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Re: BUSCLK



    It seems I must use the main clock ( 20 MHZ )  for the LCD driver. The
chip is capable of using 100 MHZ clock ( epson s1d13706 ). I wanted to use a
clock signal from MCM. The reasons are
1- I could not find a 100 MHZ ( over 25 MHZ ) crystal around. Anyway I dont
know, how I can use a 100 MHZ crystal. The chip has no crsytal inputs. Do
you think the clock generator in the reference design works ? I'm not sure.
As a result, I think I must use a PLL to obtain higher frequencies. It is a
hard way.
2- I can use the 20 MHZ main clock but it would be ineffective. Why should I
use 20 mhz, if I could use 100 MHZ ? :( But I can't. I want to drive 320 RGB
240 LCD ( @xxxxxxx. May be ( very low probability ) 20
MHZ is not enough. I have not evaluated yet.
3- I dont want MCM to wait for the LCD controller. If I use 20 MHz clock, I
must use ( may be 5) wait states.

    The last solution was using 20 MHz main clock. Now we are there. :)

Martin

----- Original Message ----- 
From: "Mikael Starvik" <mikael.starvik@xxxxxxx.com>
To: "'Martin Fake'" <martinfake_76@xxxxxxx.com>; "dev-etrax"
<dev-etrax@xxxxxxx.com>
Sent: Monday, August 23, 2004 11:43 AM
Subject: RE: BUSCLK


Colud be possible but probably not a good idea. May interfer with SDRAM
operation. I amo not sure but I don't think the SDRAM clock is synhronous
with other bus signals. Why can't you just mount an external oscialltor?
How big is the LCD screen? What are the requirements on the communication
protocol?

-----Original Message-----
From: owner-dev-etrax@xxxxxxx.com">mailto:owner-dev-etrax@xxxxxxx.com] On Behalf
Of Martin Fake
Sent: Monday, August 23, 2004 10:12 AM
To: dev-etrax
Subject: Re: BUSCLK


    Hello again,
        Can I use SDRAMCLK for this purpose ? I suppose it is a 100 MHz
clock signal for SDRAM devices but I think it is possible to use it for LCD
controller :)  What do you think about it ?.

----- Original Message ----- 
From: "Mikael Starvik" <mikael.starvik@xxxxxxx.com>
To: "'Martin Fake'" <martinfake_76@xxxxxxx.com>; "dev-etrax"
<dev-etrax@xxxxxxx.com>
Sent: Monday, August 23, 2004 9:58 AM
Subject: RE: BUSCLK


BUSCLK is not intended to clock peripherals. If you need a clock for
e.g. a FPGA you should clock it separately and use handshaking or
similar between the CPU and the FPGA. For simple peripherals
it is enough to get a chip select and a read/write strobe.

Regards
/Mikael

-----Original Message-----
From: owner-dev-etrax@xxxxxxx.com">mailto:owner-dev-etrax@xxxxxxx.com] On Behalf
Of Martin Fake
Sent: Sunday, August 22, 2004 2:10 PM
To: dev-etrax
Subject: BUSCLK


     Hello,
         I need a clock signal for peripherals. I have seen a BUSCLK (C15)
pin in BUS signals group. But I have not found enough information about this
pin. Is it a clock output for peripherals or for only test signal ?

Martin