Soldering station

[fratello]

Using Pensol SL10, one cheap 12F675 and N3310 display, I made for myself this soldering station. Works fine, the mos-fet remains cool, but... I wonder if my code it's the better way to drive the mos-fet and keep most accurate temperature of iron ("pwm mosfet, 255, 300").
Any advice it's wellcome ! Thanks in advance !

'===============================================================================
'*                   Statie digitala de lipit, cu display de NOKIA 3310        *
'*                 Digital solering station with N3310 display            *    
'*                           by Dan Niculescu, june 2011                        *
'===============================================================================

@ DEVICE PIC12F675, intrc_osc_noclkout, wdt_off, mclr_off
DEFINE OSC  4
DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 3
DEFINE ADC_SAMPLEUS 50

CMCON    = 7
TRISIO   = %001001
INTCON   = 0 
GPIO     = 0

ANSEL    = %00010001
ADCON0   = %10000001
wpu      = %00000010
 
            D_C      var     GPIO.2       
            SDIN     var     GPIO.4
            SCK      var     GPIO.5
            MOSFET   var     GPIO.1
          buton    var     GPIO.3

            LcdReg          var  byte        
            x               var  byte
            y               var  byte
            z               var  byte
            a               var  byte
            PosX            var  byte
            PosY            var  byte
            Chr             var  byte
            LcdData         var  byte
            Offset          var  byte
            Char            var  byte
            adval           var  word
            w1              var  word
          vt              var  word
          cnt             var  byte
            grup            var  word
            mode               var  byte
          calibra         var  word
            i               var  byte
             
            DATA @0,$3E,$51,$49,$45,$3E,_       ' 0                   
                    $00,$42,$7F,$40,$00,_       ' 1
                    $42,$61,$51,$49,$46,_       ' 2
                    $21,$41,$45,$4B,$31,_       ' 3
                    $18,$14,$12,$7F,$10,_       ' 4
                    $27,$45,$45,$45,$39,_       ' 5
                    $3C,$4A,$49,$49,$30,_       ' 6
                    $01,$71,$09,$05,$03,_       ' 7
                    $36,$49,$49,$49,$36,_       ' 8
                    $06,$49,$49,$29,$1E,_       ' 9
                    $08,$08,$3E,$08,$08,_       ' +
                    $08,$08,$08,$08,$08,_       ' -
                    $00,$60,$60,$00,$00,_       ' .
                    $00,$02,$05,$02,$00,_       ' grad
                    $3E,$41,$41,$41,$22,_       ' C
                    $7F,$02,$0C,$02,$7F,_       ' M     
                    $00,$00,$00,$00,$00,_       ' space
                 $08,$04,$7F,$04,$08,_       ' arrow up
                    $20,$40,$7F,$40,$20         ' arrow down

    Low D_C                                  'Command/Data

           pause 500                 
           LcdReg  =  %00100001         'LCD Extended Commands.
           call    PrintCtrlLcd
           LcdReg  =  $FF               'Set LCD Vop (Contrast).Initial $C5
           call    PrintCtrlLcd
           LcdReg  =  %00000110         'Set Temp coefficent.
           call    PrintCtrlLcd
           LcdReg  =  %00010011         'LCD bias mode 1:48.
           call    PrintCtrlLcd
           LcdReg  =  %00100000         'LCD Standard Commands
           call    PrintCtrlLcd
           LcdReg  =  $0C               'LCD in normal mode.  $0D inverse
           call    PrintCtrlLcd                 
Pause 100
Call CursorHome
Pause 100               
Gosub LCD_Clear
mode = 0
Pause 500                ' time to give-up :) 
'===================== READING VOLTAGE ==============================
Main:
low mosfet
call Borderline
pause 50
 vt=0
 grup=0
     for cnt = 1 to 20
 ADCON0.1 = 1
 WHILE ADCON0.1 = 1 : WEND
 Pause 10
 adval.HighByte = ADRESH
 adval.LowByte = ADRESL
 PAUSE 10
     vt=adval * 500
     vt=div32 1023
     grup=vt+grup
 PAUSE 10
     next cnt
 w1=grup / 20

'===================== setting cursor for display the voltage
                LcdReg  =  %10000000 + 25        ' cursor  X
                call    PrintCtrlLcd
                LcdReg  =  %01000011             ' cursor  Y
                call    PrintCtrlLcd
'===================== now display results 
 if (w1 dig 2) <1 then
                char = 16  
                call Printchar
                else         
                Char = (w1 dig 2)            
                call    PrintChar 
 endif      


                Char = (w1 dig 1)           
                call    PrintChar

 if (w1 dig 0) < 5 then            
                Char = 0          
                call    PrintChar  
        else
                char = 5
                call PrintChar
 endif                         
                Char = 16                 
                call    PrintChar
            
                Char = 13
                call  PrintChar
               
                Char = 14
                call  PrintChar

                
if buton = 0 then 
mode = mode + 1
gosub memo
endif


gosub check
Pause 100                
Goto Main

'================== L C D ===========================================                

CursorHome:     LcdReg  =  %10000000            ' cursor Home
                call    PrintCtrlLcd
                LcdReg  =  %01000000            ' cursor Home
                call    PrintCtrlLcd
                return

PrintChar:      offset = Char * 5          
            
                for a = 1 to 5                
                    read offset, LcdReg
                    call  PrintDataLcd
                    offset = offset + 1
                next a
                LcdReg = 0
                call    PrintDataLcd
                return
                                    
PrintCtrlLcd:   D_C = 0                             

PrintDataLcd:   for x = 1 to 8                
                    SDIN = LcdReg.7              
                    SCK = 1
                    LcdReg = LcdReg << 1
                    SCK = 0
                next x               
                D_C = 1
                return               
                
LCD_Clear:
                PosX=0:PosY=0:Gosub LCD_GotoXY
                D_C = 1
                FOR Chr=1 TO 252
                    LcdData=0:Gosub LCD_ByteOut
                    LcdData=0:Gosub LCD_ByteOut
                next Chr
                return

LCD_GotoXY:
                D_C = 0
                LcdData=%01000000 | PosY :Gosub LCD_ByteOut
                LcdData=%10000000 | PosX :Gosub LCD_ByteOut
                return

LCD_ByteOut:
                SHIFTOUT SDIN,SCK,1,[LcdData]
                return  

GotoXY:                
LcdReg = %01000000 | Posy : call    PrintCtrlLcd    'Y
LcdReg = %10000000 | Posx : call    PrintCtrlLcd    'X

'===============================================================================
memo:

if mode = 1 then
 gosub poz
 char = 17
 call    PrintChar
 calibra = 4800
endif

if mode = 2 then  
 gosub poz
 char = 15
 call    PrintChar
 calibra = vt
endif

if mode = 3 then 
 gosub poz
 char = 18
 call printchar
 calibra = 10
endif

if mode > 3 then 
  mode = 0
 gosub poz
 char = 16
 call printchar
endif

return
'===============================================================================
check:
if mode >= 1 then
    if w1 < (calibra-2) then  pwm mosfet, 255, 300       
    else
    low mosfet
endif
return
'===============================================================================
Poz:
                LcdReg  =  %10000000 + 67        ' cursor  X
                call    PrintCtrlLcd
                LcdReg  =  %01000011             ' cursor  Y
                call    PrintCtrlLcd
return
'===============================================================================               
BorderLine:                          
'=================================== RAW UP
      LcdReg  =  %10000000            ' cursor  X  
      call    PrintCtrlLcd
      LcdReg  =  %01000000            ' cursor  Y
      call    PrintCtrlLcd
      for y = 0 to 83                   
      LOokup y, [$FF,$01,$01,$01,$01,_
                 $01,$01,$01,$01,$01,$01,$01,$01,$01,$FD,$FD,$FD,$85,$85,$FD,$FD,$79,_        'D
                 $01,$01,$FD,$FD,$FD,$01,$01,$79,$FD,$FD,$85,$A5,$ED,$ED,$69,$01,$01,_        'IG
                 $FD,$FD,$FD,$01,$05,$05,$05,$FD,$FD,$FD,$05,$05,$05,$01,_                    'IT
                 $F9,$FD,$FD,$25,$25,$FD,$FD,$F9,$01,$01,$FD,$FD,$FD,$81,$81,$81,$81,_        'AL
                 $01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$FF] ,LcdReg       
      call    PrintDataLcd
      next y
'===================================  RAW 1 to 4                               
for i= 1 to 4
posx=0
posy=i
gosub GotoXY
               lcdReg= $FF
               call    PrintDataLcd
next i

for i = 1 to 4
posx=83
posy=i
gosub GotoXY
               lcdReg= $FF
               call    PrintDataLcd
next i   
'===================================  RAW DOWN              
      LcdReg  =  %10000000           
      call    PrintCtrlLcd
      LcdReg  =  %01000101            
      call    PrintCtrlLcd
      for y = 0 to 83                   
      LOokup y, [$FF,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,_             
               $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,_          
               $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,_          
               $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,_          
               $80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,_          
               $80,$80,$80,$80,$80,$80,$80,$80,$FF] ,LcdReg
      call    PrintDataLcd
      next y 
Return

'===============================================================================

End             'of program

[Archangel]

Hi Fratello,
You REALLY like those Nokia graphic LCD . . .
I think they're pretty cool too, Now as for USEFUL comments . . . According to the engineer from France who writes the Dark Side column in Circuit Cellar, . . Robert La Coste ? his suggestion is to use a PID loop to give you some Hysteresis to your temperature to prevent overshoot and undershoot of tip temp. Search the forum there is a pretty good one or more in circulation.

[fratello]

Thanks for advice !
I found this : incPID_mc.pbp Author : Henrik Olsson. GREAT WORK !
Unfortunately the code don't fit in my small 12F675 ; it's a solution to upgrade to a bigger PIC (18F2550 ?) but... for my small device it's another way ?!
...and yes, I like this display : it's verry cheap (about 1 euro) and easy to use. One 2x16 LCD display it's 6 euro and don't look so nice .

[Jerson]

I can assume you're almost at the limits of the code space with your current code. The best option, I reckon, to get reasonably good control with your existing setup would be to try PI control. As it is, you are using the PWM function. Just compute the proportional output to get a smoother control.
Modify your check routine so that the PWM function outputs 255 when far lower than the setpoint, 0 when at it. Now, to compensate the offset of the temperature, you add the integral correction over time. This can be achieved quite easily with integer math alone.

A typical P controller pseudo code
Band con 10 ' this decides the band around SetPoint in which you want proportional control

if Temp < SetPoint-Band then
PWMout = 255 ' full heat
else
if Temp > Setpoint+Band then
PWMout = 0 ' full off
else
' within band, do Proportional heating
Error = SetPoint+Band-Temp ' you want to get the bigger numbers for temp < sv
PWMout = (Error*255)/(2*Band) ' get an output from 255 to 0 over the band from SV-Band to SV+Band, 50% at SV
endif
endif

Adding integral is relatively easy too. You just need a variable to adjust the error over time. Or use a button to snapshot the error and add it as an offset.

IntErr var byte

IntErr = IntErr+(Error/IntTime) ' integrate the error over time

PWMout = PWMout + IntErr
if PWMout > 255 then PWMout = 255 ' limit to usable PWM range

PWM Mosfet, PWMout, 300 ' transfer to the mosfet

Just some ideas.

[fratello]

Thank You so much ! I try and I post the results.

[fratello]

I cannot run my simulation ( AMD Athlon64 X2 DualCore 4200+, 2 GB RAM ?!) ...
It's this code OK ? Thanks !

hyst            CON  2
check:
if mode >= 1 then
    if w1 < calibra-hyst     then pwm mosfet, 255, 300
    if w1 > calibra+hyst     then low mosfet
    if w1 = calibra+hyst-w1 then pwm mosfet,(w1*255)/(2*hyst), 300
endif
return