Michael Rigby-Jones wrote:

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>>-----Original Message-----
>>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>>Sent: 01 September 2005 15:01
>>To: Microcontroller discussion list - Public.
>>Subject: Re: [PIC]: what does bit SSPSTAT<7> do ?
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>>but how does it control the slew-rate:
>>PIC16F877 manual states
>>0 = slew rate control enabled for high speed mode (400 kHz)
>>1 = slew rate contral disabled for standard speed mode (100 
>>kHz and 1 MHz)
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>>what is enabling of slew rate ???
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>>I guess they mean something like this:
>> 0 = smitt-trigger input enabled (for any frequency you like)
>> 1 = smitt-trigger input disabled (for any frequency you 
>>like) and above it doesn't do anything with the slew rate of 
>>the output.
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>>Is this correct ??
>>
>>Stef Mientki
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>Slew rate refers to the maximum rate of change of voltage (which essential determines the rise/fall time of the clock/data signals), and the PIC can only control this on it's outputs.  I don't know the specifics of exactly how it controls the slew rate, I guess some kind of compensation is applied around the pins output driver.
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>The electrical specifications in the back of the PICs datasheet should give the relevant rise/fall times.
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Yes, and there's is nothing depending on SSPSTAT<7>,
so therefor I concluded it doesn't do anything with the slew rate.

The only parameters that I could find,
which are *possible* involved in SSPSTAT<7> are
D034 ./ D034A and D044 / D044A
D034/D044 specifies the input high/low voltage range on RC3/RC4 with 
smitt-trigger enabled
D034A/D044A specifies the input high/low voltage range on RC3/RC4 with 
smitt-trigger disabled (also called SMbus)

Stef

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