Strangw results when using PWM command

[Acetronics2]

Hi, Malc

Try this ... and do not forget I/Os and clock defining ...

DEFINE OSCCAL_1K 1

ADCON0 = 0
ANSEL = 0

' Define YOUR I/Os Here !!! TRISIO = % ?????1

led var GPIO.0

i var byte

up:
For i = 1 to 254
Pwm GPIO.0,i,1
next i

for i = 254 to 1 step-1
pwm GPIO.0,i,1
next i

GOTO up

END

Alain

[mister_e]

DEFINE OSCCAL_1K 1

ADCON0 = 0
ANSEL = 0

' Define YOUR I/Os Here !!! TRISIO = % ?????1

The define OSCCAL have nothing usefull to do there
Same for ADCON0 as it's the POR default.. but i agree could be safer

Add CMCON=7 as it's a 12F675 and it have internal comparator multiplexed with GP.0

Main:
for i = 1 to 254
Pwm GPIO.0,i,1
if i=253 then goto down
next i

Bad programming method IMHO, i always prefer to validate the Loop condition before getout and if usefull, set a flag wich say i interrupt the loop... something like

Main:
for i = 1 to 254                                             
    Pwm GPIO.0,i,1
    if i=253 then 
        i=254
        GetOut=1
        endif
   next i

if Getout then DoSomething

In your case, the main problem is most the analog stuff

[malc-c]

Alain, thank for the reply, but that still has the same effect, ie the LED ramps up in brightness, but doesn't ramp down.

Steve,
I never said my coding was tidy

However isn't

Main:
for i = 1 to 254                                             
    Pwm GPIO.0,i,1
    if i=253 then 
        i=254
        GetOut=1
        endif
   next i

if Getout then DoSomething

The same thing as

Main:
for i = 1 to 254                                             
Pwm GPIO.0,i,1
if i=253 then t=1
if t=1 then goto down
next i

in a round about way ? where the condition is replaced with t in my case ?

The thing that is also bugging me if that whilst the loop to increase the brightness works, the one to decrease it doesn't ???

Let me go away and try Steve's suggestion and see if I get any further.

Thanks as always for your inputs

[malc-c]

Steve,

I tried that and it still just ramps up and doesn't seem to want to jump to the down label

@ __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _BODEN_ON

TRISIO.0 = 0   'Set GPIO.0 to output.
ANSEL.0 = 0    'Set GPIO.0 to digital		
GPIO.0 = 0
CMCON = 7 ' PortA Digital inputs
VRCON = 0        ' Voltage reference disabled
OPTION_REG.7 =    0


led var GPIO.0
i var byte
getout var bit

main:
for i = 1 to 254                                             
    Pwm GPIO.0,i,1
    if i=253 then 
        i=254
        GetOut=1
        endif
   next i

if Getout=1 then goto down

down:
for i = 254 to 1 step -1                                            
    Pwm GPIO.0,i,1
    if i=2 then 
        i=1
        GetOut=0
        endif
   next i

if Getout=0 then goto main

[malc-c]

Steve,

I've also tried the following, which seems to flash the LED rather than ramp down in brighness

for i = 254 to 1 step-1                                             
    Pwm GPIO.0,i,1
    if i=2 then 
        i=1
        GetOut=1
        endif
   next i

if Getout=1 then goto down

I can't for the life of me work out what's wrong...

[Acetronics2]

Hi, Malc

I had just forgotten it was for your famous Dr Who's light ...

so, it could not work properly with such a soft ...

There was a thread you've already started about that ... you didn't find anything usable in it ???

http://www.picbasic.co.uk/forum/show...1754#post21754

I'll try to make a search ...

Alain

Seems the HPWM module of the 16F628a you saw was doing the job ... but may be the "slow PWM" thread from Darrel could help here !!! or use a 12F683 ...

[malc-c]

Alain,

Yes this is to do with the "Dr Who" thread in a way. I started a new one as the matters raised in that thread (ie the fact you need to mod the inc files) resolved it.

What I can't understand was that I had used a 12F675 and the for next loops with the pwm command to successfully produce a pulsating LED for my mates project. I sent this off to him but he found that he needed to drive a bulb as the LED didn't give him the brightness he needed. I informed him that he could just used a FET and how to use a zenenr diode etc to produce 5v from a 12v battery, however he has never done any electronics, and may of fried the PIC. I then loaded up the PBP program but for some reason it stops running the down loop of the code.. anyway.. I've sent off the PCB so hopefully he hasn't fried his original PIC and he can simply drop that in and get filming

Thanks guys

[mister_e]

with the existing stuff, try this one

@ __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _BODEN_ON

ANSEL.0  = 0 ' Set GPIO.0 to digital		
CMCON    = 7 ' PortA Digital inputs
VRCON    = 0 ' Voltage reference disabled
TRISIO.0 = 0 ' Set GPIO.0 to output.
GPIO.0   = 0 ' 

LED    var GPIO.0
I      var byte
GetOut var bit

main:
    for i = 1 to 254                                             
        Pwm GPIO.0,i,1
        if i=253 then 
            i=254
            GetOut=1
            endif
       next i

    if Getout=1 then down
    goto main

down:
    getout=0
    for i = 254 to 1 step -1                                            
        Pwm GPIO.0,i,1
        if i=2 then 
            i=1
            GetOut=1
            endif
       next i
    
    if Getout=1 then main
    goto down

and to make something usefull with the GetOut flag, use the following. Tested and work at treat. OK i'd modified the hardware assignement to fit to one of my already build board here

@ __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _BODEN_ON

ANSEL  = 0      ' Set GPIO.0 to digital		
CMCON  = 7      ' PortA Digital inputs
VRCON  = 0      ' Voltage reference disabled
TRISIO = $0F    ' gpio<3:0> : Input
                ' gpio<5:4> : Output

GPIO   = 0      ' clear all outputs

LED    var GPIO.5
PB     var GPIO.0
I      var byte
GetOut var bit

Pause 50        ' oscillator settle time...
OPTION_REG.7 =0 ' enable internal pull-up
WPU = 1         ' enable pull-up on GPIO.0 only

main:
    for i = 1 to 254                                             
        Pwm led,i,1
        if pb=0 then 
            i=254
            GetOut=1
            endif
       next i
    
    if Getout=1 then 
       while pb=0 : wend 
       pause 50
       GETOUT=0
       goto down
       endif
    goto main

down:
    for i = 254 to 1 step -1                                            
        Pwm led,i,1
        if pb=0 then 
            i=1
            GetOut=1
            endif
       next i
    
    if Getout=1 then 
       while pb=0 : wend 
       pause 50    
       GETOUT=0
       GOTO main
       ENDIF
    goto down

HTH