TWR-K70 NAND and LCD Issues

[peterwoj]

I have a TWR-K70 board setup to use the NFC component in CodeWarrior for NAND access. I also have an LCD hooked up to the TWR using the LCDC component. Anytime I access the NAND I notice "static" random lines appearing on my LCD screen. I have tested this specifically by reading repeatedly from NAND into unused RAM on the TWR-K70 and every read accesses causes the lines to appear. Does anyone know of possible conflicts? Perhaps EMI?

[peterwoj · Accepted solution]

I resolved this problem by reducing the pixel clock for my LCDC component. This seemed to not be an issue with NAND access but instead DRAM on the TWR-K70 perhaps still a DMA timing issue I couldn't quite track down. The problem did not appear when accessing internal RAM regions only the external DRAM anytime a read or write occurred.

[marlinx]

Hi Peter,

I am also facing almost similar issue. by seeing your message i thought like i can get support from you.

i have a K70 Micro controller board which was designed in house. it has color LCD interface to it.

and i got the boards from my customer by saying there is a issue with LCD display. some of boards are working fine.

the issue i am facing is my LCD display is fuzzy on bootup and works normally after bootup.

I have no idea wat is causing flickering or fuzzy on bootup.

LCDCLK is configured to 12MHz clock

Please give suggestion to resolve this issue

[mjbcswitzerland]

Peter

I would take a look at the crossbar module since the NFC and LCD are both peripheral bus masters, whereby the NFC has higher priority by default. It is possible that the NFC operation is causing the LCD DMA operation to be blocked for a short time.

You could try setting a lower priority for the NFC or changing the polling strategy to round-robin so that each master peripheral gets a turn irrespective of the priorities.

Also memory-memory DMA transfers have higher priority and I tend to use round-robin otherwise long memory-memory bursts also affect USB operation (causing aborts and repetitions due to CRC errors resulting). Possibly due to the fact that I have round-robin as default strategy I didn't notice any LCD disturbances (to date).

Regards

Mark

http://www.utasker.com/kinetis.html

[peterwoj]

Mark,

I tried first setting the round robin policy for each slave module this did not seem to help. I then moved the LCDC periphals 0 and 1 to higher priority than the NFC module, still no luck. I'm using a different LCD screen than the TWR-LCD-RGB so I'll see if that is the cause. Thanks for the suggestions I was hoping that might be the trick.