• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 83 subscribers
  • Views 319 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.

CCS/TMS320F28379D: ecap

Robot Jarvis
Intellectual 300 points
Part Number: TMS320F28379D


Tool/software: Code Composer Studio

Dear support team:

 Hello, I want to know how to judge the rising edge and falling edge of the ecap module.

Will the rising and falling edges of the circled part like the following picture be captured by ecap?

 

  • 0
    TI__Mastermind 24095 points

    Hi,

    No, the circled parts seem to be the spikes over existing signal. They do not effect ECAP operation.
    ECAP will detect transition when signal changes state from 0 to 1 or 1 to 0 depending on the configuration.

  • 0 in reply to Subrahmanya
    Intellectual 300 points

    hi，

      The two signals in the figure are the signals of A phase and B phase of INC encoder. I use two ECAP modules to capture the two signals. The configuration is as follows：

       ECap1Regs.ECCTL1.bit.CAP1POL = 0;      //rising
       ECap1Regs.ECCTL1.bit.CAP2POL = 1;      //fall
       ECap1Regs.ECCTL1.bit.CAP3POL = 0;      //rising
       ECap1Regs.ECCTL1.bit.CAP4POL = 1;      //fall

       ECap1Regs.ECCTL1.bit.CTRRST1 = 1;       // 1:delta  0:abs
       ECap1Regs.ECCTL1.bit.CTRRST2 = 1;       // 1:delta  0:abs
       ECap1Regs.ECCTL1.bit.CTRRST3 = 1;       // 1:delta  0:abs
       ECap1Regs.ECCTL1.bit.CTRRST4 = 1;       // 1:delta  0:abs

       ECap1Regs.ECCTL1.bit.CAPLDEN = 1;       // Enable capture units
       ECap1Regs.ECCTL1.bit.PRESCALE = 0;      // /1

       ECap1Regs.ECCTL2.bit.CAP_APWM = 0;      //capture mode
       ECap1Regs.ECCTL2.bit.CONT_ONESHT = 0;   //continuous mode
       ECap1Regs.ECCTL2.bit.SYNCO_SEL =2;      //disable syn output
       ECap1Regs.ECCTL2.bit.SYNCI_EN = 0;      //disable syn input

       ECap1Regs.ECEINT.all = 0x0000;
       ECap1Regs.ECCLR.all = 0xFFFF;
       ECap1Regs.ECCTL2.bit.TSCTRSTOP = 1;     // Start Counter
       ECap1Regs.ECEINT.bit.CEVT4 = 1;         // 4 events = __interrupt

       ECap2Regs.ECCTL1.bit.CAP1POL = 0;      //rising
       ECap2Regs.ECCTL1.bit.CAP2POL = 1;      //fall
       ECap2Regs.ECCTL1.bit.CAP3POL = 0;      //rising
       ECap2Regs.ECCTL1.bit.CAP4POL = 1;      //fall

       ECap2Regs.ECCTL1.bit.CTRRST1 = 1;      // 1:delta  0:abs
       ECap2Regs.ECCTL1.bit.CTRRST2 = 1;      // 1:delta  0:abs
       ECap2Regs.ECCTL1.bit.CTRRST3 = 1;      // 1:delta  0:abs
       ECap2Regs.ECCTL1.bit.CTRRST4 = 1;       // 1:delta  0:abs

       ECap2Regs.ECCTL1.bit.CAPLDEN = 1;       // Enable capture units
       ECap2Regs.ECCTL1.bit.PRESCALE = 0;      // /1

       ECap2Regs.ECCTL2.bit.CAP_APWM = 0;      //capture mode
       ECap2Regs.ECCTL2.bit.CONT_ONESHT = 0;   //continuous mode
       ECap2Regs.ECCTL2.bit.SYNCO_SEL =2;      //disable syn output
       ECap2Regs.ECCTL2.bit.SYNCI_EN = 0;      //disable syn input

       ECap2Regs.ECEINT.all = 0x0000;
       ECap2Regs.ECCLR.all = 0xFFFF;
       ECap2Regs.ECCTL2.bit.TSCTRSTOP = 1;     // Start Counter
       ECap2Regs.ECEINT.bit.CEVT4 = 1;         // 4 events = __interrupt
    Will the tip pulse on the signal be captured by the ECAP as a rising or falling edge?

  • 0 in reply to Robot Jarvis
    TI__Mastermind 24095 points

    Hi,

    Robot Jarvis said:
    Will the tip pulse on the signal be captured by the ECAP as a rising or falling edge?

    As I said earlier, tip of the pulse does not matter. ECAP will detect transition when signal changes state from 0 to 1 or 1 to 0 depending on the configuration.

    So, the voltage level of the input signal when it transitions from 0 to 1 or 1 to 0 is then the edge is detected.
    You can consider to be roughly half of input voltage (3.3v). For accurate specs, refer Vih/Vil parameters in the data sheet.
    Nothing happens at the peaks you've indicated in the diagram - for the operation of eCAP they have no effect.