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,$8 5,$85,$FD,$FD,$79,_ 'D
$01,$01,$FD,$FD,$FD,$01,$01,$79,$FD,$FD,$85,$A5,$E D,$ED,$69,$01,$01,_ 'IG
$FD,$FD,$FD,$01,$05,$05,$05,$FD,$FD,$FD,$05,$05,$0 5,$01,_ 'IT
$F9,$FD,$FD,$25,$25,$FD,$FD,$F9,$01,$01,$FD,$FD,$F D,$81,$81,$81,$81,_ 'AL
$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$01,$0 1,$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,$8 0,$80,$80,_
$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$8 0,$80,$80,_
$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$8 0,$80,$80,_
$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$8 0,$80,$80,_
$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$80,$8 0,$80,$80,_
$80,$80,$80,$80,$80,$80,$80,$80,$FF] ,LcdReg
call PrintDataLcd
next y
Return

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

End 'of program

[Archangel]

:D Hi Fratello,
You REALLY like those Nokia graphic LCD . . . :D
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

[Jerson]

Looks good to me except I would make the first line this
if w1 < calibra-hyst then high mosfet

[fratello]

Because of "structure" of my code (see memo subroutine) , this procedure don't work :( ... I don't have anymore acces to "memory"... I must try a different way, but I have such little space.

[fratello]

A new, working fine too, version...

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


gosub check
Pause 100
Goto Mainand

memo:

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

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

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

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

return
'================================================= ==============================
check:
SELECT CASE MODE
CASE 1
PWM MOSFET, 255, 300
CASE 2
if w1 < (calibra-1) then
pwm mosfet, 155, 200
else
low mosfet
endif
CASE 3
LOW MOSFET
END SELECTStill have BIG thermal inertia of iron soldering (about 7-8 degree)...

[SKOLS1]

where do you buy Nokia 3310 LCD displays?Can you put a link to the store?Thanks
Do you use Solomon SL-10 soldering iron?

[fratello]

Yes, I use Pensol SL10. The display it's from " people sell everything don't need anymore " :) ... about 1 euro.

[mister_e]

FTR, Nokia 3310 or 5110 are basically the same. they use PCD8544 controller. Seems there's no longer a load of 1-2$ deal 'round here... probably because they are so popular ;)

[SKOLS1]

Yes, I use Pensol SL10. The display it's from " people sell everything don't need anymore " :) ... about 1 euro.
Which program you use to make the "DIGITAL" text?Can you make a tutorial or something like that so I can learn something.
I buy 3 Nokia 3310 mobile phones for 2euros.And now I have 8 of those in my lab :D

[HenrikOlsson]

Hi,
A fullblown PID is probably overkill but, for the record, incPID_mc is the multichannel version of the PID-filter. It works fine with a single channel but it takes a lot more codespace than the original incPID routine.

You can find v1.5 of the single channel version in this post (http://www.picbasic.co.uk/forum/showthread.php?t=5874&p=89457#post89457). And with THAT said it still won't fit the 12F675 due to the limited amount of RAM available in that device.

What I'd do is probably something in the line of what Jerson showed but I'd also add a bias or feedforward based on the setpoint (not the error). If you know that in order to maintain a temperature of say 250°C you need a dutycycle of 40% then, once you're within the window of the regulator you enable the P(I) regulator and add the bias/feedforward to the output.

You'll need to work out a suitable bias/feedforward "gain" since it's not going to be perfectly linear. Since the system (probably) heats up faster than it cools down and you can't have "negative drive" you should err on the low side for the bias/feedforward so that IT alone can never drive the temp OVER the setpoint. If it does the regulator can't bring it down since it can never go "below" 0% PWM.

/Henrik.

EDIT: The original version of incPID, which can be found i post 1 in the thread above, compiles to 314 words on the 12F675 and uses 29 bytes of RAM. Depending on how many bytes of RAM your application uses it MIGHT fit but again, it's probably not worth it.

[mister_e]

probably http://en.radzio.dxp.pl/bitmap_converter/

You draw you screen at the right size (84x48 pixels) in Photoshop, MsPaint (whatever floats your boat), save it as monochrome BMP, then import it in the software, generate the table, then import it in your code.

EDIT: also check this out
http://www.picbasic.co.uk/forum/content.php?r=174-Using-Nokia-3310-LCD

[Archangel]

Depending on how many bytes of RAM your application uses it MIGHT fit but again, it's probably not worth it.
Hello Henrik,
Probably not in Sweden or the USA, but in Romania, it might be very well worth it. Import tax is high there, wages not so much . . . Thanks for helping him.
JS

[fratello]

Thanks to all for support !!! Glad to see people helping others...
I will take attention to inc_PID, but ... now my code is 1002 words :(. The best (so far) solution it's to "upgrade" the PIC (maybe 18F...) but, for moment, I will try to keep this "low-cost variant".

[Ioannis]

Try to compact your code. Maybe repeated code can be a subroutine etc.

Also if you use flags, then declare them as BIT and not as BYTE or even worse as WORD.

If you need a BYTE variable, do not declare as WORD.

Ioannis

[fratello]

Whitout "graphics elements" the code it's 659 words. Maybe it's a good start for use PID ?! (+314 words)

' version 2
@ 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


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


pause 500
LcdReg = %00100001 'LCD Extended Commands.
call PrintCtrlLcd
LcdReg = $E6 '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
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

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

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

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

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

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

return
'================================================= ==============================
check:
SELECT CASE MODE
CASE 1
PWM MOSFET, 255, 300
CASE 2
if w1 < (calibra-1) then
pwm mosfet, 155, 200 'era 500
else
low mosfet
endif
CASE 3
LOW MOSFET
END SELECT
return
'================================================= ==============================
Poz:
LcdReg = %10000000 + 67 ' cursor X
call PrintCtrlLcd
LcdReg = %01000011 ' cursor Y
call PrintCtrlLcd
return
'================================================= ==============================

End 'of program

[mister_e]

You can still shave some bytes...

- you don't need 2 spi routines LCD_ByteOut & PrintDataLcd,
- replace the For-To-Next loop with Repeat-Until ones,
- if at all possible, try to skip the div32.
- use internal timer for delays (not sure it will that much though
- pwm with a high/low loop maybe?
- select case for a couple a if-then

couples of ideas like that. sounds like a nice challenge ;)

[mister_e]

Another thing about the graphic part, I've messed with it a lot recently and I saved a load of code space by skipping the whole SELCT-CASE + Lookup thing by using something like


SearchChar:
read (index), char
if char == TheCharYoureLookingFor then
Gosub PrintIt
index=endtable
endif
index=index+6
if (index)<endtable then SearchChar

But you need to modify a little bit the way your DATA lines are done.


DATA @0,"0",$3E,$51,$49,$45,$3E,_ ';// 0
"1",$00,$42,$7F,$40,$00,_ ';// 1
"2",$42,$61,$51,$49,$46,_ ';// 2
"3",$21,$41,$45,$4B,$31,_ ';// 3
"4",$18,$14,$12,$7F,$10,_ ';// 4
"5",$27,$45,$45,$45,$39,_ ';// 5
"6",$3C,$4A,$49,$49,$30,_ ';// 6
"7",$01,$71,$09,$05,$03,_ ';// 7
"8",$36,$49,$49,$49,$36,_ ';// 8
"9",$06,$49,$49,$29,$1E,_ ';// 9
"+",$08,$08,$3E,$08,$08,_ ';// +
"-",$08,$08,$08,$08,$08,_ ';// -
".",$00,$60,$60,$00,$00,_ ';// .
"G",$00,$02,$05,$02,$00,_ ' grad
"C",$3E,$41,$41,$41,$22,_ ' C
"M",$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
so when you want to display your grad character, just need to send G to that routine above. Simple... if it fits the EEPROM ...

[HenrikOlsson]

Hi,
314 words is the size when compiled by itself. Depending on what functions your code uses it might already have one or more of the PBP library routines included meaning the total size will be less than whatever + 314 words.

But like I said, the problem in this case is likely the amount of available RAM. If my count is correct your code uses 23 bytes and the original incPID uses 29 bytes, then, if I'm not mistaken, PBP adds ~24 bytes for its internal use (might change depending on what library routines are used, I don't know for sure). All in all this adds up to more than the 64 bytes of RAM available on the 12F675.

What I meant with not being worth it wasn't that you should throw a "bigger" PIC at the issue. I meant that I don't think the effort of implementing incPID is worth it considering the performance gain you might get compared to the aproaches already discussed. Sure, it it fits it's wort a try, if it doesn't fit I'd try to make do with what's available.

Finally incPID was written in order to be versatile and easy to use. It's probably possible to reduce the size and amount of RAM needed further if adapting it to a specific application - but that's up to anyone using it to do.

/Henrik.

[cncmachineguy]

I'm sure there is something I am missing here but,


Still have BIG thermal inertia of iron soldering (about 7-8 degree)...


Do you think you can do better then this? Or need to? Now if its an excersize in learning and just the fun of doing it, well thats a great reason. But I would think the tip temp will cool that much if you just blow on the tip. but to raise it will take full power for a few seconds to get it back, then it will overshoot. Just my HO. :)

[Archangel]

I'm sure there is something I am missing here but,


Do you think you can do better then this? Or need to? Now if its an exercise in learning and just the fun of doing it, well that's a great reason. But I would think the tip temp will cool that much if you just blow on the tip. but to raise it will take full power for a few seconds to get it back, then it will overshoot. Just my HO. :)
Just so we are all playing on the same field . . . are we talking degrees C or degrees F ? I am guessing Centigrade so that's more like 13 or 14 Fahrenheit.
Check out Robert's article:
http://itech.fgcu.edu/faculty/zalewski/CDA4170/files/PIDcontrol.pdf

[mister_e]

Sure enough, it's not Kelvin... just sayin :D

[Archangel]

Sure enough, it's not Kelvin... just sayin :D
Hey! He (Kelvin) used to work for me . . . :D

[Jerson]

I can hazard a guess that changing this section of code

vt=adval * 500
vt=div32 1023
grup=vt+grup
PAUSE 10to this

vt=adval >> 1
grup=vt+grup
PAUSE 10might save you a bit of code & ram space. But, I've not checked this, so, you'll beware. Again, if you notice,
I've used an approximation of divide by 2(500/1000) for 500/1023 instead of 1/2.046 I do not think it will matter much if you calibrate
the readings.

[fratello]

Wow ! Great support here ! Thanks to all !!!
In first post You can see : the temperature it's in Celsius degrees. The PID control it's a verry good ideea; sure I will use in future projects !
But...I try to do like Mr. Ioannis :

if w1 < (calibra - 5) then pwm mosfet 255, 300
if w1 < (calibra - 3) then pwm mosfet 155, 250
if w1 < (calibra - 1) then pwm mosfet 100, 200
endif
endif
endifI think to reduce the "power" of heating by adjusting the pwm factors... It's OK ?!

[Ioannis]

1. On the above code you do not need the 3 endif.

2. The credit is not for me. Maybe Jerson's?

Ioannis

[fratello]

Something like this : http://www.picbasic.co.uk/forum/showthread.php?t=5874&p=97665#post97665

[Ioannis]

Oh, I see. OK, but take into account what I noted on the post.

It is slow and may oscillate. I am sure it will. Also depending on the resolution, the dead band may be large. Of course the larger it is the less it will oscillate.

Ioannis

[fratello]

I wrote this :

if w1 < (calibra - 3) then pwm mosfet 155, 250
if w1 < (calibra - 1) then pwm mosfet 100, 200
but the heating start ONLY when w1 < (calibra - 3) !
Why don't start when w1 < (calibra - 1) ?!?

[Ioannis]

And what is the value of w1 then?

Ioannis

[fratello]

Example : if calibra (value for memory, set by user) is 140, the heating start at 137.
I wrote the routine for display those two values : w1 (current temperature) and calibra. The led blink ( PWM out) only when w1 < ( (calibra-3) !

if mode = 2 then
call poz
char = 16
call PrintChar
calibra = vt
LcdReg = %10000000 + 25 ' cursor X
call PrintCtrlLcd
LcdReg = %01000011 + 1 ' cursor Y
call PrintCtrlLcd
'~~~~~~~~~~~~~~~~~ now display results
if (vt dig 2) <1 then
char = 16
call Printchar
else
Char = (vt dig 2)
call PrintChar
endif


Char = (vt dig 1)
call PrintChar

Char = (vt dig 0)
call PrintChar

Char = 16
call PrintChar

Char = 13
call PrintChar

Char = 14
call PrintChar

Char = 16
call PrintChar

Char = 15
call PrintChar
endif

[SKOLS1]

Fratello,can you make a code with MAX6675 thermocouple cold junction sensor?I have one,so I want to use it.

[fratello]

Hi! Why don't You write your own code ?!

[Byte_Butcher]

Fratello,can you make a code with MAX6675 thermocouple cold junction sensor?I have one,so I want to use it.


Here, I'm familiar with the MAX6675 so I'll give you a start...

This should read the MAX6675 and display degrees C & degrees F on a LCD display.
(Pin aliases for LCD not shown, only for the MAX6675)




'Alias pins - MAX6675 temp sensor
MXSCLK var PORTD.0 'MAX6675 Clock
MXCS var PORTD.2 'MAX6675 Chip Select
MXSO Var PORTD.3 'MAX6675 Serial Data

'--Variables-----------------------
kTemp var word 'raw data from MAX6675
tempC var word 'temperature in degrees C
tempF var word 'temp C converted to degrees F


'-----------Read and display temperature from MAX6675-----------
main:
LOW MXCS 'chip select low
shiftin MXSO, MXSCLK, 0, [kTemp\16] 'shift in the data
HIGH MXCS 'chip select high
tempC = kTemp >> 5 'side shift to ditch the stuff to the right of the decimal point and just show whole degrees)
tempF = ((tempC * 18)/10) + 32 'convert C to F

lcdout $fe,1,dec tempC," degrees C ",$fe,$c0,dec tempF," degrees F " 'display the data on LCD

pause 500
goto main

end

[fratello]

So it's possible to write code for 16F628A (16F648A), for example...since 12F675 don't have enough ports. And working with large fonts (if using Nokia LCD disply) , memory, pre-setting, etc...