max485 problem with comm

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sherazi
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Joined: Sun. Mar 21, 2010
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Posted by sherazi: Sun. Oct 31, 2010 - 05:56 AM
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regards ...
i made this circuit [plz consider just the max485 only ...but when i used it it didn't received any thing although transmission was all good, then i tried some debugging and found that on removing r14,r15,and r18 it works..
although i get a character y' all the time when i change from transmission to reception ...

plz help me why i get this..

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AVR Microcontrollers, megaAVR and tinyAVR
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Kartman
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Joined: Thu. Dec 30, 2004
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Location: Melbourne,Australia
Posted by Kartman: Sun. Oct 31, 2010 - 07:26 AM
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With no data, pin 1 of the max485 should be at a logic 1. According to your circuit, the bias resistors will make it logic 0. Reverse the bias resistors and it should work better.

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