Lpc2000

Leon Heller wrote:

>----- Original Message ----- 
>From: "Tom Walsh" <tom@...>
>To: <lpc2000@yahoogroups.com>
>Sent: Friday, February 03, 2006 3:19 PM
>Subject: Re: [lpc2000] Rise and fall time of capture inputs
>
>
>  
>
>>widescreen03608 wrote:
>>
>>    
>>
>>>Hi all,
>>>
>>>On the CAP0.3 input I have pulses from an encoder and I want detect
>>>both edges and generate interrupts. The signal is filtered so the rise
>>>and fall time are slow (don't know exactly how long, but surely within
>>>1ms). Is it possible that no interrupt is generated on CAP0.3, because
>>>the signal is to slow?
>>>
>>>I didn't found any datasheets from Philips which this is described.
>>>
>>>
>>>
>>>      
>>>
>>Aside from the datasheet thing, wouldn't it be possible to use a schmidt
>>gate to drive the capture intput?  Or some op-amp crossing-detector with
>>hysteresis?
>>    
>>
>
>I've done that in the past with that sort of input. I then had a problem 
>with multiple signals (like contact bounce) which I eliminated with 
>software.
>
>  
>
Yes, that is a given when dealing with mechanical contacts.  They do 
bounce.  As far as that goes, analog lines can "bounce", inductance.

TomW

-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
----------------------------------------------------