• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 84 subscribers
  • Views 1394 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Set F28335 eCAN transmit message time!!

Vennela Yadhati
Prodigy 70 points

Other Parts Discussed in Thread: TMS320F28335

Hi,

I'm using the TMS320F28335 chip and I want to set the transmit time of a message to 100ms. I know how to set the baud rate (I set it to 500kbps) and all. But what do I do to set the transmit message to 100ms (so, it is transmitted every 100ms?

For eg, if I send a message at say, 231.2748, I want it to send the same message again at 231.3748. How do I do this?

I'm a beginner and this is my first time programming a DSP. So, any help is much appreciated!! :)

  • 0
    Expert 2220 points

    I'm not an expert on CAN, but if I were to do this on the other communication channels (SCI, SPI, McBSP, etc.) I would use a timer interrupt.

    Have you looked into using the Timer0 module?  With this, you can set it to trigger an interrupt every 100ms and in that interrupt you can trigger a CAN transmit.

    If all your Timers are already allocated for something (which, I can't imagine why); you can also use an ECAP to produce timer interrupts.

  • 0 in reply to quark
    Prodigy 70 points

    Can I make use of the Time stamp counter register bits? Like the MOTS which stores the value of the TSC?

    can I use it like

    (if ECanaRegs.CANTSC.bit.MOTS19=100ms)

    {

    ECanaShadow.CANTRS.bit.TRS19 = 1;

    }

    to transmit the mailbox19 data?

     

    Thanks,

    VY

  • 0 in reply to Vennela Yadhati
    Mastermind 7585 points

    Your code will not work. CANTSC will hold the time of the last transmission.

    What you can do is to use the MOTO feature. If you load MOTO = CANLNT + 100 ms, then you can use the MOTO-Interrupt Service to start a new transmission. However, the accuracy of the CAN- Time is limited to the CAN data rate (1Mbit/s = 1 µs) , wehereas a solution based on a CPU timer wll use an accuracy of the CPU frequency (150MHz = 6.6 ns).

     

  • 0
    Prodigy 70 points

    Hi,

    use a timer and enable an interrupt. when the DSP goes to the interrupt, start CAN transmission, reset the timer, clear the interrupt.

    alternatively, if you already have a base time, for instance PWM modulator enabled, just count the number on PWM cycles...I suppose the PWM frequency is higher than the CAN TX frequency