Re: [uCsimm] cs8900 & wait-states

From: daniel haensse (daniel.haensse@fhk.usz.ch)
Date: Wed Dec 06 2000 - 09:52:13 EST


Am Mit, 06 Dez 2000 schrieben Sie:
> daniel haensse wrote:
> >
> > Hi
> >
> > in the file uCcs8900.c in function cs89x0_probe1 I have found
> >
> > *(volatile unsigned short *)0xfffff112 = 0x01e1; /* 128k, 2ws, FLASH, en */
> >
> > why do we use six wait-states to access the device?
> >
> > Dani
> > This message resent by the ucsimm@uclinux.com list server http://www.uClinux.com/
>
> You will have to use 1 wait state as the cs8900 has an access time of
> 135ns and the DragonBall (16mhz) has a 100ns access time for Data
> Valid. An additional wait state may have to be thrown in to allow for
> any additional signal settling, although the 163ns access time of the
> DragonBall @16mhz 1ws should be enough.
>
> TomW

yes, I agree, so this line in the uCcs8900.c must be
1ws:
*(volatile unsigned short *)0xfffff112 = 0x0191; /* 128k, 1ws, FLASH, en */
or 2ws:
*(volatile unsigned short *)0xfffff112 = 0x01a1; /* 128k, 2ws, FLASH, en */
this will increase the performance of the interface.
This message resent by the ucsimm@uclinux.com list server http://www.uClinux.com/



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