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10/29/08 13:08
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 		 #159474 - Interfacing RS485 (SN75176) with AT89c51
I need help with my project "Menu card automation".The idea is to use multiple slaves at different tables which display the menu on a 16x2 lcd display and the patron selects an item by scrolling up& down, using a keypad ,and then hitting enter( I intend to use a 4 i/p keypad only).Ofcourse the slaves need to communicate this information to the master,I intend to use RS485 protocol (because multidrop).The master also communicates this info to kitchen via a pc thru max232. But I am stuck on two things
1.I intend to use a SN75176-SN65176 TRANSCEIVER for RS485 , but HOW exactly this 8pin IC would assist in communication is a question i've not been able to answer. (terminal resistance would be 120ohms). data sheet has been quite redundant..i wish to know as to how exactly it works.If you could explain that; it would be great or any pointers towars any suitable sites with positive , complete information is quite welcome too.
2.The master is to communicate with multiple slaves, and also with the PC. but AT89c51 has only one UART!!! what's the work around?
ANY GUIDANCE OR ASSISTANCE IN THE RIGHT DIRECTION IS INDEED VERY WELCOME.
& thx in advance.


List of 24 messages in thread
TopicAuthorDate
Interfacing RS485 (SN75176) with AT89c51            01/01/70 00:00      
   Select your components with care            01/01/70 00:00      
   Compnents are irreplacable !!            01/01/70 00:00      
      What do you miss in the datasheet            01/01/70 00:00      
      It is a simple chip            01/01/70 00:00      
   do not do rs485 without ...            01/01/70 00:00      
   Here's the info for starting            01/01/70 00:00      
   Controlling the sn75176!!            01/01/70 00:00      
      use the \"industrial strangth\" LT1785 instead            01/01/70 00:00      
         Easy to control the RS-485 transeciever            01/01/70 00:00      
            this is one of the biggest mistakes in RS485            01/01/70 00:00      
               Not so much specific for RS-485            01/01/70 00:00      
               might be???            01/01/70 00:00      
                  These are NOT RS485            01/01/70 00:00      
                     Lack of dominant bit state            01/01/70 00:00      
                        that's exactly why on RS485...            01/01/70 00:00      
                           Token-passing requires explicit or arbitrated mast            01/01/70 00:00      
                        the amazing thing is ...            01/01/70 00:00      
                           ... that it matter            01/01/70 00:00      
                              I am NOT talking about multiple masters, ...            01/01/70 00:00      
      follow the link            01/01/70 00:00      
         the two REAL 485 sources            01/01/70 00:00      
            Preview?            01/01/70 00:00      
               I do not know why            01/01/70 00:00      

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