2011-02-11 17:46:45     fbdev, lcd and spi

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2011-02-11 17:46:45     fbdev, lcd and spi

Carl Berglund (SWEDEN)

Message: 98098   

 

Hi, I have a Displaytech SDT033TFT LCD  that is connected to a BF537 STAMP board. For now it is only connected via the SPI bus.

 

I have browsed some code for existing LCD drivers, but these only used the PPI interface and RGB mode on the LCD.

 

As a frist step I only want to map some memory to a device in user space and when i write to it the driver uses this information and translates to SPI signaling to the LCD.

 

So here are a few questions I have:

 

1. Do I need a write function in my fbdev if I want to do this or can i use fb_imageblit, how does it work?

 

2. Can I have both SPI and PPI interface in the same driver, like SPI for changing static icons and PPI for streaming video?

 

3. How is the image transfered to the LCD in RGB mode?

 

4. What interface does SDL use?

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2011-02-11 17:55:26     Re: fbdev, lcd and spi

Mike Frysinger (UNITED STATES)

Message: 98099   

 

does the LCD have memory on it or something so that it doesnt need to constantly be refreshed ?

 

SDL doesnt care how screens are connected.  it only cares that you expose it as a framebuffer device.

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2011-02-12 05:39:39     Re: fbdev, lcd and spi

Carl Berglund (SWEDEN)

Message: 98112   

 

The LCD controller chip (D51E5TA7601) has an integrated DDRAM.

 

Okey, but how does SDL write to the fbdev, is it with open and write calls?

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2011-02-12 14:22:00     Re: fbdev, lcd and spi

Mike Frysinger (UNITED STATES)

Message: 98116   

 

you'd have to read the SDL code, but i dont think it matters.  you should be supporting the FB API in the kernel and then how the userspace app uses things is no longer relevant.

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