2009-10-05 14:19:44     Synchronization problem with WVGA on BF537

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2009-10-05 14:19:44     Synchronization problem with WVGA on BF537

Larry Samuels (UNITED STATES)

Message: 80861   

 

I am using the BF537 on a custom board.

 

The board can drive a WQVGA display, 480 x 272, with some modifications to the lcd driver bf537-lq035.c

 

The external oscillator to the PPI clock is 12 MHz.

 

This works fine.

 

 

 

I am now trying to drive a WVGA display, 800 x 480, 16 bit RGB, 60 Hz refresh rate.

 

The external oscillator to the PPI clock is 33 MHz.

 

I have followed the timing diagrams of the LCD, and the synch signals appear correct.

 

I use the user/jpegview application to display a 800 x 480 image of a blue box with black background, but the image appears if there is no horizontal/vertical synchronization. Pixel data is not synchronized to the Vertical and Horizontal synch signals.

 

 

 

Is my problem PPI speed, Memory bandwidth, or something else?

 

How do I know if the BF537 is capable of driving this screen?

 

I can attach any files that would help analyze the problem.

 

My FAE contacted ADI and they thought it might be memory bandwidth.

 

 

 

Thank you for your help.

 

 

 

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2009-10-05 14:31:59     Synchronization problem with WVGA on BF537

Michael Hennerich (GERMANY)

Message: 80862    1) In you driver - request IRQ_PPI_ERROR

 

request_irq(info->irq, bfin_lq035q1_irq_error, IRQF_DISABLED,

DRIVER_NAME" PPI ERROR", info);

 

2) In the ISR print PPI_STATUS

 

static irqreturn_t bfin_lq035q1_irq_error(int irq, void *dev_id)

{

/*struct bfin_lq035q1fb_info *info = (struct bfin_lq035q1fb_info

*)dev_id;*/

 

u16 status = bfin_read_PPI_STATUS();

bfin_write_PPI_STATUS(-1);

 

printk("PPI_STATUS: = %x\n", status)

 

return IRQ_HANDLED;

}

 

3) In case you seeing PPI Underrun Erros it's likely a Memory Bandwidth

Problem.

 

-Michael

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2009-10-06 12:01:09     Re: Synchronization problem with WVGA on BF537

Larry Samuels (UNITED STATES)

Message: 80899   

 

Michael,

 

   Thank you for your response.

 

I added the irq to catch PPI errors as you suggested.  When I run the jpegview program, now I get PPI_STATUS = a00, 200 and 2a00 alternately.  This corresponds to Horizontal Tracking, Frame Tracking and FIFO Underrun errors.

 

I then commented out the enabling of the PPI Error IRQ.

 

I get less synchornization error when I increase SCLK from 100 to 133 MHz.

 

How fast can I make SCLK?  Is this dependent on my SDRAM or my Blackfin?

 

Any other suggestions would be appreciated.

 

 

 

Larry

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