering.

Reason for this behaviour is the internal DMA of the display controller may get interrupted by the ARM in special cases.

It only happens when the following two conditions apply:

• SDRAMs with a Write recovery time > 1 clk[/*:m]
• The ARM writes to SDRAM (with caches / write buffers enabled)[/*:m]

This Bug will be listed in the next netX500 Errata Sheet.

The only secure solution is to cut the time the ARM can contiguously access the Data Channel by setting the following registers:

------------------------------------------------
| Register Addr.  | Default Value |  New Value |
|-----------------+---------------+------------|
|0x00100180       | 0x00077777    | 0x00007777 |
|-----------------+---------------+------------|
|0x00100184       | 0x3FFFFFFF    | 0x1FFFFFFF |
------------------------------------------------ 

There is a small application attached to this topic, which can be integrated in your image. This can be done automatically at startup by adding it to the registry (see example below) or by starting it manually.

[HKEY_LOCAL_MACHINE\init]
  "Launch79"="DisplayFix.exe"

A demo EVC4 workspace can be downloaded here.

Note: There will be a small performance impact with this settings, as the display controller will be able to interrupt the ARM more often on the data channel. So be advised to only use the fix, if you have problems with your display presentation.

Regards

MT