FAQ: LCD flickers while accessing SMSC lan 9220.(2011-03-23)

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2011-03-23 08:21:24     LCD flickers while accessing SMSC lan 9220.

Mahalakshmi M (INDIA)

Message: 99165   

 

Hi,

 

I am working with BF533 based custom board.

distribution 2009R1-RC1. We had Lan 9220 smsc chip interfaced to the BF533 via Async memory.

 

We see that when ever there is a ethernet access. LCD display flickers. Actually whle running the LCD in background we are accessing the ethernet. We also observed that the flickering varies with the ethernet data download size i.e, if size increases flickering increases.

 

ping 172.16.6.173 -s 100 ---> No flicker is observed

 

ping 172.16.6.173 -s 1000 --> Flicker is observed rarely

 

ping 172.16.6.173 -s 10000 --> Flickering Always

 

 

The priority for the LCD PPI is higher than the ethernet driver.

 

This flickering is not observed in smsc 9215.

 

Please help to solve this problem.

 

Thank you.

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2011-03-23 11:09:07     Re: LCD flickers while accessing SMSC lan 9220.

Mike Frysinger (UNITED STATES)

Message: 99167   

 

what do you  have CONFIG_BFIN_INS_LOWOVERHEAD set to ?

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2011-03-24 05:30:40     Re: LCD flickers while accessing SMSC lan 9220.

Mahalakshmi M (INDIA)

Message: 99213   

 

CONFIG_BFIN_INS_LOWOVERHEAD is set to 1.

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2011-03-25 02:15:52     Re: LCD flickers while accessing SMSC lan 9220.

Aaron Wu (CHINA)

Message: 99224   

 

What's your display paramter? Like the x-resolution, y-resolution and display refresh rate?

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2011-03-25 03:04:08     Re: LCD flickers while accessing SMSC lan 9220.

Mahalakshmi M (INDIA)

Message: 99225   

 

x-resolution = 320

 

y-resolution = 240

 

display refresh rate = 60

 

This flickering is not observed in smsc 9215.

 

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2011-03-25 03:36:57     Re: LCD flickers while accessing SMSC lan 9220.

Aaron Wu (CHINA)

Message: 99252   

 

Thanks for your information.

 

So looks like it's not a system bandwidth issue? To double confirm this you may try to lower the refresh rate for the display to a much lower value, displaying to static image to see if the flickering persists.

 

Also suppose there are not much difference between Lan 9220 and 9215, from the driver, did you do anything special for the lan 9220 when comparing to the 9215? For this, you may also consult SMSC, they are likey to help you more.

 

Then come to the electrical Interference, did you get two different PCB layout versions of boards, one mount 9220 and other mount 9215, or two boards of the same layout, one mount 9215 and other for 9220?

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2011-03-25 06:00:13     Re: LCD flickers while accessing SMSC lan 9220.

Mahalakshmi M (INDIA)

Message: 99254   

 

Do u mean there may be a chance if any interference of Ethernet signals causes problem of LCD display flickering .

 

Please Suggest.

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2011-03-25 06:46:54     Re: LCD flickers while accessing SMSC lan 9220.

Aaron Wu (CHINA)

Message: 99255   

 

Have given some suggestions in the last post, please have a try and check if it make sense for your case. There is a possibility  that the signal interference between Eth module and LCD module, that's why I asked you for information about the layout version. 

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2011-03-25 13:28:38     Re: LCD flickers while accessing SMSC lan 9220.

Mike Frysinger (UNITED STATES)

Message: 99259   

 

so try disabling it instead

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2011-03-29 01:27:07     Re: LCD flickers while accessing SMSC lan 9220.

Mahalakshmi M (INDIA)

Message: 99389   

 

Thanks for the information. have intimated our hardware team to check . Will update the status soon.

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2011-04-05 07:20:25     Re: LCD flickers while accessing SMSC lan 9220.

Isi Petruck (GERMANY)

Message: 99595   

 

Did you manage to solve the problem ? I am really interested, as I am facing the same problem !

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2011-04-05 07:35:29     Re: LCD flickers while accessing SMSC lan 9220.

Isi Petruck (GERMANY)

Message: 99596   

 

Before I forget,

 

It seems that the flickering only appears when data is downloaded to the blackfin, not while uploading

 

I tried tftp transfer from and to the board. Only when I download from tftp to the board the display starts flickering. When I upload a file to a local tftp-server there is no flickering visible

 

maybe this could be a hint

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2011-04-08 06:49:20     Re: LCD flickers while accessing SMSC lan 9220.

Aaron Wu (CHINA)

Message: 99693   

 

Do you involve DMA for your smsc9220 transfer? If so you may check your DMA channel priority setting. By default the PPI always has the highest priority for bf533.  Another point to check is to make sure the "DMA has priority over core for ext.acesses" is selected for kernel Blackfin Processor options, in case you are using non-DMA transfer.

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2011-04-11 05:47:14     Re: LCD flickers while accessing SMSC lan 9220.

Mahalakshmi M (INDIA)

Message: 99748   

 

Thanks Aaron

We are using Non-DMA trasfer for SMSC9220. Also DMA has priority over core option is also already selected.

 

Even though we are facing the issue.

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