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//########################################################################### // // FILE: Example_posspeed.c // // TITLE: Pos/speed measurement using EQEP peripheral // // DESCRIPTION: // // This file includes the EQEP initialization and position and speed calcuation // functions called by Example_2833xEqep_posspeed.c. The position and // speed calculation steps performed by POSSPEED_Calc() at SYSCLKOUT = 150 MHz // and 100 MHz are described in detail below: // // For 150 MHz Operation: // ---------------------- // // 1. This program calculates: **theta_mech** // // theta_mech = QPOSCNT/mech_Scaler = QPOSCNT/4000, where 4000 is the number of // counts in 1 revolution.(4000/4 = 1000 line/rev. quadrature encoder) // // 2. This program calculates: **theta_elec** // // theta_elec = (# pole pairs) * theta_mech = 2*QPOSCNT/4000 for this example // // 3. This program calculates: **SpeedRpm_fr** // // SpeedRpm_fr = [(x2-x1)/4000]/T - Equation 1 // Note (x2-x1) = difference in number of QPOSCNT counts. Dividing (x2-x1) by // 4000 gives position relative to Index in one revolution. // If base RPM = 6000 rpm: 6000 rpm = [(x2-x1)/4000]/10ms - Equation 2 // = [(x2-x1)/4000]/(.01s*1 min/60 sec) // = [(x2-x1)/4000]/(1/6000) min // max (x2-x1) = 4000 counts, or 1 revolution in 10 ms // // // If both sides of Equation 2 are divided by 6000 rpm, then: // 1 = [(x2-x1)/4000] rev./[(1/6000) min * 6000rpm] // Because (x2-x1) must be <4000 (max) for QPOSCNT increment, // (x2-x1)/4000 < 1 for CW rotation // And because (x2-x1) must be >-4000 for QPOSCNT decrement, // (x2-x1)/4000>-1 for CCW rotation // speed_fr = [(x2-x1)/4000]/[(1/6000) min * 6000rpm] // = (x2-x1)/4000 - Equation 3 // // To convert speed_fr to RPM, multiply Equation 3 by 6000 rpm // SpeedRpm_fr = 6000rpm *(x2-x1)/4000 - Final Equation // // // 2. **min rpm ** = selected at 10 rpm based on CCPS prescaler options available (128 is greatest) // // 3. **SpeedRpm_pr** // SpeedRpm_pr = X/(t2-t1) - Equation 4 // where X = QCAPCTL [UPPS]/4000 rev. (position relative to Index in 1 revolution) // If max/base speed = 6000 rpm: 6000 = (32/4000)/[(t2-t1)/(150MHz/128)] // where 32 = QCAPCTL [UPPS] (Unit timeout - once every 32 edges) // 32/4000 = position in 1 revolution (position as a fraction of 1 revolution) // t2-t1/(150MHz/128), t2-t1= # of QCAPCLK cycles, and // 1 QCAPCLK cycle = 1/(150MHz/128) // = QCPRDLAT // // So: 6000 rpm = [32(150MHz/128)*60s/min]/[4000(t2-t1)] // t2-t1 = [32(150MHz/128)*60 s/min]/(4000*6000rpm) - Equation 5 // = 94 CAPCLK cycles = maximum (t2-t1) = SpeedScaler // // Divide both sides by (t2-t1), and: // 1 = 94/(t2-t1) = [32(150MHz/128)*60 s/min]/(4000*6000rpm)]/(t2-t1) // Because (t2-t1) must be < 94 for QPOSCNT increment: // 94/(t2-t1) < 1 for CW rotation // And because (t2-t1) must be >-94 for QPOSCNT decrement: // 94/(t2-t1)> -1 for CCW rotation // // speed_pr = 94/(t2-t1) // or [32(150MHz/128)*60 s/min]/(4000*6000rpm)]/(t2-t1) - Equation 6 // // To convert speed_pr to RPM: // Multiply Equation 6 by 6000rpm: // SpeedRpm_fr = 6000rpm * [32(150MHz/128)*60 s/min]/[4000*6000rpm*(t2-t1)] // = [32(150MHz/128)*60 s/min]/[4000*(t2-t1)] // or [(32/4000)rev * 60 s/min]/[(t2-t1)(QCPRDLAT)]- Final Equation // // // For 100 MHz Operation: // ---------------------- // // The same calculations as above are performed, but with 100 MHz // instead of 150MHz when calculating SpeedRpm_pr. // The value for freqScaler_pr becomes: [32*(100MHz/128)*60s/min]/(4000*6000rpm) = 63 // More detailed calculation results can be found in the Example_freqcal.xls // spreadsheet included in the example folder. // // // // This file contains source for the posspeed module // //########################################################################### // Original Author: SD // // $TI Release: 2833x/2823x Header Files and Peripheral Examples V133 $ // $Release Date: June 8, 2012 $ //########################################################################### #include "DSP28x_Project.h" // Device Headerfile and Examples Include File #include "Example_posspeed.h" // Example specific Include file void POSSPEED_Init(void) { #if (CPU_FRQ_150MHZ) EQep1Regs.QUPRD=1500000; // Unit Timer for 100Hz at 150 MHz SYSCLKOUT #endif #if (CPU_FRQ_100MHZ) EQep1Regs.QUPRD=1000000; // Unit Timer for 100Hz at 100 MHz SYSCLKOUT #endif EQep1Regs.QDECCTL.bit.QSRC=00; // QEP quadrature count mode EQep1Regs.QEPCTL.bit.FREE_SOFT=2; EQep1Regs.QEPCTL.bit.PCRM=00; // PCRM=00 mode - QPOSCNT reset on index event EQep1Regs.QEPCTL.bit.UTE=1; // Unit Timeout Enable EQep1Regs.QEPCTL.bit.QCLM=1; // Latch on unit time out EQep1Regs.QPOSMAX=0xffffffff; EQep1Regs.QEPCTL.bit.QPEN=1; // QEP enable EQep1Regs.QCAPCTL.bit.UPPS=5; // 1/32 for unit position EQep1Regs.QCAPCTL.bit.CCPS=7; // 1/128 for CAP clock EQep1Regs.QCAPCTL.bit.CEN=1; // QEP Capture Enable } void POSSPEED_Calc(POSSPEED *p) { long tmp; unsigned int pos16bval,temp1; _iq Tmp1,newp,oldp; //**** Position calculation - mechanical and electrical motor angle ****// p->DirectionQep = EQep1Regs.QEPSTS.bit.QDF; // Motor direction: 0=CCW/reverse, 1=CW/forward pos16bval=(unsigned int)EQep1Regs.QPOSCNT; // capture position once per QA/QB period p->theta_raw = pos16bval+ p->cal_angle; // raw theta = current pos. + ang. offset from QA // The following lines calculate p->theta_mech ~= QPOSCNT/mech_scaler [current cnt/(total cnt in 1 rev.)] // where mech_scaler = 4000 cnts/revolution tmp = (long)((long)p->theta_raw*(long)p->mech_scaler); // Q0*Q26 = Q26 tmp &= 0x03FFF000; p->theta_mech = (int)(tmp>>11); // Q26 -> Q15 p->theta_mech &= 0x7FFF; // The following lines calculate p->elec_mech p->theta_elec = p->pole_pairs*p->theta_mech; // Q0*Q15 = Q15 p->theta_elec &= 0x7FFF; // Check an index occurrence if (EQep1Regs.QFLG.bit.IEL == 1) { p->index_sync_flag = 0x00F0; EQep1Regs.QCLR.bit.IEL=1; // Clear interrupt flag } //**** High Speed Calcultation using QEP Position counter ****// // Check unit Time out-event for speed calculation: // Unit Timer is configured for 100Hz in INIT function if(EQep1Regs.QFLG.bit.UTO==1) // If unit timeout (one 100Hz period) { /** Differentiator **/ // The following lines calculate position = (x2-x1)/4000 (position in 1 revolution) pos16bval=(unsigned int)EQep1Regs.QPOSLAT; // Latched POSCNT value tmp = (long)((long)pos16bval*(long)p->mech_scaler); // Q0*Q26 = Q26 tmp &= 0x03FFF000; tmp = (int)(tmp>>11); // Q26 -> Q15 tmp &= 0x7FFF; newp=_IQ15toIQ(tmp); oldp=p->oldpos; if (p->DirectionQep==0) // POSCNT is counting down { if (newp>oldp) Tmp1 = - (_IQ(1) - newp + oldp); // x2-x1 should be negative