Altering a variable in a loop.

[martintorres]

not quite understand the idea if you're needing, but I work with a MAP for a car, what I did was to implement a hardware PWM (in the background) and a TMR0 interrupt.
Within the interrupt, which is to read the ADC and modified the pwm ...
With all this, I required no implementing a LOOP and my program was much more efficient

Note: (do not know if the translation is fine >> background = the 2nd plane?)

[martintorres]

would fail to correct the fuses and setup the interruption, but more or less the idea was so (I have to find where I have the complete original program that works well) ... ¨ I understood correctly?

'OPTION_REG =%00111111
PORTA=0:TRISA=%00000001
PORTB=0:TRISB=%00000000
PORTC=0:TRISC=%00000000
PORTD=0:TRISD=%00000000
ADCON1= %10001110 '
T2CON = %00000101
PR2=249
'-----------------------------------------------------------------
@ DEVICE PIC16F877
@ DEVICE PIC16F877, WDT_OFF
@ DEVICE PIC16F877, PWRT_OFF
@ DEVICE PIC16F877, PROTECT_OFF
@ DEVICE PIC16F877, XT_OSC

DEFINE OSC 4
'**** configuracion canal ADC (ADC chanel setting) ***********
DEFINE ADC_BITS 10 
DEFINE ADC_CLOCK 1 
DEFINE ADC_SAMPLEUS 3 
'*********** Configuracion HPWM (HPWM PRESETING) *************
DEFINE CCP1_REG PORTC 
DEFINE CCP1_BIT 2 
DEFINE CCP2_REG PORTC 
DEFINE CCP2_BIT 1 

HAM var word
X VAR WORD
DUTY VAR BYTE
CCP1CON.2=1
CCP1CON.3=1

   On Interrupt Goto int_TIMER0
   INTCON = %10100000


Menu:
DUTY=50
GOSUB salida
GOTO Menu

salida:
PR2=((1024-HAM)*/5625)/100+24
X=(PR2+1)* DUTY /25
CCP1CON.4=X.0
CCP1CON.5=X.1
CCPR1L=x>>2
RETURN

Disable


int_TIMER0:
ADCIN 0,HAM
INTCON = %10100000
Resume 
Enable

regards

[HenrikOlsson]

jmgelba,
The key is to only execute the lookup (or other) code once each time you actually CHANGE the setting - not all the time. If you insist on having it inside a big loop you need a flag to indicate that the setting has changed and that the dutycycle needs to be reset to a new base value.

[jmgelba]

That's exactly it. New current level gets set, pwm is set to a beginning level at the start of the loop. After one loop the pwm is set by the feedback, ignoring the initial start level.

[HenrikOlsson]

Here's the basic principle of using the flag method:

UpButton VAR PortB.0   			' Active high button
DnButton VAR PortB.1   			' Active high button

Setting VAR BYTE
SettingChanged VAR BIT
DutyCycle VAR BYTE

Main:

  If UpButton THEN
    Setting = Setting + 1              ' Increment setting
    If Setting = 6 THEN Setting = 5    ' Make sure it doesn't go beyond 5
    SettingChanged = 1                 ' Set flag indicating new setting
  EndIf


  If DnButton THEN
    Setting = Setting - 1
    If Setting = 255 THEN Setting = 0  ' Make sure it doesn't go below 0
    SettingChanged = 1                 ' Set flag indicating new setting
  EndIf

  If SettingChanged THEN
    LOOKUP Setting, [12,23,34,45,56], DutyCycle
    SettingChanged = 0                 ' Clear flag
  EndIf


  
  ' Your regulator code here...
  ' Your regulator code here...
  ' Your regulator code here...

Goto Main

/Henrik.

[martintorres]

very good your contribution! I find it very helpful to see the logic with other people who program to learn more every day... Thanks Henrik