2008-12-11 02:45:01     LCD Framebuffer with Nanox - how to know when memory is changed

2008-12-11 02:45:01     LCD Framebuffer with Nanox - how to know when memory is changed

Tony Clifton (BOUVET ISLAND)

Message: 66620   

I'm trying to implement a framebuffer driver to work with my custom LCD hardware. (GPIOs connected to LCD)

If I cat /dev/fb0 into a file, the image is as expected.  The Nano-x <--> Framebuffer interface therefore seems to be OK, but my driver's drawing functions don't seem to be called, and nothing is displayed on the LCD.

Should a timer be used to periodically update the framebuffer onto the LCD, or is there another way in which the framebuffer driver gets notified when changes occur.  Since functions like FillRect gets implemented in the framebuffer driver structure, I would have though there should be a mechanism that calls these functions, such as FillRect, CopyArea, when the framebuffer changes.

Am I missing something here?

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2008-12-11 02:53:41     Re: LCD Framebuffer with Nanox - how to know when memory is changed

Mike Frysinger (UNITED STATES)

Message: 66621   

there are a bunch of existing framebuffer drivers which are known to work fine which you can read ... just search the wiki

the LCD driver sets up a continuous DMA to PPI  on a specific piece of memory which contains the image

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2008-12-15 02:13:46     Re: LCD Framebuffer with Nanox - how to know when memory is changed

Tony Clifton (BOUVET ISLAND)

Message: 66703   

Thanks Mike,

How will the DMA to PPI work in a scenario where pages need to be set before a write etc.? 

In other words, my LCD device cannot be simply mapped to memory, but uses the ST7565 driver.

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2008-12-15 02:57:37     Re: LCD Framebuffer with Nanox - how to know when memory is changed

Mike Frysinger (UNITED STATES)

Message: 66704   

i really dont know what you'