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eQEP增强型正交编码模块原理介绍及配合MircoE mercury II 4000光栅传感器使用

2019-07-13 20:05发布

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1、首先介绍MircoE mercury II 4000光栅传感器串口PIN及对应功能（male D-sub connector）
正交TTL电平（标准为低电平0，高电平1（+5v）） 差分信号















由于光栅传感器一般意义上有转动和直线两种： 对于直线光栅来说，一般考虑的是位移信号，相对位移=（当前QPOSCNT的值- 开始时QPOSCNT的值）* 光栅分辨率（count / m）； 对于转动光栅来说，一般考虑的是机械角度和电角度，机械角度是空间转过一周的这一般分为两种计算转速的方式 1、在高速时，M测速法：
2、在低速时，T测速法：
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 Calculation 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 else Tmp1 = newp -oldp; } else if (p->DirectionQep==1) // POSCNT is counting up { if (newp_IQ(1)) p->Speed_fr = _IQ(1); else if (Tmp1<_IQ(-1)) p->Speed_fr = _IQ(-1); else p->Speed_fr = Tmp1; // Update the electrical angle p->oldpos = newp; // Change motor speed from pu value to rpm value (Q15 -> Q0) // Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q p->SpeedRpm_fr = _IQmpy(p->BaseRpm,p->Speed_fr); //======================================= EQep1Regs.QCLR.bit.UTO=1; // Clear interrupt flag }//**** Low-speed computation using QEP capture counter ****// if(EQep1Regs.QEPSTS.bit.UPEVNT==1) // Unit position event { if(EQep1Regs.QEPSTS.bit.COEF==0) // No Capture overflow temp1=(unsigned long)EQep1Regs.QCPRDLAT; // temp1 = t2-t1 else // Capture overflow, saturate the result temp1=0xFFFF; p->Speed_pr = _IQdiv(p->SpeedScaler,temp1); // p->Speed_pr = p->SpeedScaler/temp1 Tmp1=p->Speed_pr; if (Tmp1>_IQ(1)) p->Speed_pr = _IQ(1); else p->Speed_pr = Tmp1; // Convert p->Speed_pr to RPM if (p->DirectionQep==0) // Reverse direction = negative p->SpeedRpm_pr = -_IQmpy(p->BaseRpm,p->Speed_pr); // Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q else // Forward direction = positive p->SpeedRpm_pr = _IQmpy(p->BaseRpm,p->Speed_pr); // Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q EQep1Regs.QEPSTS.all=0x88; // Clear Unit position event flag // Clear overflow error flag } }

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