272 lines
9.0 KiB
C
272 lines
9.0 KiB
C
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//###########################################################################
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//
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// FILE: Example_freqcal.c
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//
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// TITLE: EXAMPLE_FREQCAL_C Frequency Calculation
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//
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//! \addtogroup f2833x_example_list
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//! \section EXAMPLE_FREQCAL_C Frequency Calculation (Example_freqal.c)
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//!
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//! This file includes the EQEP initialization and frequency calculation
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//! functions called by \b Example_2833xEqep_freqcal.c.
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//! The frequency calculation steps performed by FREQCAL_Calc()at
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//! SYSCLKOUT = 150 MHz and 100 MHZ are described below:
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//!
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//! -# This program calculates: \b **freqhz_fr** for SYSCLKOUT = 150MHz \n
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//! \f[ freqhz\_fr\ or\ v = \frac{x_{2}-x_{1}}{T} .......... 1 \f] \n
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//! If \f[ \frac{max}{base}\ freq = 10kHz => 10kHz = \
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\frac{x_{2}-x_{1}}{(2/100Hz)} .......... 2\f] \n
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//! \f[ max (x_{2}-x_{1}) = 200 counts = freqScaler\_fr \f]
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//!
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//! \note \f$ T = \frac{2}{100Hz} \f$ . 2 is from \f$ \frac{x_{2}-x_{1}}{2}\f$
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//! because QPOSCNT counts 2 edges per cycle (rising and falling)
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//!
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//! If both sides of Equation 2 are divided by 10 kHz, then: \n
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//! \f[ 1 = \frac{x_{2}-x_{1}}{10kHz*(2/100Hz)}\f]\n where,
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//! \f[ [10kHz*\frac{2}{100Hz}] = 200 \f]\n
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//! Because \f[ x_{2}-x_{1} < 200 (max)\f]
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//! \f[ \frac{x_{2}-x_{1}}{200} < 1 \f]\n for all frequencies less than max\n
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//! \f[ freq\_fr = \frac{x_{2}-x_{1}}{200}\ or\ \
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\frac{x_{2}-x_{1}}{10kHz*(2/100Hz)} .......... 3\f] \n
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//!
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//! To get back to original velocity equation, Equation 1, multiply
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//! Equation 3 by 10 kHz\n
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//! \f[ freqhz\_fr(or\ velocity) = \
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10kHz*\frac{x_{2}-x_{1}}{10kHz*(2/100Hz)}\f]\n
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//! \f[ = \frac{x_{2}-x_{1}}{(2/100Hz)} .......... final\ equation\f] \n
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//!
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//! -# \b **min \b freq** \f$ = \frac{1\ count}{(2/100Hz)} = 50 Hz\f$
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//! -# \b **freqhz_pr** \n
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//! \f[ freqhz\_pr\ or\ v = \frac{X}{t_{2}-t_{1}} .......... 4\f] \n
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//! If \f[ \frac{max}{base}\ freq = 10kHz => 10kHz = \frac{(4/2)}{T} = \
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\frac{4}{2T} \f] \n
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//! where,
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//! - 4 = QCAPCTL [UPPS] (Unit timeout - once every 4 edges)
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//! - 2 = divide by 2 because QPOSCNT counts 2 edges per cycle
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//! (rising and falling)
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//! - T = time in seconds
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//! = \f$ \frac{t_{2}-t_{1}}{(150MHz/128)}, t_{2}-t_{1} \f$ =
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//! # of QCAPCLK cycles,
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//! \n and \f$ 1\ QCAPCLK\ cycle = \frac{1}{(150MHz/128)} = QCPRDLAT \f$
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//!
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//! So: \f[ 10 kHz = 4*\frac{(150MHz/128)}{2*(t_{2}-t_{1})} \f] \n
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//! \f[ t_{2}-t_{1} = 4*\frac{(150MHz/128)}{10kHz*2} = \
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\frac{(150MHz/128)}{((2*10KHz)/4)} .......... 5\f] \n
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//! \f[ = 234\ QCAPCLK\ cycles = maximum (t_{2}-t_{1}) = freqScaler\_pr \f]
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//! Divide both sides by \f$ (t_{2}-t_{1}) \f$, and:\n
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//! \f[ 1 = \frac{234}{t_{2}-t_{1}} = \
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\frac{(150MHz/128)/((2*10KHz)/4)}{t_{2}-t_{1}} \f]\n
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//! Because \f$ (t_{2}-t_{1}) < 234 (max) \f$,
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//! \f$ \frac{234}{t_{2}-t_{1}} < 1 \f$ for all frequencies less than max \n
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//! \f[ freq\_pr = \frac{234}{t_{2}-t_{1}}\ or\ \
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\frac{(150MHz/128)/((2*10KHz)/4)}{t_{2}-t_{1}} .......... 6\f] \n
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//! Now within velocity limits, to get back to original velocity equation,
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//! Equation 1, multiply Equation 6 by 10 kHz: \n
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//! \f[ freqhz\_fr(or\ velocity) = \
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10kHz*\frac{(150MHz/128)/((2*10KHz)/4)}{t_{2}-t_{1}}\f]\n
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//! \f[ = \frac{(150MHz/128)*4}{2*(t_{2}-t_{1})} \f]\n
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//! or
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//! \f[ \frac{4}{2*(t_{2}-t_{1})*(QCPRDLAT)} .......... final\ equation\f] \n
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//!
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//! For 100 MHz Operation:
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//!
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//! The same calculations as above are performed, but with 100 MHz
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//! instead of 150MHz when calculating freqhz_pr, and at UPPS of 8
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//! instead of 4. The value for freqScaler_pr becomes:
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//! (100MHz/128)/(2*10kHz/8) = 313
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//!
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//! More detailed calculation results can be found in the Example_freqcal.xls
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//! spreadsheet included in the example folder.
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//
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//###########################################################################
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// $TI Release: $
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// $Release Date: $
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// $Copyright:
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// Copyright (C) 2009-2023 Texas Instruments Incorporated - http://www.ti.com/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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//
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// Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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//
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// Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the
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// distribution.
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//
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// Neither the name of Texas Instruments Incorporated nor the names of
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// its contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// $
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//###########################################################################
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//
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// Included Files
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//
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#include "DSP28x_Project.h" // Device Headerfile and Examples Include File
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#include "Example_freqcal.h" // Example specific include file
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//
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// FREQCAL_Init -
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//
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void
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FREQCAL_Init(void)
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{
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#if (CPU_FRQ_150MHZ)
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EQep1Regs.QUPRD=1500000; // Unit Timer for 100Hz at 150MHz SYSCLKOUT
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#endif
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#if (CPU_FRQ_100MHZ)
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EQep1Regs.QUPRD=1000000; // Unit Timer for 100Hz at 100MHz SYSCLKOUT
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#endif
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EQep1Regs.QDECCTL.bit.QSRC=2; // Up count mode (freq. measurement)
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EQep1Regs.QDECCTL.bit.XCR=0;
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EQep1Regs.QEPCTL.bit.FREE_SOFT=2;
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EQep1Regs.QEPCTL.bit.PCRM=00; // QPOSCNT reset on index evnt
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EQep1Regs.QEPCTL.bit.UTE=1; // Unit Timer Enable
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EQep1Regs.QEPCTL.bit.QCLM=1; // Latch on unit time out
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EQep1Regs.QPOSMAX=0xffffffff;
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EQep1Regs.QEPCTL.bit.QPEN=1; // QEP enable
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#if (CPU_FRQ_150MHZ)
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EQep1Regs.QCAPCTL.bit.UPPS=2; // 1/4 for unit position at 150MHz SYSCLKOUT
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#endif
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#if (CPU_FRQ_100MHZ)
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EQep1Regs.QCAPCTL.bit.UPPS=3; // 1/8 for unit position at 100MHz SYSCLKOUT
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#endif
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EQep1Regs.QCAPCTL.bit.CCPS=7; // 1/128 for CAP clock
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EQep1Regs.QCAPCTL.bit.CEN=1; // QEP Capture Enable
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}
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//
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// FREQCAL_Calc -
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//
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void
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FREQCAL_Calc(FREQCAL *p)
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{
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unsigned long tmp;
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_iq newp,oldp;
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//
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// Freq Calculation using QEP position counter
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// Check unit Time out-event for speed calculation
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//
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//
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// Unit Timer is configured for 100Hz in INIT function
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//
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//
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// For a more detailed explanation of the calculation, read
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// the description at the top of this file
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//
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if(EQep1Regs.QFLG.bit.UTO==1) // Unit Timeout event
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{
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//
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// Differentiator
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//
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newp=EQep1Regs.QPOSLAT; // Latched POSCNT value
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oldp=p->oldpos;
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if (newp>oldp)
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{
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tmp = newp - oldp; // x2-x1 in v=(x2-x1)/T equation
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}
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else
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{
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tmp = (0xFFFFFFFF-oldp)+newp;
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}
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//
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// p->freq_fr = (x2-x1)/(T*10KHz)
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//
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p->freq_fr = _IQdiv(tmp,p->freqScaler_fr);
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tmp=p->freq_fr;
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if (tmp>=_IQ(1))
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{
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p->freq_fr = _IQ(1);
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}
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else
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{
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p->freq_fr = tmp;
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}
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//
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// Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q
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// p->freqhz_fr = (p->freq_fr)*10kHz = (x2-x1)/T
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//
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p->freqhz_fr = _IQmpy(p->BaseFreq,p->freq_fr);
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//
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// Update position counter
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//
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p->oldpos = newp;
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EQep1Regs.QCLR.bit.UTO=1; // Clear interrupt flag
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}
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//
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// Freq Calculation using QEP capture counter
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//
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if(EQep1Regs.QEPSTS.bit.UPEVNT==1) // Unit Position Event
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{
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if(EQep1Regs.QEPSTS.bit.COEF==0) // No Capture overflow
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{
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tmp=(unsigned long)EQep1Regs.QCPRDLAT;
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}
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else // Capture overflow, saturate the result
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{
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tmp=0xFFFF;
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}
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//
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// p->freq_pr = X/[(t2-t1)*10KHz]
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//
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p->freq_pr = _IQdiv(p->freqScaler_pr,tmp);
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tmp=p->freq_pr;
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if (tmp>_IQ(1))
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{
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p->freq_pr = _IQ(1);
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}
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else
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{
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p->freq_pr = tmp;
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}
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//
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// Q0 = Q0*GLOBAL_Q => _IQXmpy(), X = GLOBAL_Q
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// p->freqhz_pr =( p->freq_pr)*10kHz = X/(t2-t1)
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//
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p->freqhz_pr = _IQmpy(p->BaseFreq,p->freq_pr);
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//
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// Clear Unit position event flag
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// Clear overflow error flag
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//
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EQep1Regs.QEPSTS.all=0x88;
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}
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}
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//
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// End of File
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//
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