AW: [ECOS] how to measure time from within flash_program_buf

AW: [ECOS] how to measure time from within flash_program_buf

[Neundorf, Alexander]

Hi,

> Von: Andrew Lunn [mailto:andrew@lunn.ch]
> 
> On Tue, May 23, 2006 at 10:05:25AM +0100, David Vrabel wrote:
> > Neundorf, Alexander wrote:
> > > Hi,
> > > 
> > > in the Intel 28fxxx flash driver there is a timeout used, and this
> > > timeout is specified as a simple loop which is executed 5000000
> > > times. Now we have a fast processor and a slow flash, so 
> for us this
> > > timeout isn't big enough. We could simply increase the count, but
> > > this still depends on flash and processor speed.
> > 
> > I'd have suggested putting HAL_DELAY_US() macro calls in 
> the loop.  That
> > would give you a lower bound on the timeout.  However, I 
> think it it has
> > the same problem as HAL_CLOCK_READ() below.
> > 
> > How about sticking a few more functions (like hal_delay_us) 
> in .2ram ?
> 
> These functions are normally in the platform HAL, or varient HAL. So
> you would have to change every target. A lot of work...
> 
> Also, i work on a target which has a reasonable amount of flash and
> very little RAM. I don't want these functions in RAM because i don`t
> have space for them and my flash driver does not require them.

These are all the issues we also thought about but didn't come to a nice solution. 
While making the loop count a CDL value is better than hardcoding it, it is still not really good.

Bye
Alex

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Re: [ECOS] how to measure time from within flash_program_buf

[Andrew Lunn]

> These are all the issues we also thought about but didn't come to a
> nice solution.  While making the loop count a CDL value is better
> than hardcoding it, it is still not really good.

Implementing a time based solution is also not really good since it
adds bloat. 

99% of hardware will always run at the same speed and have the same
flash access speed. You only once need to calibrate the loop and then
it is fixed for the hardware. So there is no real need to dynamically
calibrate your delay loop.

          Andrew

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