6 HPWM signal generation with PIC18F4431

[pxidr84]

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 :

' 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.

[pxidr84]

Problem resolved, I will open a new thread.

[oswalam]

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.