6 HPWM signal generation with PIC18F4431


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  1. #1

    Lightbulb 6 HPWM signal generation with PIC18F4431

    Hi there,

    I'm currently making a 3-phase variable frequency drive.
    I'm using the PIC18F4431 (5V - 40 pins - 40MHz), who's perfect for motor control (8 hardware PWM outputs).

    Datasheet : http://ww1.microchip.com/downloads/e...Doc/39616d.pdf

    I like to generate 3 high-side hardware PWM (HU, HV, HW) and 3 low-side hardware PWM (LU, LV, LW - same as HU, HV, HW but inverted with a low deadtime) for fed my high and low-side IGBTs.
    I would like a PWM carrier frequency between 2 and 20kHz (approx.)

    Picbasic Pro seems to use CCP1 and CCP2 modules with "HPWM" command, but I get only 2 HPWM outputs.
    I have no idea how to use these hardware PWM modules on my PIC.

    Thanks for your help.
    Last edited by pxidr84; - 10th February 2011 at 20:27.

  2. #2
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    Default Re: 6 HPWM signal generation with PIC18F4431

    Hi,
    PBP (the HPWM command) only suports PWM thru the standard CCP modules, you'll have to set up the PWM registers manually. A quick search for 18F4431 on the forum brings up a couple of threads, this one for example, contains some sample code from Bruce which may serve as a starting point.

  3. #3

    Default Re: 6 HPWM signal generation with PIC18F4431

    Quote Originally Posted by HenrikOlsson View Post
    Hi,
    PBP (the HPWM command) only suports PWM thru the standard CCP modules, you'll have to set up the PWM registers manually. A quick search for 18F4431 on the forum brings up a couple of threads, this one for example, contains some sample code from Bruce which may serve as a starting point.
    Thanks, I will take a look.

  4. #4

    Default Re: 6 HPWM signal generation with PIC18F4431

    Okay, I've a little bit modified the Bruce's program.
    It runs well in ISIS Proteus with my defined duty cycles, and all of the 6 PWM outputs works.

    But there is a little problem :


    As you can see, U and W phases are working properly, but not the V phase (the low-side PWM is not inverted like the others).

    Here's my modified code :
    Code:
    DEFINE LOADER_USED 1
    DEFINE OSC 20
        
        ' At 20MHz, to figure a PWM frequency of 19.455kHz
        ' TPWM = time period of PWM frequency
        ' PTPER = 12-bit period register PTPERL and PTPERH
        ' PTMRPS = PWM time base prescaler
        ' 
        '        (PTPER+1)*PTMRPS  257
        ' TPWM = ----------------  =  ------------ = 0.0000514 
        '             Fosc/4            5000000
        '
        ' Frequency = 1/TPWM = 1/0.0000514 = 19.455kHz
        '
        ' PWM resolution (bits resolution for duty cycle)
        '
        '              log(20MHz/19.455kHz)    3.01
        ' Resolution = ------------------ = ----------- = 10 bits
        '                    .301              .301
          
        ' so we'll need a word sized var for Duty
    uduty VAR WORD
    vduty VAR WORD
    wduty VAR WORD
       
        PORTB = 0               ' clear port latch
        TRISB = %11000000       ' PWM0,1,2,3,4,5 outputs
        
        TRISC = 2         ' RC1 = FLTA input (ground RC1 to halt PWM)
                                ' RC1 should be pulled high for normal PWM operation
                                ' when fault A is enabled.
        ' PCPWM init
        DTCON = %00000101       ' ~500nS dead-time (for complementary outputs only)
        PTCON0 = %00000100      ' 1:1 postscale, Fosc/4 1:1 prescale, free running mode
                                ' PTCON0 = %00000100 would give 19.45kHz/4
        PTPERL = 0              ' 
        PTPERH = 1              ' PTPER = $0100 or 256d for ~19.45kHz
    	
        ' PWM4,5 independent, PWM0,1,2,3 complementary
        PWMCON0 = %01010100     ' PWM[5:0] outputs enabled
        PWMCON1 = 1             ' updates enabled, overrides sync w/timebase
        PTCON1 = %10000000      ' PWM time base is ON, counts up
        FLTCONFIG = %00000011   ' enable fault A, cycle-by-cycle mode
    
    
    'Phases duty test
    uduty = 800              ' ~50%
    vduty = 500
    wduty = 300
            
    pwmlp: ' PWM update loop
    
    'PWM U phase 
    PDC0L = uduty.LowByte
    PDC0H = uduty.HighByte
    
    'PWM V phase
    PDC1L = vduty.LowByte
    PDC1H = vduty.HighByte
    
    'PWM W phase  
    PDC2L = wduty.LowByte
    PDC2H = wduty.HighByte
    
    goto pwmlp
    Thanks in advance for any advice.
    Last edited by pxidr84; - 11th February 2011 at 23:38.

  5. #5
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    Default Re: 6 HPWM signal generation with PIC18F4431

    Hi,
    Are you sure it's not the W-phase output that isn't complementary?

    Look at the PWMCON0 register, you have it set to %01010100 which means that PWM0 and PWM1 is in complentary mode while PWM2 (the W-phase according to your code) is in independant mode.

    /Henrik.

  6. #6

    Default Re: 6 HPWM signal generation with PIC18F4431

    Quote Originally Posted by HenrikOlsson View Post
    Hi,
    Are you sure it's not the W-phase output that isn't complementary?

    Look at the PWMCON0 register, you have it set to %01010100 which means that PWM0 and PWM1 is in complentary mode while PWM2 (the W-phase according to your code) is in independant mode.

    /Henrik.
    Thanks a lot, you guided me on the right way.
    I've read the datasheet, and especially the "PWMCON0" register description. I've modified the value to PWMCON0 = %01000000, and now the 3 phases are working very well (the low-side V phase is now inverted properly).

    Now, I've to modify the duty according to a sinus function. I think about it.

  7. #7

    Default Re: 6 HPWM signal generation with PIC18F4431

    A last question : I've doubts about the duty cycle. What's the exact range of the duty cycle?

    If I define a duty cycle between 0-10, the simulator oscilloscope gives me weird things (the inverted signal "jumps")...
    If I define a duty cycle above 1023, same thing...

    The code used :
    Code:
        ' At 20MHz, to figure a PWM frequency of 19.455kHz
        ' TPWM = time period of PWM frequency
        ' PTPER = 12-bit period register PTPERL and PTPERH
        ' PTMRPS = PWM time base prescaler
        ' 
        '        (PTPER+1)*PTMRPS  257
        ' TPWM = ----------------  =  ------------ = 0.0000514 
        '             Fosc/4            5000000
        '
        ' Frequency = 1/TPWM = 1/0.0000514 = 19.455kHz
        '
        ' PWM resolution (bits resolution for duty cycle)
        '
        '              log(20MHz/19.455kHz)    3.01
        ' Resolution = ------------------ = ----------- = 10 bits
        '                    .301              .301
     
    'PIC initialization
    DEFINE LOADER_USED 1
    DEFINE OSC 40      
    
    'Port registers configuration
    PORTB = 0               ' Clear ports
    TRISB = %11000000       ' PWM 0,1,2,3,4,5 outputs
    TRISC = 2               ' RC1 = FLTA input (ground RC1 to halt PWM), pull-up resistor on RC1
                                
    'PCPWM registers configuration
    DTCON = %00001010       ' Deadtime (500ns)
    PTCON0 = %00000100      ' 1:1 postscale, Fosc/4 1:1 prescale, free running mode
    PTCON1 = %10000000      ' PWM time base is ON, counts up, 19.45kHz/4
    PTPERL = 0              ' PWM low-side
    PTPERH = 1              ' PWM high-side
    	
    'PWM registers configuration
    PWMCON0 = %01000000     'PWM 0,1,2,3,4,5 set in pair mode
    PWMCON1 = %00000001     'PWM timer sync configuration
    FLTCONFIG = %00000011   'Fault configuration
    
    'U, V and W duty variables
    uduty VAR WORD
    vduty VAR WORD
    wduty VAR WORD
    
    'Phases duty
    uduty = 1         
    vduty = 1000
    wduty = 1000
            
    pwmlp: ' PWM update loop
    
    'PWM U phase 
    PDC0L = uduty.LOWbyte
    PDC0H = Uduty.HIGHByte
    
    'PWM V phase
    PDC1L = vduty.LOWbyte
    PDC1H = vduty.HIGHByte
    
    'PWM W phase  
    PDC2L = wduty.LOWbyte
    PDC2H = wduty.HIGHByte
    
    goto pwmlp

  8. #8
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    Default Re: 6 HPWM signal generation with PIC18F4431

    Hi,
    The available resolution depends on the actual PWM frequency, you can see in the code how Bruce has calculated it for you. If you haven't changed the code the resolution is 10 bits (0-1023).

    The PCPWM module have a configurable dead-time generator which inserts a deadtime between turning off the upper switch and turning on the lower switch. When aproaching the "ends" of the available resolution this can distort the output waveform and I suspect that is what you're seeing.

    If you don't need deadtime you can turn it off. If you do need deadtime you should make sure that the dutycyle never aproaches the values where you're starting to see distortion. You usually can't use extreme dutycycles anyway due to the MOSFET/IGBT highside drivers need to refresh its bootstrap capacitor charge.

  9. #9

    Default Re: 6 HPWM signal generation with PIC18F4431

    Okay, the code is now capable to calculate 3 sine waves (one for each phase).

    I can modify the frequency (by increasing or decreasing freqdiv), but I've difficulties to set a phase angle (0-120-240 for U, V and W respectively) and I've difficulties to set a sinus amplitude (for exemple, if I want a 0-50% dutycycle, I will write uduty=uduty*0.5, but PBP does not support float maths).

    Thanks for your help. I use Darrel Taylor's interrupt system for sine-wave generation loop.

    Code:
    'PIC initialization
    DEFINE LOADER_USED 1
    DEFINE OSC 40      
    
    
    'DT interrupt system include
    INCLUDE "DT_INTS-18.bas"     ' Base Interrupt System
    INCLUDE "ReEnterPBP-18.bas"  ' Include if using PBP interrupts
    
    
    'PWM calculation variables
    uduty VAR WORD     'U phase duty
    vduty VAR WORD     'V phase duty
    wduty VAR WORD     'W phase duty
    t VAR byte         'Incremental value
    
    
    'Inverter U/F variables
    freqdiv var WORD   'Frequency diviser
    FREQdiv=0          'Range : 0-65535
    
    
    'Port registers configuration
    PORTB=%0          ' Clear ports
    TRISB=%11000000   ' PWM 0,1,2,3,4,5 outputs
    
                                
    'PCPWM registers configuration
    DTCON=%110        ' Deadtime (600ns)
    PTCON0=%100       ' 1:1 postscale, Fosc/4 1:1 prescale, free running mode
    PTCON1=%10000000  ' PWM time base is ON, counts up, 19.45kHz/4
    PTPERL=%0         ' PWM low-side
    PTPERH=%1         ' PWM high-side
    
    	
    'PWM registers configuration
    PWMCON0=%1000000  'PWM 0,1,2,3,4,5 set in pair mode
    PWMCON1=%1        'PWM timer sync configuration
    
    
    'Interrupt processor
    ASM
    INT_LIST  macro    ; IntSource, Label, Type, ResetFlag
            INT_Handler   TMR1_INT,  _pwmint,   PBP,  yes
        endm
        INT_CREATE     ; Creates the interrupt processor
    ENDASM
    
    
    'Timer configuration
    T1CON=%10000001            ; Prescaler = 1:1, TMR1ON, 16-bit counter
    @ INT_ENABLE  TMR1_INT     ; Enable Timer 1 interrupts
    
    
    'Main loop
    mainlp:
    
        pause 1000
    
    goto mainlp
    
    'PWM calculation and update interrupt
    pwmint:
    t=0
        
        for T=0 to 255 step 1
    
        'Frequency diviser
        pauseus freqdiv
    
        'PWM U phase calculation
        uduty=((sin(t)+128)*4)  
          
        'PWM V phase calculation
        vduty=((sin(t)+128)*4)
        
        'PWM W phase calculation
        wduty=((sin(t)+128)*4)
    
        'PWM U phase update
        PDC0L=uduty.LOWbyte
        PDC0H=Uduty.HIGHByte
    
        'PWM V phase update
        PDC1L=vduty.LOWbyte
        PDC1H=vduty.HIGHByte
    
        'PWM W phase update
        PDC2L=wduty.LOWbyte
        PDC2H=wduty.HIGHByte
    
        next t
    
    @ INT_RETURN
    Last edited by pxidr84; - 19th February 2011 at 11:13.

  10. #10
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    Default Re: 6 HPWM signal generation with PIC18F4431

    Hi,
    How about:
    Code:
    'PWM U phase calculation
    uduty=((sin(t)+128)*4)  
          
    'PWM V phase calculation
    vduty=((sin(t+85)+128)*4)
        
     'PWM W phase calculation
    wduty=((sin(t+170)+128)*4
    Name:  3-phase sin.jpg
Views: 8038
Size:  76.0 KB

    It's true that you can't mutliply by 0.5 but you can divide by 2. You can also use the ** operator to multiply by units of 1/65536 so instead of doing x=y*0.72 you do x=y**47186 (where 47186 comes from 65536*0.72)

    /Henrik.

  11. #11

    Default Re: 6 HPWM signal generation with PIC18F4431

    Quote Originally Posted by HenrikOlsson View Post
    Hi,
    How about:
    Code:
    'PWM U phase calculation
    uduty=((sin(t)+128)*4)  
          
    'PWM V phase calculation
    vduty=((sin(t+85)+128)*4)
        
     'PWM W phase calculation
    wduty=((sin(t+170)+128)*4
    Attachment 5180

    It's true that you can't mutliply by 0.5 but you can divide by 2. You can also use the ** operator to multiply by units of 1/65536 so instead of doing x=y*0.72 you do x=y**47186 (where 47186 comes from 65536*0.72)

    /Henrik.
    Thanks a lot for your tips
    Just a question : what simulator are you using ? (because my ISIS Proteus gives me very weird results):



    It's your code with angle phase offsets...
    Last edited by pxidr84; - 19th February 2011 at 13:02.

  12. #12
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    Default Re: 6 HPWM signal generation with PIC18F4431

    Hi,
    I'm not using a simulator, I just sent the values to the PC and plotted them with EXCEL. Here's the exact code I used to test with:
    Code:
    DEFINE LOADER_USED 1
    DEFINE OSC 20
    DEFINE HSER_BAUD 19200
     
    i VAR BYTE
    T VAR BYTE
    uDuty VAR WORD
    vDuty VAR WORD
    wDuty VAR WORD
     
    Main:
    For i = 0 to 2   'Make three periods
      T=0
        
       for T=0 to 255
       ' PWM U phase calculation
       uduty=((sin(t)+128)*4)  
          
       ' PWM V phase calculation
       vduty=((sin(t+85)+128)*4)
        
       ' PWM W phase calculation
       wduty=((sin(t+170)+128)*4)
       
       HSEROUT [DEC uDUTY, ",", dec vDUTY, ",", dec wDUTY, 13]
      next
    NEXT
    WereDone:
    Goto WereDone
    Try removing C3, C6 and C8 to start with.

  13. #13

    Default Re: 6 HPWM signal generation with PIC18F4431

    Quote Originally Posted by HenrikOlsson View Post
    Hi,
    I'm not using a simulator, I just sent the values to the PC and plotted them with EXCEL. Here's the exact code I used to test with:
    Code:
    DEFINE LOADER_USED 1
    DEFINE OSC 20
    DEFINE HSER_BAUD 19200
     
    i VAR BYTE
    T VAR BYTE
    uDuty VAR WORD
    vDuty VAR WORD
    wDuty VAR WORD
     
    Main:
    For i = 0 to 2   'Make three periods
      T=0
        
       for T=0 to 255
       ' PWM U phase calculation
       uduty=((sin(t)+128)*4)  
          
       ' PWM V phase calculation
       vduty=((sin(t+85)+128)*4)
        
       ' PWM W phase calculation
       wduty=((sin(t+170)+128)*4)
       
       HSEROUT [DEC uDUTY, ",", dec vDUTY, ",", dec wDUTY, 13]
      next
    NEXT
    WereDone:
    Goto WereDone
    Try removing C3, C6 and C8 to start with.
    In reality, I think that my RC filter in Proteus is bad.

    If I watch the raw PWM outputs, it seems perfectly good (with correct phase angles and duty cycles). However, in extreme duty (like 0 or 1023), the PWM "jumps" (like before, I think it's a sim issue, I will try the PIC in the real life with an oscilloscope).

    In other words, my code is working quite well now, thanks for the "**", I didn't know this operator before, until now.

  14. #14
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    Default Re: 6 HPWM signal generation with PIC18F4431

    Hi,
    Like I said in an earlier post, I think it is the dead-time insertion that makes the waveform "jump" at the extreme ends. Do try it with real hardware and let us know how it goes. Just remember that if you low-pass filter the PWM to watch it on a scope might not see any artifacts introduced by the deadtime insertion - if indeed that is what's causing it. So make sure you watch the "raw" PWM signals as well in order to see if it behaves as in the simulator.

    As a simple test, try removing the deadtime insertion from the code and see if it still looks strange in the simulator.

    /Henrik.

  15. #15

    Default Re: 6 HPWM signal generation with PIC18F4431

    Quote Originally Posted by HenrikOlsson View Post
    Hi,
    Like I said in an earlier post, I think it is the dead-time insertion that makes the waveform "jump" at the extreme ends. Do try it with real hardware and let us know how it goes. Just remember that if you low-pass filter the PWM to watch it on a scope might not see any artifacts introduced by the deadtime insertion - if indeed that is what's causing it. So make sure you watch the "raw" PWM signals as well in order to see if it behaves as in the simulator.

    As a simple test, try removing the deadtime insertion from the code and see if it still looks strange in the simulator.

    /Henrik.
    Yes, of course I've readed your post above. I've modified the code (add +3 to the end of each line), now the PWM signal doesn't "jump" anymore.
    However, if I remove the deadtime or even modify it, the jumpy PWM remains.

    Now signals are better, but sine are not perfect for the highest frequencies, I think that my low-pass filter hasn't good R and C values (1k and 1000nF).


  16. #16
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    senertek Guest

    Default Re: 6 HPWM signal generation with PIC18F4431

    hi ,
    I have already developped many ac inverters range 0.75 kw to 915 kw..with . I seen this thread ..it s very good..to see picbasic projects in this field....
    Designing one 3 phase ac inverter is not easy project...you must know many kind of points about high voltage igbt , drivers , dcbus topologys ,emc ,emi , multi tasking etc...(it take many years)
    If you want , I can help for your project..
    I can try your codes with my high voltage kits , igbt driver modules ...and inform you ..codes works or not...

    savas

  17. #17

    Default Re: 6 HPWM signal generation with PIC18F4431

    Quote Originally Posted by senertek View Post
    hi ,
    I have already developped many ac inverters range 0.75 kw to 915 kw..with . I seen this thread ..it s very good..to see picbasic projects in this field....
    Designing one 3 phase ac inverter is not easy project...you must know many kind of points about high voltage igbt , drivers , dcbus topologys ,emc ,emi , multi tasking etc...(it take many years)
    If you want , I can help for your project..
    I can try your codes with my high voltage kits , igbt driver modules ...and inform you ..codes works or not...

    savas
    Thanks.

    Well, I'm doing studies in electrical engineering, so I've a litte knowledge about this.
    I'm using an intelligent IGBT module from STMicroelectronics, the STGIPS20K60 (datasheet : http://www.st.com/internet/com/TECHN...CD00244265.pdf).

    No drivers needed (they're integrated), just optocouplers.

  18. #18

    Default Re: 6 HPWM signal generation with PIC18F4431

    Ok, a little update.

    I've tested the program on the real PIC with an oscilloscope. All of the output signals are correct, but the sine cycle is very slow (about 4 seconds to make a complete sine period, so f=1/4=0,25Hz).
    The PWM frequency seems correct (3,245kHz).
    I've defined correctly the configuration fuses (or bits), with "HS oscillator" setting, because I'm using a 40MHz quartz oscillator connected to OSC1/OSC2 pins with 22pF ceramic capacitors.

    The code (note I'm not using the FOR... NEXT loop in this case, like the upper programs, it's a lot faster if I use the FOR... NEXT loop, but I don't know why) :

    Code:
    'PIC initialization
    DEFINE OSC 40      
    DEFINE LCD_EREG PORTD
    DEFINE LCD_DREG PORTD
    DEFINE LCD_EBIT 0
    DEFINE LCD_RSBIT 1
    
    
    'DT interrupt system include
    INCLUDE "DT_INTS-18.bas"     ' Base Interrupt System
    INCLUDE "ReEnterPBP-18.bas"  ' Include if using PBP interrupts
    
    
    'Port registers configuration
    PORTB=%0          ' Clear ports
    TRISB=%11000000   ' PWM 0,1,2,3,4,5 outputs
    
                                
    'PCPWM registers configuration
    DTCON=%110        ' Deadtime (600ns)
    PTCON0=%100       ' 1:1 postscale, Fosc/4 1:1 prescale, free running mode
    PTCON1=%10000000  ' PWM time base is ON, counts up, 19.45kHz/4
    PTPERL=%0         ' PWM low-side
    PTPERH=%1         ' PWM high-side
    
    	
    'PWM registers configuration
    PWMCON0=%1000000  'PWM 0,1,2,3,4,5 set in pair mode
    PWMCON1=%1        'PWM timer sync configuration
    
    
    'Interrupt processor
    ASM
    INT_LIST  macro    ; IntSource, Label, Type, ResetFlag
            INT_Handler   TMR1_INT,  _pwmint,   PBP,  yes
        endm
        INT_CREATE     ; Creates the interrupt processor
    ENDASM
    
    
    'Timer configuration
    T1CON=%10000001            ; Prescaler = 1:8, TMR1ON, 16-bit counter
    @ INT_ENABLE  TMR1_INT     ; Enable Timer 1 interrupts
    
    
    'PWM calculation variables
    uduty VAR WORD     'U phase duty
    vduty VAR WORD     'V phase duty
    wduty VAR WORD     'W phase duty
    dutydiv var WORD   'Frequency diviser
    dutymul VAR WORD   'Duty multiplier
    t VAR byte         'Incremental value
    
    
    'Variables definition
    dutydiv=0       'Range : 0-65535
    dutymul=65535   'Range : 0-65535 (for exemple, 32767=0.5)
    t=%0            'T initial value
    
    
    'Main program loop
    mainlp:
    
    HIGH PORTA.0
    pause 100
    LOW PORTA.0
    pause 100
    
    goto mainlp
    
    
    'PWM calculation and update interrupt
    pwmint:
    
        'Frequency diviser
        pauseus dutydiv
    
        'PWM U, V, W phases calculation
        uduty=(((sin(t)+%01111111)*%100)**dutymul)+%100
        vduty=(((sin(t+%01010101)+%01111111)*%100)**dutymul)+%100
        wduty=(((sin(t+%10101010)+%01111111)*%100)**dutymul)+%100
    
        'PWM U phase update
        PDC0L=uduty.LOWbyte
        PDC0H=uduty.HIGHByte
    
        'PWM V phase update
        PDC1L=vduty.LOWbyte
        PDC1H=vduty.HIGHByte
    
        'PWM W phase update
        PDC2L=wduty.LOWbyte
        PDC2H=wduty.HIGHByte
        
        'T variable verification and incrementation
        if t<%11111111 then 
        t=t+%1
        else 
        t=%0 
        endif
    
    @ INT_RETURN
    I think it's a TIMER problem (TMR1 is at 32kHz, isn't it?)

  19. #19
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    Default Re: 6 HPWM signal generation with PIC18F4431

    Hi,
    Yes, it's probably a timer problem. You have TMR1 set up to derive its clock from the main oscillator (Fosc/4) so 10Mhz in your case. (Your code comments says you have a prescaler of 8 but you don't - it's 1:1.

    TMR1 is a 16bit timer and generates an interrupt when it overflows from $FFFF to $0000. In your case this means that the interrupt frequency is 10MHz/65536 = 152.6Hz. In other words, the pwmint interrupt service routine is executed 156 times per second.

    If a complete sinus cycle consists of 256 "steps" you should get a frequency of 152.6/256=0.6Hz but you claim 0.25Hz so I'm not sure what's going on exactly.

    If you want to speed up the frequency you must increase the interrupt frequency. You do this by preloading TMR1 in the interrupt service routine so that it doesn't have to count all the way from 0. If you, for example, preset it to 32768 you'll get twice as many interrupts per second as when letting it free run.

    /Henrik.

  20. #20

    Default Re: 6 HPWM signal generation with PIC18F4431

    Thanks Henrik, now I use TMR1L and TMR1H registers, I got a 40 Hz sine (it's better).

    I've heavly modified the code, I didn't use the SIN function anymore, but a lookup table with 72 values (5 degrees/value).

    Now, for debugging, I want to vary the timer value. For that, I use two buttons, one for increase (PORTC.4), one for decrease (PORTC.5), and then display the value to my LCD.

    The LCD works fine, but not the inputs. If I push the buttons, nothing happens. No increase or decrease. Same thing in the simulator.

    My code :
    Code:
    ' PIC initialization
    DEFINE OSC 40      
    DEFINE LCD_DREG PORTC
    DEFINE LCD_EREG PORTD
    DEFINE LCD_RSREG PORTD
    DEFINE LCD_EBIT 0
    DEFINE LCD_RSBIT 1
    DEFINE LCD_COMMANDUS 10000
    DEFINE LCD_DATAUS 1000 
    
    
    ' BAS includes
    INCLUDE "DT_INTS-18.bas"
    INCLUDE "Sine_table.bas"
    
    
    ' Port registers configuration
    TRISB=%11000000   ' PWM 0,1,2,3,4,5 outputs
    TRISC=%00110000   ' +/- buttons
    
    ' PCPWM registers configuration
    DTCON=%110        ' Deadtime (600ns)
    PTCON0=%0         ' 1:1 postscale, Fosc/4 1:1 prescale, free running mode
    PTCON1=%10000000  ' PWM time base is ON, counts up, 19.45kHz/4
    PWMCON0=%1000000  ' PWM 0,1,2,3,4,5 set in pair mode
    PWMCON1=%1        ' PWM timer sync configuration
    
    
    ' PWM calculation variables
    ustep var byte
    vstep var byte
    wstep var byte
    uduty var word
    vduty var word
    wduty var word
    timer var word
    amplitude var word
    carrier VAR word
    
    
    ' Variables definition
    ustep=72          ' 360 degrees phase angle
    vstep=48          ' 240 degrees phase angle
    wstep=24          ' 120 degrees phase angle
    timer=60950       ' Frequency adjust (60950=80Hz) 
    amplitude=65535   ' Sinewave amplitude adjust (65535=max amplitude)
    carrier=1023      ' Carrier frequency adjust (1023=13kHz)
      
    
    ' PWM carrier frequency register configuration
    PTPERL=carrier.lowbyte  
    PTPERH=carrier.highbyte
    
    
    ' Inverter startup
    pause 2000
    Lcdout $FE,1 
    LCDOUT $FE,2,"Varidrive 1.0"
    LCDOUT $FE,$C0,"DR Electronique"
    pause 2000
      
      
    ' Interrupt processor 
    ASM
    INT_LIST  macro
            INT_Handler   TMR1_INT,   _pwmint,   ASM,  yes
        endm
        INT_CREATE
    ENDASM
     
            
    ' Timer configuration
    T1CON=%1           
    @ INT_ENABLE  TMR1_INT   
    
    
    test var word
    test=1
    
    
    ' Main program loop
    mainlp:
    
    ' Debug display
    LCDOUT $FE,1
    LCDOUT $FE,2,"Timer var :"
    LCDOUT $FE,$C0,#test
    
    if PORTC.4=1 then test=test-1
    if PORTC.5=1 then test=test+1
    pause 100
    
    goto mainlp
    
    
    ' PWM calculation and update interrupt 
    pwmint:
    
    ' Sinewaves frequency
    TMR1L=timer.lowbyte
    TMR1H=timer.highbyte
    
    ' PWM U phase calculation
    uduty=sine[ustep]
    uduty=uduty<<4**amplitude
    
    ' PWM V phase calculation
    vduty=sine[vstep]
    vduty=vduty<<4**amplitude
    
    ' PWM W phase calculation
    wduty=sine[wstep]
    wduty=wduty<<4**amplitude
    
    ' PWM U, V and W update
    PDC0L=uduty.lowbyte
    PDC0H=uduty.highbyte
    PDC1L=vduty.lowbyte
    PDC1H=vduty.highbyte
    PDC2L=wduty.lowbyte
    PDC2H=wduty.highbyte
    
    ' Phase angle calculation
    ustep=ustep-1
    vstep=vstep-1
    wstep=wstep-1
        
    ' Phase angle reinitialization
    if ustep=0 then ustep=72
    if vstep=0 then vstep=72
    if wstep=0 then wstep=72
     
    @ INT_RETURN
    The faulty code is in bold.
    Last edited by pxidr84; - 27th February 2011 at 10:55.

  21. #21

    Default Re: 6 HPWM signal generation with PIC18F4431

    Problem resolved, I will open a new thread.

  22. #22
    Join Date
    Dec 2012
    Posts
    5

    Default Re: 6 HPWM signal generation with PIC18F4431

    hello, i am new to this forum, I am final year electrical engg. student, my project is 'Speed control of Induction motor using PCPWM in PIC18f4431'. Plz guide me how to go about it, i want to write a code for sinusoidal PWM generation using PCPWM in edge aligned mode.

  23. #23
    Join Date
    Dec 2012
    Posts
    5

    Default Re: 6 HPWM signal generation with PIC18F4431

    Which Simulator you people are using for viewing waveforms???? Thanks

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