Re: tHigh tLow discussion (was [pacth] I2C bug fixes for L-O and L-Z)

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On Mon, Feb 23, 2009 at 8:10 PM,  <ext-Eero.Nurkkala@xxxxxxxxx> wrote:
>> I am not entirely sure about the basis of Eero's equation:
>>
>> scll = (scl+3) * iclk
>> sclh = (scl+9) * iclk
>
> No, no:
>
> Exactly the opposite,
> +                       fsscll = internal_clk / (dev->speed * 2) - 3;
> +                       fssclh = internal_clk / (dev->speed * 2) - 9;
>
> means a longer period for scll. (and shorter for sclh)
Oops.. copy-paste typo.. :(
tLow = (scll+3) * iclk
tHigh = (sclh+9) * iclk
Vs:
TRM:
tHigh  = ( sclh +5 )*iclk period
tLow  = ( scll +7 )*iclk period

But my question is this: why are we trying to a different equation
here compared to the equation in the TRM? if the reason is that the
tLow and tHigh should be a variant based on board, probably
precomputed values or run time computed values wont work for all
platforms. the board file probably should give it as a platform
specific data. if this is not provided, use the run time computation..

just a thought..

Regards,
Nishanth Menon
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