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???
10/29/09 14:04
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 		 #170186 - Synchronize transfers
Responding to: ???'s previous message
Three issues.

Connecting two TX outputs without having the two outputs fighting electrically is a special case for standard 8051 chips. It is only possible when the chip have open-collector outputs with internal, weak, pull-up. The world is full of processors that have full push-pull designs. Always, or when using the pin together with the UART.

The second issue is that two TX signals connected together will result in garbage, unless the software in the two processors has logic to synchronize the transfers. When one processor sends, the other processor must leave the TX signal in idle. You may synchronize by sending explicit addressed requests from the PC. The uC with the matching address responds while the other uC is silent. Then request data from the other uC in the same way.

The third issue is that Keil do not have any C# compiler for 8051. C-sharp is originally intended for writing Windows applications, but with some limitations, you will be able to find a couple of other supported platforms. Chosing Keil and 8051, you will have to settle for using C or assembler.

List of 71 messages in thread
TopicAuthorDate
Communication between two 8051            01/01/70 00:00      
   I'm going to recommend            01/01/70 00:00      
      I'm going to recommend            01/01/70 00:00      
   I'd recommend ...            01/01/70 00:00      
      irrelevant, however            01/01/70 00:00      
      chip            01/01/70 00:00      
         multiple chips ....            01/01/70 00:00      
            Perhaps you don't need two UARTs            01/01/70 00:00      
   Side note, multiple COM ports            01/01/70 00:00      
      FTDI Multi-UART to USB            01/01/70 00:00      
   Clarify?            01/01/70 00:00      
   Parallel 8051 TXs and RXs            01/01/70 00:00      
      Two transmitters            01/01/70 00:00      
         Which lesson to give?            01/01/70 00:00      
            and ..            01/01/70 00:00      
            Like good little children            01/01/70 00:00      
            Jimmy Neutron/Phineas & Ferb            01/01/70 00:00      
            Tony Gelonese's method should work...            01/01/70 00:00      
               no, and yes            01/01/70 00:00      
         some more thought...Per Westermark            01/01/70 00:00      
            It is all in the subpressed details            01/01/70 00:00      
               SIlabs chips would burn            01/01/70 00:00      
      No, That won't "just work"            01/01/70 00:00      
         I think there's more to this than meets the eye            01/01/70 00:00      
            Not always interrupt response instantly            01/01/70 00:00      
               Since the O/P hasn't been back ...            01/01/70 00:00      
                  serial communication            01/01/70 00:00      
                     you are aware?            01/01/70 00:00      
                        You are also aware?            01/01/70 00:00      
                     Synchronize transfers            01/01/70 00:00      
                        Connecting two TX outputs            01/01/70 00:00      
                     Unnecessary complication!            01/01/70 00:00      
                        Different name            01/01/70 00:00      
                        Walter and Walter            01/01/70 00:00      
                           Name            01/01/70 00:00      
                              what are you ashamed/afraid/... of            01/01/70 00:00      
                              Walter, Please eschew obfuscation and equivocation            01/01/70 00:00      
                     That Phytec Board has RS485 and I2C and SPI            01/01/70 00:00      
                        summarizing            01/01/70 00:00      
                           to a nail everything looks like a hammer            01/01/70 00:00      
                        actually ... he hasn't said he needs that ...            01/01/70 00:00      
                           Often important information arrives quite late            01/01/70 00:00      
                           Actually, he did!            01/01/70 00:00      
                              It's not complete            01/01/70 00:00      
                                 he's so stingy with information            01/01/70 00:00      
   Some more Thought....            01/01/70 00:00      
      This assumes perfect synchronization            01/01/70 00:00      
      the longest reply ever            01/01/70 00:00      
         Schematic is Incomplete            01/01/70 00:00      
      Missing boundary limits            01/01/70 00:00      
         Use p3.0 and p3.1            01/01/70 00:00      
            huh?            01/01/70 00:00      
            You need to clarify your requirement!            01/01/70 00:00      
            This contradicts an earlier post from you            01/01/70 00:00      
               agree with most, but???            01/01/70 00:00      
                  clock-for-clock send            01/01/70 00:00      
                     Still not clear!            01/01/70 00:00      
                        I think you lost the thread            01/01/70 00:00      
                           If they're to remain in precise synchronization ...            01/01/70 00:00      
                              Ridiculous            01/01/70 00:00      
                                 Come on, Walter!            01/01/70 00:00      
                                 It's routinely done ...            01/01/70 00:00      
                                    Don't relive your past again and again            01/01/70 00:00      
                                       MCU is a component, not a computer system.            01/01/70 00:00      
                                          Tell me more about femtosecond precision            01/01/70 00:00      
                                             not even then            01/01/70 00:00      
                                                Watch out            01/01/70 00:00      
                                                   Some suggestions for low-jitter processor activation            01/01/70 00:00      
                                                That's exactly what it is            01/01/70 00:00      
                  The two slaves must be in the same state            01/01/70 00:00      
            Is this yet another problem?            01/01/70 00:00      

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