you've made me curious now...

is the 4.7K resistor there to prevent the pin from
'recieving' too much current when nothing is being done
on the pin?

(or maybe when the pin is floating...)

the 470 is there to take away current from the led

and I know that if you toggle the pin,
with only the LED and the 470, it will work

So, I guess, you have to maintain it in a 1 state to
keep it from taking in too much current....

I'm just guessing here

any help is appreciated, thanks




----- Original Message -----
From: "Spehro Pefhany" <speff@INTERLOG.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, January 23, 2003 8:24 PM
Subject: Re: [pic]: pic16F877 and RA4


> At 04:03 PM 1/23/03 -0600, you wrote:
>
> >this has come about because I cannot get the LED to blink on this pin,
RA4
> >
> >I tried setting adcon1 to 6, and trisa to 0
> >but there is something else, or all my pics are damaged exactly the same
> >way.
>
> Here's a good starting point for blinking an LED with RA4. When you
> understand why the 4K7 is in there, you can probably write software
> that allows you to leave it out. ;-)
>
>                             Vdd
>                              +
>                    +---------+-----+
>                    |               |
>                    |              .-.
>                Vdd |              | |470R
>            .-------o-----.        | |
>            |             |        '-'
>            |             |         +--------+
>            |  PIC        |    LED  |        |
>            |             |         V /     .-.
>            |             |         - /     | |
>            |             | RA4     |       | |
>            |          +--o----+    |    4K7'-'
>            |          |  |    |    |        |
>            |          |  |    +----+--------+
>            |       ||-+  |
>            |       ||<-  |
>            |      -||-+  |
>            |          |  |
>            |          |  |
>            |          |  |
>            '----------|--'
>                      ===
>                      GND
>
> (view in fixed-width font)
>
>
> Best regards,
>
> Spehro Pefhany --"it's the network..."            "The Journey is the
reward"
> speff@interlog.com             Info for manufacturers:
http://www.trexon.com
> Embedded software/hardware/analog  Info for designers:
http://www.speff.com
>
> --
> http://www.piclist.com hint: The list server can filter out subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.