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???
02/15/10 22:15
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 		 #173187 - Check sum not good enough
Responding to: ???'s previous message
Peter:
The checksum is not a good full solution. The use of the checksum presumes that the protocol over the bus is implemented to the level of capability that packets can pass and then so be checked. However the distortion in I2C bus signalling that can occur due to rise and fall time issues can lead to the transaction handshaking not even being able to complete. In the most basic case you could fail to get an ACK back from an addressed slave device during the slave address transfer cycle. Worst yet another device than the one you tried to address may think you are trying to talk to him!!

Do consider taking a close look at using an MCU that has a hardware module on board that runs in SMBus mode.
Michael Karas

List of 31 messages in thread
TopicAuthorDate
Bus between modules            01/01/70 00:00      
   Questions            01/01/70 00:00      
      RS-485?            01/01/70 00:00      
         RS-485 or CAN would both work            01/01/70 00:00      
      Answers to questions            01/01/70 00:00      
         Check sum not good enough            01/01/70 00:00      
            Noise            01/01/70 00:00      
               has to work is on stage (music).            01/01/70 00:00      
                  MIDI/DMX            01/01/70 00:00      
                     capacitance, capacitance, capacitance            01/01/70 00:00      
                        I2C feasible ....            01/01/70 00:00      
         Replies to quesitons in answers!            01/01/70 00:00      
         UART            01/01/70 00:00      
            SPI-to-UART with Drivers!            01/01/70 00:00      
               A confession            01/01/70 00:00      
            Not necessarily            01/01/70 00:00      
               Controller type            01/01/70 00:00      
                  I just have [not] decided yet.            01/01/70 00:00      
                     Chips with two UARTS            01/01/70 00:00      
                         not true            01/01/70 00:00      
                           P89LPC952            01/01/70 00:00      
                              Let's assume I'm going to use a UART.            01/01/70 00:00      
                              did you try here?            01/01/70 00:00      
   I2C Could be made to work.            01/01/70 00:00      
      RE: SMBus            01/01/70 00:00      
         so does SMB            01/01/70 00:00      
            For the sake of completeness            01/01/70 00:00      
               not really            01/01/70 00:00      
                  I see            01/01/70 00:00      
                     Timeouts and Hold Times.            01/01/70 00:00      
                        Specifications!            01/01/70 00:00      

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