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Test Schematic

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Radiken:
I designed my first schematic, and It would be nice to get it checked out from someone with experience  before I start building...

http://aycu13.webshots.com/image/17492/2005621959605693018_rs.jpg

dunk:
hi Radiken,
so the only thing i can see wrong is the lack of charge capacitors on the MAX232.
the MAX232 has to generate voltages in excess of VDD for communication with RS232 devices.
it does this using a charge pump and stores the power in capacitors.

there should be capacitors between pin 2 (V+) and VDD
and between pin 6 (V-) and VSS.

just to add confusion, the Eagle package you used to create your circuit diagram doesn't show you the actual connection to VSS and VDD.
it just presumes these exist.

all this is clearer if you just look at figure 5. here:
http://datasheets.maxim-ic.com/en/ds/MAX220-MAX249.pdf

the only other thing i might be concerned about is the maximum current provided by the MAX667. glancing at the datasheet, it's only rated up to 250mA.
from experience, it's always worth putting a voltage regulator on your circuitthat can provide as much current as possible.
one servo could draw 250mA when under load.
as long as you don't intend to run anything power hungry off this regulator you should be allright though.

dunk.

dunk:
oops, i missed something obvious.
i don't theink the pic16f877 has an internal oscilator.
you are going to need a timing circuit.
(section 12.2 of the datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/30292c.pdf)

dunk.

Radiken:
I've never had to deal with oscillators until now,(As I said, this is my first board) so how do I figure what frequency of crystal to use? ???

JonHylands:
You can use a ceramic resonator - if you buy one that has bulit-in capacitors, you only need the one component - they have three legs. You would connect each of the outer pins to one of pins 13 and 14, and the center pin to ground.

You can use any frequency you like, up to 20 MHz. I typically use 20 MHz on my PIC projects.

Digikey part# X909-ND would do the trick, and will cost 53 cents.

- Jon

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