On Thu, 31 Jul 2003 18:27:40 +0300, you wrote:

>The cable is 100 meters long, would that count for "long" cable? =20
Definitely - I'd say "very long"!
a 100m cable connected only to 2 PIC pins is asking for trouble.

>-----Original Message-----
>From: pic microcontroller discussion list
>[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Mike Harrison
>Sent: Tuesday, July 29, 2003 1:51 PM
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [EE]: Reed switch and cable
>
>
>On Tue, 29 Jul 2003 12:03:48 +0200, you wrote:
>
>>Perhaps connect the reed switch between two PIC pins.
>>One output pin driven low when sampling the switch, the
>>other as input (with interal pullup enabled) to read the
>>switch. That way, the curcuit will only draw current when
>>the output port is driven low (even if the switch is
>>closed for a longer time).
>>
>>That is, if the impedance of the internal pullup is
>>enugh to filter out the cable noice.
>>
>>Jan-Erik.
>WIth a long cable you really want one side grounded for RF and ESD
>immunity.
>
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