Altering a variable in a loop.

[jmgelba]

Henrik,

Thank you very much for your example. I will give this a try today and post results. Sorry I did not respond earlier. I spent the last few days helping out with a charity walk to raise money for a little girl with type 1 diabetes. Sure was nice to be out in the open air walking by a river instead of being stuck in the dungeon working

[jmgelba]

Ok, so this combines the working crude regulator code with Henriks example code. I havent programmed the pic yet but it does compile.

Define OSC 20
DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 3
DEFINE ADC_SAMPLEUS 50
DEFINE CCP1_REG PORTB
DEFINE CCP1_BIT 3


PORTA = %00000000       ' Turn off all PORTA 
PORTB = %00000000       ' Turn off all PORTB
ADCON0 = %00000001
ADCON1 = %01111000
ADCON2 = %10000111

TRISA = %11100111
TRISB = %11000011


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

Setting VAR BYTE
SettingChanged VAR BIT
DutyCycle VAR BYTE
SETPOINT var byte  'Output current level in 0.1A increments)100 = 1A)

CURRENT VAR WORD
LEDCURRENT VAR WORD
LEDCURRENT1 VAR WORD
high_duty var word
low_duty var word



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

  If Setting = 0 THEN 
  SETPOINT = 0
  endif
  
  If SETTING = 1 then
  Setpoint = 2
  endif
  
  If Setting = 2 then
  SETPOINT = 5
  endif
  
  IF setting = 3 then
  SETPOINT = 9
  endif
  
  IF Setting = 4 then
  SETPOINT = 14
  endif
  
  If Setting = 5 then
  Setpoint = 17
  endif
  
ADCIN 0, CURRENT
LEDCURRENT = CURRENT * 49 /100 *2
LEDCURRENT1 = LEDCURRENT/10

CCP1CON = %00111100
PR2 = 99
high_duty=(dutycycle>>2)        'high 6 bits in CCPR1L
      low_duty=(dutycycle<<6)         'low two bits for CCP1CON
      'low_duty=(low_duty>>2)           'shift back to CCP1CON<5:4>
      low_duty.4=0                     'PWM configuration bit
      low_duty.5=1                     'PWM configuration bit
CCPR1L=high_duty
CCP1CON = $0C
T2CON = 4

IF LEDCURRENT1 < setpoint then
    dutycycle=dutycycle+1
    if dutycycle => 300 then
    dutycycle = 300
ENDIF
ENDIF
IF LEDCURRENT1 > setpoint then
    dutycycle=dutycycle-1
    IF dutycycle > 301 then
    dutycycle = 0
    
ENDIF
ENDIF

Goto Main

[HenrikOlsson]

Hi,
I think that should work. However, since Setpoint doesn change if Setting doesn't change there's no need to assign a value to SetPoint each time thru the loop.
You can move it into the If SettingChanged section, something like:

If SettingChanged THEN
    LOOKUP Setting, [12,23,34,45,56], DutyCycle            ' Assign inital value to DutyCycle variable
    LOOKUP Setting, [0, 2, 5, 9, 14, 17], SetPoint         ' Assign value to setpoint variable    
    SettingChanged = 0                 ' Clear flag
EndIf

Or you could do something like:

IF SettingChanged THEN
  Select Case Setting
    Case 1
       DutyCycle = 12   'Initial dutycycle for setting 1
       SetPoint = 0
   Case 2
       DutyCycle = 23
       SetPoint = 2
   Case 3
       '.......
       '.......
End Select

Try it, see which works best, compiles to the smallest code, is easiest to maintain and understand etc etc.

Good luck!
/Henrik.

[jmgelba]

Good idea! I like your first example because there are less lines to scroll through, and it looks cleaner.

[jmgelba]

Ok I programmed and there are a couple of issues.

There needs to be a time delay between each step up or down that the button is pressed. Right now, pressing either button and it is too fast to set a desired level. This delay cant be put into the loop though as the response of the regulator will be to slow.

Also it doesnt fully turn off and seems to settle at a very low duty cycle when it should be zero.

IF but_0 then
pause 75
eNDIF
if !but_0 then
         if SETPOINT>0 then
            SETPOINT=SETPOINT-1
           endif
           
    endif
    
IF but_1 then
PAUSE 75
ENDIF    
    if !but_1 then
            if SETPOINT<19 then
            SETPOINT=SETPOINT+1
        endif
        
    endif

This button code used before worked well.

[jmgelba]

 If UpButton THEN
    PAUSE 75
    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
    PAUSE 75
    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

Adding the PAUSE 75 fixed the run away issue and gives a quick response to a button press while still being easy to use.

Still havent figured out why at DutyCycle=0 there is still a very low pwm signal that lasts for just a few uS. Or while at setting 5 it rolls over to setting 1.

[HenrikOlsson]

There's a mistake in my code.
The Setting variable can go from 0 to 5 (6 settings) but there's only five entries in the first LOOKUP statement, the one that sets the initial dutycycle.