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Okay I've tossed this together into a stand alone program. I messed around with your code/my code quiet a bit, so I'll give you the simplist version with just your code. I was hoping PWM0 or PWM1 would produce the signal for IC3. ACCD would hold the a count of time. I get 0000 in ACCD when I put a breakpoint in NOP. I don't understand why this isn't working! Thanks for the continued help. ORG RAM_START bset TSCR1,%10000000 ;TEN=1 - Enable timer bset TIE,%1000 ;Enable input capture 3 bset TFLG1,%1000 ;Clear input capture 3 interrupt movb #%10000000,TCTL4 ;Capture on Falling edge BSET DDRP,%00000011 movb #%00000000,PWME ;All channels disabled movb #%00000000,PWMPOL ;Low during duty cycle movb #%00000000,PWMCLK ;Clock SA & Clock SB movb #%01110111,PWMPRCLK ;Clock A = Bus Clock / 128 movb #%00000000,PWMCAE ;channels in Left Aligned Output Mode movb #%00001100,PWMCTL ;No concatenation movb #%00000000,PWMSCLA ;Clock SA = Clock A / ( 2 * 256) movb #%11111111,PWMPER0 movb #%11111000,PWMDTY0 bset PWME,%00000011 ;enable PWM0 and PWM1 ldd TC3 movb #%00001000,TFLG1 ;Clear input capture 3 interrupt NOP NOP NOP --- In , "zeta_alpha2002 <zeta_alpha2002@y...>" <zeta_alpha2002@y...> wrote: > This one works for me. I used PWM1 output and IC3 to measure PWM1. > I got 1/(32640 counts * 125E-9)=~245hz. I verified result with > frequency counter. > > Var2 is the result of the difference between 1st and 2nd capture of > falling edges. Note that if the frequency is doubled then there > would be a problem with overflow, so some readjustment is required > for your apps. Hope this one would help - good luck. > > bset TSCR1,%10000000 ;TEN=1 - Enable timer > bset TIE,%1000 ;Enable input capture 3 > bset TFLG1,%1000 ;Clear input capture 3 > interrupt > movb #%10000000,TCTL4 ;Capture on Falling edge > > clr capFlag > > PWMInit > bset DDRP,PWME0+PWME1 ;Bit 1,0 = o/p > > movb #%00000000, PWME ;All channels disabled > movb #%00000000, PWMPOL ;Low during duty cycle > movb #%00000000, PWMCLK ;Clock SA & Clock SB > movb #%01110111, PWMPRCLK ;Clock A = Bus Clock / 128, > Clock B = Bus Clock / 128 > movb #%00000000, PWMCAE ;All channels operate in Left > Aligned Output Mode > movb #%00001100, PWMCTL ;No concatenation > movb #%00000000, PWMSCLA ;Clock SA = Clock A / ( 2 * > 256) > movb #%00000000, PWMSCLB ;Clock SB = Clock B / ( 2 * > 256) > > movb #%11111111, PWMPER0 > movb #%11111111, PWMPER1 > > movb #%11111000, PWMDTY0 > movb #%10000000, PWMDTY1 > > bset PWME,PWME0+PWME1 ;enable PWM0 and PWM1 > > rts > > ;------------------------------- -- > --------- > IC3Int > ldd TC3 > pshd ;Save momentarily > > ldaa capFlag ;Check if 1st or 2nd capture > bne SecondCap ;If flag is set then it is > 2nd falling edge > > puld > std Var1 ;1st Capture > movb #1,capFlag > bra ICex ;Wait until next capture > > SecondCap > puld > subd Var1 ;Subtract from 1st Capture > std Var2 ;Result in Var2 > clr capFlag > > ICex > movb #%00001000,TFLG1 ;Clear input capture 3 > interrupt > rti > --- In , "jeffguilfoil <jeffguilfoil@y...>" > <jeffguilfoil@y...> wrote: > > --- In , "zeta_alpha2002 > <zeta_alpha2002@y...>" > > <zeta_alpha2002@y...> wrote: > > > > ECT. I do not understand why it is not working. I've got a > > HCS12 > > > > > > Your PWM regs are not initialized correctly, specially the > > PWMPER0. > > > This one works for me, change the clock for higher freq. > > > > Thanks for the reply. > > > > I tried the settings you suggested, it's still not working. If I > do > > 62500hz/256 = 122hz output (PWMCLK=$03 SA clock, PWMPRCLK=$0F SA = > > 8mhz/128, PWMSCLA=$00 SAb500hz/2, PWMPER0=$0F SA2500/256) and > > select input capture of 8mhz/256 = 32500hz sample. The 16-bit > input > > capture register never fills and the timer always overflows. > > > > I've tested the PWM output on it's slowest setting with a > multimeter > > and it is working. Feeding the PWM output into the input capture > pin > > always results in timer overflow. > > > > Any ideas? > > Thanks again, > > Jeff |
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Measuring PWM /w input capture ECT
Started by ●December 26, 2002
Reply by ●January 2, 20032003-01-02
Reply by ●January 2, 20032003-01-02
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> ORG RAM_START Wait a minute...Are your testing the codes in RAM? The settings I wrote are using interrupts, so if your testing it in RAM how is IC3 interrupt being vectored? I was just curious why you were having no luck so I wrote quickie code to see why not and burn it into flash. Cannot seem to duplicate your problem. I could only see an overflow if the frequency is less than 245/22Hz because the counts I was getting was 32640. If you double 32640 then it would be 65280 which is close to $FFFF. I used an Adapt9S12DP256 with 16Mhz crystal. Pll not enabled. Email me at and I will give you the routine I used. You will have to burn it into flash though. The results is dump out of SCI0 at 9600,8,N,1. Open a terminal window and press R for the program to start dumping the result. Are you perchance using D-BUG to test your code? If you are then change the value at address $3E68 to the value of the IC3 interrupt address routine. |
Reply by ●January 3, 20032003-01-03
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Jeff, I have a calculation of duty cycle using an A4 with and ADXL202 accelerometer device. These devices have a fixed period variable duty output relative to applied force, maybe this code will help: /* tc3 capture state values */ #define CAP_VALID ((char) (0x00)) /* made measurement, take it */ #define CAP_INVALID ((char) (0xff)) /* making measurement, do not disturb */ #define CAP_NON ((char) (0x01)) /* no measurement made */ #define CAP_NOSIG ((char) (0x02)) /* no signal received */ struct Capture { unsigned int lead; unsigned int period; unsigned int high; char result; } Accel; /* int_tc3() -- here each time edge capture from accelerometer (vert) occurs */ void int_tc3(void) { if ((PORTT & 0x08) != 0) { /* * Input bit is high */ Accel.period = TC3 - Accel.lead; Accel.result = CAP_VALID; /* valid */ /* set leading edge point to current capture */ Accel.lead = TC3; } else /* * Input bit is low... */ /* we know leading edge point, calculate high time. Wait for next capture for result */ Accel.high = TC3 - Accel.lead; Accel.result = CAP_INVALID; /* invalid */ /* reset the interrupt flag */ TFLG1=0x08; } Your main routine can read the value for duty using the this typical call to the following routine: (long)duty=dutyval(Accel.high, Accel.period, 10000) /* dutyval -- calculates the duty cycle (high/period) scaled by places */ long dutyval(high, period, places) int high; int period; int places; { long h; long p; long r; h=(long) high * (long) places; p=(long) period; r=h/p; if (r < 0L || r > (long) (100*places)) return (-1); else return (r); } The timer initialization will typically need: CLKCTL = 0x00; /* timer MCLK=4MHz */ TIOS = 0x00; /* All input captures */ TSCR = 0x80; /* enable timer */ TCTL4 = 0xc0; /* Timer 3 input capture, both edges */ TMSK1 = 0x08; /* TC3 enabled */ TMSK2 = 0x81; /* TOI enabled, prescale div 2 */ Hope this helps, Jonathan Masters ----- Original Message ----- From: <> To: <> Sent: Friday, January 03, 2003 10:17 AM Subject: [68HC12] Re: Measuring PWM /w input capture ECT (Please help) > I don't have code working yet, that's why I posted here. :) Judging > from the way the CAS signal looks I would guess that it's mag pickup > or something. A pulse is created every crankshaft rotation figure > 7000RPM ~= 117hz. I'm reluctant to do the A/D method because my > sample periods will be pretty short and I think doing it with assured > accuracy is pretty much the input capture method. I'll give it a try > if/when I rule out the input capture. Input capture should work, but > I can't get it to! I starting to feel like a real idiot. :) > > --- In , "Stephen Mac Neil" <macneil@d...> > wrote: > > Do you have any code that can do that, I would be very interested > in getting > > the sub routine and examining that. Is that like a mag pickup input > to the > > unit, this crank sensor. What would be the sampling rate of the a/d > what is > > the frequency ranges of the input signal? I am working on something > similar > > but don't know if its the same or not. > > > > Stephen Mac Neil > > -----Original Message----- > > From: jeffguilfoil <jeffguilfoil@y...> > > [mailto:jeffguilfoil@y...] > > Sent: Tuesday, December 31, 2002 7:12 PM > > To: > > Subject: [68HC12] Re: Measuring PWM /w input capture ECT (Please > help) > > > > > > --- In , BobGardner@a... wrote: > > > Hi Jeff. Why not just run the pwm into an rc lo pass filter, and > > run that > > > into an a/d input? The a/d reads the avg voltage of the pwn > > waveform from the > > > cap. This is exactly what you want, right? > > > > > > > Thanks for the reply. > > > > Yes, I suppose the results using your technique are what I'm > looking > > for. I will be using a signal from a automobile crank angle > sensor, > > so the length of the highs changes perportionally with the length > of > > the lows. Do you see any problems with your suggested approach? > The > > only issue I see is what if the start of the sample doesn't land > on > > the same part of the pulse wave and the sample time is rather > short > > the value might quiet different. Thoughts? > > > > Jeff > > > > > > > > > > > > > > > > -------------------- > > > > > > > > ">http://docs.yahoo.com/info/terms/ |
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Reply by ●January 3, 20032003-01-03
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I'm not exactly sure why, but I got my code to work! Sincere thanks to zeta_alpha2002, Jonathan Masters and Bob Gardner for the help. |
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Reply by ●January 7, 20032003-01-07
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Are you sure you want to measure PWM? A crank or cam sensor will have a constant pulse width, the frequency varies with engine RPM. Andrei |
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Reply by ●January 8, 20032003-01-08
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I thought it would be a input capture averaging the frequency of a couple
of samples to determine the frequency of the engine at any particular time. Stephen -----Original Message----- From: Andrei Chichak [mailto:] Sent: Tuesday, January 07, 2003 6:07 PM To: Subject: Re: [68HC12] Re: Measuring PWM /w input capture ECT - Got it working! Are you sure you want to measure PWM? A crank or cam sensor will have a constant pulse width, the frequency varies with engine RPM. Andrei -------------------- |
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Reply by ●January 17, 20032003-01-17
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I appologize for the late reply. I'm measuring the time between when the pulse goes high. ie. |-|_| That time changes when the RPM changed on the CAS. Also, the peak |- | and vally |_| time changes perportionally with RPM. I took an Oscilloscope to a CAS to be 100% sure that occurs. I hope I'm not making an incredibly daft mistake, so please correct me if I'm wrong. :) --- In , Andrei Chichak <acpmiedm@t...> wrote: > Are you sure you want to measure PWM? A crank or cam sensor will have a > constant pulse width, the frequency varies with engine RPM. > > Andrei |
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Reply by ●January 20, 20032003-01-20
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I'm just wondering why you would do this type of timing rather than
doing an RPM count and calculate the times? If you are trying to determine the positions to synchronize injection or ignition pulses, I'm not sure you are on the right track at all. There are quite a few web sites around dealing with injection/ignition that you might want to look at. Start at www.diy-efi.org. Motorola, I seem to remember, has an app note on doing injection using their modular counter time module (CTM) if my memory is not failing. THere has been articles published by Circuit Cellar www.circuitcellar.com that have these systems well described, and Al Lipper has a couple of systems written up that use 8051s. Andrei At 02:24 AM 1/18/2003 +0000, you wrote: >I appologize for the late reply. > >I'm measuring the time between when the pulse goes high. ie. |-|_| >That time changes when the RPM changed on the CAS. Also, the peak |- >| and vally |_| time changes perportionally with RPM. I took an >Oscilloscope to a CAS to be 100% sure that occurs. > >I hope I'm not making an incredibly daft mistake, so please correct >me if I'm wrong. :) > >--- In , Andrei Chichak <acpmiedm@t...> wrote: > > Are you sure you want to measure PWM? A crank or cam sensor will >have a > > constant pulse width, the frequency varies with engine RPM. > > > > Andrei > >-------------------- > >">http://docs.yahoo.com/info/terms/ |
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Reply by ●January 20, 20032003-01-20
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"modular counter time module (CTM)" You are probably thinking of the TPU (Time Processing Unit) present on all MC68332 MCUs and many other Motorola MCUs of the modular MCU family. These little jewels have specific timer functions built in that detect crankshaft position and calculate the firing angle for ignition and fuel injection timing. The '332 was designed specifically for engine management, but is also a wonderful little general purpose MCU with lots and lots of horsepower. Bob Smith --- Avoid computer viruses, Practice safe hex --- -- Specializing in small, cost effective embedded control systems -- Robert L. (Bob) Smith Smith Machine Works, Inc. 9900 Lumlay Road Richmond, VA 23236 804/745-1065 ----- Original Message ----- From: "Andrei Chichak" <> To: <> Sent: Monday, January 20, 2003 4:53 PM Subject: Re: [68HC12] Re: Measuring PWM /w input capture ECT - Got it working! > I'm just wondering why you would do this type of timing rather than doing > an RPM count and calculate the times? > > If you are trying to determine the positions to synchronize injection or > ignition pulses, I'm not sure you are on the right track at all. There are > quite a few web sites around dealing with injection/ignition that you might > want to look at. Start at www.diy-efi.org. Motorola, I seem to remember, > has an app note on doing injection using their modular counter time module > (CTM) if my memory is not failing. THere has been articles published by > Circuit Cellar www.circuitcellar.com that have these systems well > described, and Al Lipper has a couple of systems written up that use 8051s. > > Andrei > > At 02:24 AM 1/18/2003 +0000, you wrote: > >I appologize for the late reply. > > > >I'm measuring the time between when the pulse goes high. ie. |-|_| > >That time changes when the RPM changed on the CAS. Also, the peak |- > >| and vally |_| time changes perportionally with RPM. I took an > >Oscilloscope to a CAS to be 100% sure that occurs. > > > >I hope I'm not making an incredibly daft mistake, so please correct > >me if I'm wrong. :) > > > >--- In , Andrei Chichak <acpmiedm@t...> wrote: > > > Are you sure you want to measure PWM? A crank or cam sensor will > >have a > > > constant pulse width, the frequency varies with engine RPM. > > > > > > Andrei > > > > > > > >-------------------- > > > > > > > >">http://docs.yahoo.com/info/terms/ > > -------------------- > > ">http://docs.yahoo.com/info/terms/ > |
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Reply by ●January 21, 20032003-01-21
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I have a couple of the EFI332 boards assembled and use '332s in my
daily job, but I have seen app notes from a couple of manufacturers on doing injection/ignition without using the TPU. One was from Seimens and the other was for one of Moto's smaller processors (not the HC16 w/TPU), but do you think I can find it??? NOOOOooo.. http://www.infineon.com/cmc_upload/migrated_files/document_files/Application_Notes/ap163502.pdf Motorola also has some app notes for the HC08 as well. Andrei At 10:12 PM 1/20/2003 -0500, you wrote: >"modular counter time module (CTM)" > >You are probably thinking of the TPU (Time Processing Unit) present on all >MC68332 MCUs and many other Motorola MCUs of the modular MCU family. > >These little jewels have specific timer functions built in that detect >crankshaft position and calculate the firing angle for ignition and fuel >injection timing. > >The '332 was designed specifically for engine management, but is also a >wonderful little general purpose MCU with lots and lots of horsepower. > > Bob Smith > >--- Avoid computer viruses, Practice safe hex --- > >-- Specializing in small, cost effective > embedded control systems -- >Robert L. (Bob) Smith >Smith Machine Works, Inc. >9900 Lumlay Road >Richmond, VA 23236 804/745-1065 > >----- Original Message ----- >From: "Andrei Chichak" <> >To: <> >Sent: Monday, January 20, 2003 4:53 PM >Subject: Re: [68HC12] Re: Measuring PWM /w input capture ECT - Got it >working! > > I'm just wondering why you would do this type of timing rather than doing > > an RPM count and calculate the times? > > > > If you are trying to determine the positions to synchronize injection or > > ignition pulses, I'm not sure you are on the right track at all. There are > > quite a few web sites around dealing with injection/ignition that you >might > > want to look at. Start at www.diy-efi.org. Motorola, I seem to remember, > > has an app note on doing injection using their modular counter time module > > (CTM) if my memory is not failing. THere has been articles published by > > Circuit Cellar www.circuitcellar.com that have these systems well > > described, and Al Lipper has a couple of systems written up that use >8051s. > > > > Andrei > > > > At 02:24 AM 1/18/2003 +0000, you wrote: > > >I appologize for the late reply. > > > > > >I'm measuring the time between when the pulse goes high. ie. |-|_| > > >That time changes when the RPM changed on the CAS. Also, the peak |- > > >| and vally |_| time changes perportionally with RPM. I took an > > >Oscilloscope to a CAS to be 100% sure that occurs. > > > > > >I hope I'm not making an incredibly daft mistake, so please correct > > >me if I'm wrong. :) > > > > > >--- In , Andrei Chichak <acpmiedm@t...> wrote: > > > > Are you sure you want to measure PWM? A crank or cam sensor will > > >have a > > > > constant pulse width, the frequency varies with engine RPM. > > > > > > > > Andrei > > > > > > > > > > > >-------------------- > > > > > > > > > > > >">http://docs.yahoo.com/info/terms/ > > > > > > > > -------------------- > > > > > > > > ">http://docs.yahoo.com/info/terms/ > > > > > > >-------------------- > >">http://docs.yahoo.com/info/terms/ |
