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ECAP1 capture for C6748 setup

David Luca
Expert 2795 points


Hello,

I've been trying to setup ECAP1 in delta-mode to capture a square signal, but the capture events are not changing, I only read 0, could you have a look at the code below please, maybe you can spot something? 

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PSCModuleControl(SOC_PSC_1_REGS, HW_PSC_ECAP0_1_2, PSC_POWERDOMAIN_ALWAYS_ON,  PSC_MDCTL_NEXT_ENABLE);
 
//Select Pin E4 ECAP1
/* ECAP1 */
HWREG(SOC_SYSCFG_0_REGS + SYSCFG0_PINMUX(1)) =  (HWREG(SOC_SYSCFG_0_REGS + SYSCFG0_PINMUX(1)) & (~(SYSCFG_PINMUX1_PINMUX1_31_28))) | (SYSCFG_PINMUX1_PINMUX1_31_28_ECAP1 << SYSCFG_PINMUX1_PINMUX1_31_28_SHIFT);
 
ECAPCaptureLoadingEnable(SOC_ECAP_1_REGS);
 
ECAPOperatingModeSelect(SOC_ECAP_1_REGS, ECAP_CAPTURE_MODE);
 
ECAPPrescaleConfig(SOC_ECAP_1_REGS, 0);//no prescale
 
 
ECAPCapeEvtPolarityConfig(SOC_ECAP_1_REGS, 1, 1, 1, 1);//rising, rising, rising, rising edges so that after 3 rising edges I have full rotation
 
ECAPCaptureEvtCntrRstConfig(SOC_ECAP_1_REGS, 1, 1, 1, 1 );//reset counter each time rising edge is found
 
ECAPContinousModeConfig(SOC_ECAP_1_REGS);   //set ecap in continuous mode to measure speed continuously
 
ECAPIntDisable(SOC_ECAP_1_REGS, ECAP_CEVT1_INT | ECAP_CEVT2_INT | ECAP_CEVT3_INT | ECAP_CEVT4_INT | ECAP_CNTOVF_INT | ECAP_PRDEQ_INT | ECAP_CMPEQ_INT);
 
ECAPSyncInOutSelect(SOC_ECAP_1_REGS, ECAP_SYNC_IN_DISABLE, ECAP_SYNC_OUT_DISABLE);
 
ECAPCounterConfig(SOC_ECAP_1_REGS, 0);//capture time base   =>reset ecap
ECAPCounterControl(SOC_ECAP_1_REGS, ECAP_COUNTER_FREE_RUNNING);//timer base counter to increase
Thank you in advance,
David.
  • 0
    Expert 2795 points

    Hello,

    I think I found the problems:

    In ecap.h the definitions for the ECAP_CAPTURE_MODE parameter for ECAPOperatingModeSelect function should be 0 instead of 1

    #define ECAP_CAPTURE_MODE 0 //check page spruh79a.pdf, bit 9
    #define ECAP_APWM_MODE 1  ...correction, it was ok, ECAPOperatingModeSelect is a bit confusing, set parameter to 1 to clear bit.

    Also, for ECAPSyncInOutSelect function the definitions are wrong, it overwrites the bit 9 setting it back to pwm mode

    #define ECAP_SYNC_IN (00 << ECAP_ECCTL2_SYNCO_SEL_SHIFT)    
    #define ECAP_PRD_EQ (01 << ECAP_ECCTL2_SYNCO_SEL_SHIFT)   
    #define ECAP_SYNC_OUT_DISABLE (10 << ECAP_ECCTL2_SYNCO_SEL_SHIFT)  //this should be 2 <<

    Hope someone can confirm this.

    Best regards,

    David.