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jds-pic



Joined: 17 Sep 2003
Posts: 205

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PostPosted: Sun Jan 20, 2008 9:30 am     Reply with quote
Humberto wrote:
Quote:
Interesting. If I disconnect the external power source for max232 there is no problems
reading from PIC

The MAX232 doesn't need any external power source. Is has a built in pump-switching DC/DC voltage converter to generate the required levels for RS232.


not true. you need to supply Vcc.

see
http://www.datasheetcatalog.com/datasheets_pdf/M/A/X/2/MAX232.shtml

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Humberto



Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata

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PostPosted: Sun Jan 20, 2008 11:34 am     Reply with quote
Of course that it need a power supply, like any electronic IC device, but the term "external
power source" is at least confused. Even more confused when he affirm that disconnecting
the power source, there is no problem. Cool

If all the devices that share the same board are powered by the same power supply
-it doesn't matter where the power supply is- the term "external" is never used.
Normally the transceiver is powered with the same supply used to power the MCU,
but being the transceiver a communication device, the term "external" is like if the device
is being powered by a remote power supply, which is possible and widely used in isolated
networks.


Humberto
ThomasC



Joined: 09 Oct 2007
Posts: 62

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PostPosted: Tue Jan 22, 2008 9:54 am     Reply with quote
This link may help you.

It got me connected a few months ago.

PIC-MAX232-RS232-PC
http://www.ccsinfo.com/forum/viewtopic.php?t=32455&highlight=
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