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Really Really confused with CAN Transmission and other questions

Question asked by rahul krishna on May 9, 2015
Latest reply on May 11, 2015 by Edward Karpicz

I am really confused with the following questions

 

1. I am trying to gateway messages from one channel to other channel in the same sequence as it receives. At one point of time i receive 3 messages and process them for transmission, but the program transmits first message and then starts transmitting the new messages received after the 3 messages, Some time later it transmits missing messages. I want to clarify if it is my software program error ?

2. If i transmit the three messages at a stretch without delay does the controller miss the sequence of messages and transmit when the bus is free. Is this scenario ever possible?

3. Currently if i transmit i am only setting the transmit interrupt bit to transmit the message. Is it possible that i know that the message is actually on the bus? Can i use this method of programming so that i becomes closed loop programming.

4. Between two CAN messages how much delay should i provide? Is there any standard? As i have seen different delays in different programs.

5. I use a semaphore for data coherency i lock a variable in the interrupt when receiving data. In the main routing i lock the same variable and copy to local variable and process. My main doubt is suppose i locked the variable in the main for longer time by mistake and in the mean time the interrupt happens in the xgate and finds the semaphore locked will it wait till the semaphore is unlocked or just comes out of interrupt without updating. Any error is generated in such cases?

sorry for a long list of questions. without the above clarifications i really cannot move further in the project.

 

Thanks in advance.

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