2008-07-28 06:56:14     LCD 640x480 for EzKit Blackfin 548

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2008-07-28 06:56:14     LCD 640x480 for EzKit Blackfin 548

Klaus Hachmeister (GERMANY)

Message: 59477   


Is it possible to connect a LCD 640x480 Pixel to the ExpansionPort of the Ez548-board?


Is there a framebuffer-device-driver for Blackfin-Linux available?




I think we need about 25 MHz for pixel-clock.


What do you about the performance of the Blackfin for user-applications when spending so much time for refreshing the display?






2008-07-28 07:11:09     Re: LCD 640x480 for Ez548

Mike Frysinger (UNITED STATES)

Message: 59479   


what expansion port are you talking about ?


there are a bunch of frame buffer drivers already written for different LCDs ... you can find them in the kernel, or search the documentation wiki


the core isnt doing the display refresh, the dma engine is ... the user application updates the framebuffer only when it needs to ... search the wiki for examples, or do the benchmarking yourself since the software to do so is all in the 2008R1 release for the bf548-ezkit




2008-07-28 07:32:56     Re: LCD 640x480 for Ez548

Klaus Hachmeister (GERMANY)

Message: 59482   


On the shematic page 12 of 17 (LCD) there is a note to set switch 17.2 and .3 to LCD24 or LCD18 "can be used on expansion interface .."


So i thougt there is a connector for an external display (other than onboard 480x272) available




I am looking for the Blackfin-device-driver like that one:




I think (hope) its easy to just change the timing-parameters, but maybe somebody else did it before.




Where can i find the driver you are talking about?






are a lot of M$-pPTs but no driver examples.




Thanks for the hint of the benchmarking-sw.


I know, the display-refresh is done by dma, but you need the same electrical bus to the memory like your applications.


So the DDR-interface will be busy for some time.


At 25MHz it will be three times so often used as with the original Ez548-display.






2008-07-28 07:38:47     Re: LCD 640x480 for Ez548

Wei Jiang (CHINA)

Message: 59484   


I attched a VGA LCD in bf561.


It should be well in bf548 as the DDR2 SDRAM has more high performance.




2008-07-28 07:41:00     Re: LCD 640x480 for Ez548

Mike Frysinger (UNITED STATES)

Message: 59485   


that is the driver that is used by the lcd on the bf548-ezkit ... all drivers get integrated into the kernel, they are not provided as separate downloads


we havent tried mucking around with the different interfaces to hook up other lcds since there is already one on there ... we prove out software and provide working examples so that other people can integrate their own devices


the front page of our website points to the documentation wiki: http://docs.blackfin.uclinux.org/




2008-07-30 06:26:43     Re: LCD 640x480 for EzKit Blackfin 548

Klaus Hachmeister (GERMANY)

Message: 59598   


Hello Mike,


creating a driver based on that one for the bf548-ezkit is no problem.




This driver uses


sclk= 131 MHz


eppi_cldiv is calculated to 7


This means


eppi_clk = 8.2 MHz






I need 25.175 MHz (typical)


So if i set eppi_clkdiv to 1 i set epp_clk to 32.8 MHz


Setting eppi_clkdiv to 2 sets epp_clk to 21.875 MHz






I need min. 23 MHz and max 28.33 MHz fpr my display.


How can i manage that ?












2008-07-30 06:56:00     Re: LCD 640x480 for EzKit Blackfin 548

Mike Frysinger (UNITED STATES)

Message: 59600   


then you can adjust your SCLK so that it can be divided down for your needs




2008-07-30 07:28:49     Re: LCD 640x480 for EzKit Blackfin 548

Michael Hennerich (GERMANY)

Message: 59602   


You want to run SCLK on the max and PPI_CLK as low as possible.


I saw quite some displays specified at 25MHz PIX CLK however you can run them with lower clocks as well.


The display might then look a bit pale.


25 and 21 should not make a big visible difference.






2008-08-13 09:03:00     Re: LCD 640x480 for EzKit Blackfin 548

Klaus Hachmeister (GERMANY)

Message: 60395   


@Michael: You are right.




I have just successfully connected a NEC 6448 display to my Ez548 board.


This is specified to use 21.0 MHz min and 29.0 MHz max.


I created a new driver based on the LQ043-driver.


(arch/blackfin/mach-bf548/boards/ezkit.c has also to be edited)


It works fine with clkdiv=2 (clk= 21.875MHz)


Adjusting SCLK or CCLK is not necessary.