Dimmer

What would be the solution for following problem. I want to controll 2 opto SCR connected to RB1 RB2. I want one to increase light at the same time as the other Decrease light. The zero detection works perfect and also the delay for the ignition puls for scr1 but what about no 2.How do I solve it with Picbasic pro

Thanks





DELAY_1 = 8500 : us

POS_FLNK:IF ZERODETECT = 0 Then POS_FLNK
NEG_FLNK:IF ZERODETECT = 1 Then NEG_FLNK
DELAY_1 = DELAY_1 - 1

IF DELAY_1 < 7000 Then DELAY_1 = 7000

PauseUs DELAY_1
High out_1
"High out_2"
PauseUs 100
"Low out_1"
Low out_2

GoTo POS_FLNK

Hi,

Since you want to basically complement the 2 outputs, the timing part is easy; assuming you are on 50 Hz, your circuit should see a zero crossing every 10 ms. Therefore, if the delay for one output is X, the other would be (10000-X) us.

Now, the difficult part is that at times X will be less than (10000-X), and more than (10000-X) the other times.

You'll need to therefore determine the sequence of servicing the 2 outputs.

E.g., IF X < (10000-X) THEN PAUSEUS X, SWITCH ON TRIAC1, PAUSEUS (10000-X), SWITCH ON TRIAC2.

IF X > (10000-X) THEN PAUSEUS (10000-X), SWITCH ON TRIAC1, PAUSEUS X, SWITCH ON TRIAC2.

Take care of the situation when X = (10000-X) !

Also allow for the time taken for the actual execution, or else you'll miss the subsequent zero crossing. This you could do by taling the half cycle width to be, say, 9000 us seconds instead of 10000.

Hope this helps!

Regards,

Anand Dhuru

What about the timing of the trigger pulse when they meet in the center "50%dutycyle". At one point the pic will be busy with 100us pulse for SCR1 and at the same time SCR2 should be triggerd. this might give some flicker. maybe the solution would be to make the dimfunction in lets say 10 or 20 steps and then take care of the overlap instead of a linear dimfuntion


Thanks

I've found that the trigger pulse can be as narrow as 5uS; therefore the flicker you refer to is imperceptible.

Also, you could put in a line that caters specifically to this situation; e.g., if X = (1000-X) then High Out1 - Pauseus 5 - Low OUt1 - High Out2 - Pauseus 5 - Low Out2.

BTW, I am using traics, not SCRs. Any particular reason you are using SCRs?

Regards,

Anand

I am using a opto triac Sharp S216S01 so its not a SCR. have to check what the shortest triggpulse can be

Thanks for you input

Hi there,

Which PIC are you using ayway and how are you detecting the zero cross.

It is also important if you are detecting every or alternate zero crosses.

If you are using an interrupt based routine then do the following

1. Play with Timer0 and reset it every zero cross. All turn off the outputs. Its best to do it in assembly.
2. Thus your timer functions as a digital ramp generator now use to loop to detect if the timer has reached the desired value. In this way you do not have to care about the glitches.
3. A 5us time might be not enough. It is best to keep the outputs latched till the next zero cross. This will also let you use low loads under the latching current of the SCR.

Regards

Sougata

I use a 16F84 8Mhz.Zero detection with an opto coupler after rectifyer 100Hz and then a schmittrigger to get the levels right. Have a <1ms puls around zero.
It might be a good idea to make the pulse as long as it can be ,and bring it low just before zero. Sharp "s216s01" recomends 1mS min ,
Assembly might be the best way of solving this ,since my goal is to control 5 outputs , I start with one then work my way up

thanks

I use a resistor as zero detect, 1 meg from phase straight into the port, I then have a 470K resistor on the pin next door to it and swing the bias in an opposite direction to the mains ie:

GPIO.5 is the output pin with the 470K on it - trigger is GPIO.4 which is connected upto the 1M which goes straight to phase. The triac is triggered by a BC327 and i trigger by turning pic from high impedance to low by changing from input to output.

LowSide: 'look for trigger points and trigger triac

IF trigger = 1 Then lowside 'wait for phase to go low
GPIO.5 = 0 'weight input to sense zero crossing
PauseUs dim 'wait for dim period
Output triac 'fire triac
triac = 0
PauseUs 400
Input triac


HighSide:

IF trigger = 0 Then HighSide
GPIO.5 = 1
PauseUs dim
Output triac
triac = 0
PauseUs 400
Input triac

GoTo start

Hi there,

Having the opto-triac driven till the zero cross would take care of inductive loads also.
Provide me with the following :

1. How the outputs would be controlled? (Internal timer /push button etc)
2. Your line frequency

I would try to play with the interrupt part simulate it.

Regards

Sougata

What i wanted to do is a controller for some decorative lights. I want to make a pattern where light fade in / out.
Powersupply = 50 hz 220V

My first plan was to fade in/out between 2 limits on 1 channel "this works ok".
then i wanted to try 2 channels to push the limit "a bit"
Now I can see this extend to like 5 output creating a wave like motion.
may be it will end up with a lot of assembly code and also lower the demands
on "linear control" and go over to fixed steps and a data table


could even parallell 5 pics to achive my goal this would be the last solution

Thanks

Hi,

Understood. The only problem is that I don't have 16F84 ready. However it should work. Do you have a PIC18F452 ready? This is where I am most comfortable. I also have 16F676, 16F73, 16F619 handy. BTW you don't need five PICs.

Regards

Sougata

I have not done this but may be my idea could help.

Using Interrupts, when there is pulse from zero-crossing detector, you could succeed in your house keeping, timing that is.

Entering the ISR, the relevant registers would increment or decrement according the flags you have set in your main program. So there is accurate timing to fire every SCR even 5 or more since the ISR would be triggered every 10ms.

Ioannis

Hi Everybody,

It is possible to trigger n numbers of SCRs within the 10ms(50Hz) time frame. My DMX Dimmer handles 48 of them. There I use a bubble sort algo and actually different interrupt sources. One for syncing the timer with ac, one for firing, listening to USART, fader read and so on. All this handled by two PICs 18F452 @ 40MHZ. The second one is mainly for the download and running of pattern or randomizing them.

I am working on a simplified version using a PIC16F84A (Yes I found one) and trying to acheive a 100% PBP code using the On-Interrupt function. I have no idea about the latency till I get my code running tomorrow and checking on scope. Even the asm interrupt would be quite easy.

You see with a clock frequency of 8MHz--> 2MHz(Fosc/4) / 128 (prescale) / 100 (reset every 10miliseconds), the timer0 would count 156 (50Hz) or 130(60Hz max). Compare this constantly in a loop with preset or increasing / decreasing values and fire the appropriate port.On interrupt

1. Clear all outputs
2. Reset Timer0
3. Return

Thats it. It will be done before the new cycle begins!!!!!!!!!2MIPS

I am working on a two channel version and let you all guys out there juice it up.

BTW most of the PICs have an inbuilt Schmidt Trigger on input ports so the interfacing is pretty easy. I use a couple of resistors a diode bridge and an optocoupler to derive the zero cross sync. It is accurate without any phase latency (as in the case of transformer based).Direct AC feed through high value resistor is also possible and practical but the circuit becomes live and is not recommended for experimenters.(I use it in my remote controlled fan/light dimmer to keep costs under control. It retails for about 18USD!!!!)

The toughest part is possibly randomizing the paterns or using pschychedelic effect with beat detection within the scope of the chosen processor (clock code space, instruction set).

We are having Diwali (the festival of lights) and a holiday to work with a fun project. The entire town is having myriads of lighting displays so why not doing one for the forum. Happy Diwaly to guys out there.

It is midnight now and I can get my hands on the PIC only tomorrow when I get the lunch break. So till then....

Bye!!

Regards

Sougata

Hello everybody
What happend here , did the the project stall

RGDS
BG

Sorry guys,

I could not keep up to my commitments. I lost a very near and dear friend. Give me a couple of days, I will get back with something working.

Regards

A previous thread ==> http://www.picbasic.co.uk/forum/showthread.php?t=1026

Schematic + code (Dimmer.zip) ==> http://www.melabs.com/resources/samples.htm#submitted

Maybe not exactly what you need but should be enough to start

Sorry guys although I did a testing for a single channel version, I couldn't test the five channel one. I am posting the circuit and the code. I request the PIC gurus to have a look at the code and point the flaws. Please do read the notes.doc file for important information.

Regards

Sougata

Thank´s for the code Sougata. I will test it later. However I wrote some code myself and it works.I did not use Interupt´s.. There are some similaritys to what you wrote.

But As i say I will try out your code later

thanks
BG

Can someone help me?
I build the circuit from (Dimmer.zip) ==> http://www.melabs.com/resources/samples.htm#submitted,
and I have this problem:
If I press the increase button (<500ms) ,the lamp go on,full and if I press the decrease button, the lamp go off (normal).
If I try to decrease the intensity from full on, or increase the intensity from off state, the lamp it fllash fast without decreasing/increasing brightness, until the lamp go on or off.
On GP4 I have 50hz, and value at the pin GP2 while press the buttons, increment/decrement pulses by 500 uSec,until the maximum/minimum value, everything look ok.

Any Help?

Thanks!

Have you adapted the program for the 50Hz line freq?

Ioannis

If you mean the maxdelay value, yes.

But if you conect osciloscope and take a look at the pulses from the pic output and the 50Hz at the same time, you will see that the maxdelay value is only for the maximum brightness.

Looks like a bad signal level to me...

What is the voltage of your transformer?
What are your R3 and R4 value?

Try decrease R3 and post your results.

This is the osciloscope measures from the GP4 (AcLine input), and from GP2 (Output to TRIAC).
I use tranformer 8Vac, R3=4k7 and R4=10k.

Look the pictures from 0 to 4. Is from value off to on through 3 steps.


But the lamp still flashing...

Reven,
I've not used that circuit or code you are reffering to but by just looking at your waveforms it seems that the triac is triggered at the same phase angle in case 1, 2, 3 & 4.

The triac only needs a short pulse on the gate and will then hold itself 'on' untill the AC-line crosses zero, at which point it will turn 'off'. That short pulse should be delayed a certain amount of time from the zero crossing.

On your scope pics the triac seems to be triggered exactly 1div from the zero crossing in all cases except full on and full off.

/Henrik Olsson.

Hi, reven

Henrik is right ...

Here, the pulse length is not the thing to be variable.

but you must vary the time between zero voltage detection and triac gate firing ...

Long time = weak light
short time = full light

remember once the triac is turned on it stays turned ON until current becomes null.


Alain

Here, you had programmed a ... DC Dimmer !!!

I think you have right...
As Henrik says ,now the triac is triggered at the same phase angle in all cases.
I must change my code to put the pulse position in a variable.
Thanks all of you!
I will inform you about my progress!




BTW, take a look at the code,bacause I checked it many times and I could not find where the problem is.

http://www.picbasic.co.uk/forum/atta...0&d=1103787743

Thanks again,
Reven

Hi, Reven

Just understand what the interrupt routine does instead of should have done ...

""
' ACDetect
' --------
'
' Interrupt routine called by ACLine (GP4) pin state change
'
disable
ACDetect:
if ACline==1 then ' Check for rising edge of AC signal
if triacdelay > 0 then
Triac=1 ' Activate TRIAC

Alain's : ;;; No,No,No ... here we have to wait for ( Maxdelay - Triacdelay ) !!! THEN fire the Triac for, say, 20µs ... then let things quiet.

if FullBright==0 then ' In case Brightness flag is not set
pauseus triacdelay ' do the selected delay
triac=0 ' Disable TRIAC
endif
else
triac=0
endif
endif
INTCON.0=0 ' Clear GPIF (interrupt on GP4 change)
resume
enable

""


*** This part of program smells to have been taken from a heather using burst mode dimming ...

Sorry, Steve ... je t'aimais bien ( avec la musique de circonstance ... )

Alain

mmm, sorry all. something should be wrong in what i posted. I used that program in various app and it worked... let me the time to return at home(Next week) and i'll compare the posted version and what i use...

Many thousands of appologies.

Can't wait to return home... use the following ACDetect routine instead.
this should work.

Code:

---

disable
ACDetect:
if ACline==1 then
    '
    '    Rising edge of AC signal
    '    ========================
        if triacdelay then              ' A delay is set by user
                                        ' 
            if FullBright==0 then      ' Full Brightness flag is not set
            pauseus maxdelay-triacdelay '    do the selected delay
            triac=1                    '    enable TRIAC                   
            else                        '
                    triac=1                ' Full Brightness flag is set
                                        '    enable triac
            endif                      '
                                        '
        else                            '
                triac=0                    ' No Delay set by user... disable Triac
        endif                          '
   
    else                               
    '
    '    Falling edge of AC signal
    '    =========================
        if fullbright==0 then triac=0  ' Disable the Triac on falling edge of
                                        ' Ac signal
    endif
INTCON.0=0 ' Clear GPIF (interrupt on GP4 change)
resume
enable

---

Yeah i know you can also use Pulsout and forget the Falling edge detection... as you wish. Both will work.

First, I write something like this:

' Interrupt routine called by ACLine (GP4) pin state change
disable
ACDetect:

if ACline=1 then ' Check for rising edge of AC signal

pauseus triacdelay ' do the selected delay
Triac=1 ' Activate TRIAC
pauseus 20
Triac=0 ' Disable TRIAC

endif


INTCON.0=0 ' Clear GPIF (interrupt on GP4 change)
resume
enable



and because I use half wave signal from the AC line on GP4, finaly something like this:


' Interrupt routine called by ACLine (GP4) pin state change
disable
ACDetect:

if ACline=1 then ' Check for rising edge of AC signal

pauseus triacdelay ' do the selected delay
Triac=1 ' Activate TRIAC
pauseus 20
Triac=0 ' Disable TRIAC


'send a second pulse to triac,after 10ms, like the full wave
pause 10
Triac=1 ' Activate TRIAC
pauseus 20
Triac=0 ' Disable TRIAC


endif


INTCON.0=0 ' Clear GPIF (interrupt on GP4 change)
resume
enable





Again, thanks all of you!
Reven

Hello - I am trying to compile the dimmer program and I am getting an error at the CONFIG fuse:

@ __CONFIG _INTRC_OSC_CLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF

It's giving me:

Error ACLAMP~1.ASM 60: [235] opcode expected instead of '__config'

Can anyone tell me what I am doing wrong?

PBP 2.43 - PIC12F675

Atom058

Quote:

---

Can anyone tell me what I am doing wrong?

---

You're using PM instead of MPASM to compile your code

if you want to use PM, you must use the @ DEVICE directive instead.

See the Faq about that. There's a whole thread about how to set config fuses in your code.
http://www.picbasic.co.uk/forum/showthread.php?t=543

You're the MAN! Totally missed that one. Thanks!

Hello - I am trying to build the Dimmer Circuit as described and was wondering if someone could critique the attached circuit diagram. I have built this and do not seem to be able to get it to work and if it is not my design then it must be my code (both of which I obtained here). Any comments will be appreciated. I am using part numbers, schematic and code that are described here: http://www.melabs.com/resources/samples.htm#submitted
Thanks! Atom058

Here's the schematic....

%%^%^&*&!#@$! it's my silly mistake. I will have to update the whole thing soon. Use...
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1116&stc=1&d=116053407 7">

You only have to move 1 wire...

PCB mod... really easy
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1117&stc=1&d=116053452 8">
SORRY SORRY SORRY SORRY SORRY SORRY SORRY SORRY SORRY SORRY

Mister-E - No harm done! Thanks for the quick response! I will give it a try tonight and we'll see what happens.

Atom058

I was trying to program a PIC12F675 to work with this dimmer design and I am obviously missing something. I copied the code from the Dimmer example and it was not working so I moved to a breadboard to do some testing. I can not even make an output on these PIC's go high! I know I am missing something but I can't imagine what it is! Here is the code - as simple as it is:

@ DEVICE INTRC_OSC_NOCLKOUT & WDT_ON & MCLR_OFF & PWRT_ON & BOD_ON

PAUSE 500
CMCON=7 ' Disable analog comparator
ANSEL=0 ' Disable analog converter

TRISIO = %11111111
TRISIO.0 = 0
TRISIO.1 = 0
TRISIO.2 = 0
TRISIO.3 = 0
TRISIO.4 = 0

HIGH GPIO.0
HIGH GPIO.1
HIGH GPIO.2
HIGH GPIO.3
HIGH GPIO.4

Start:
GOTO Start

END

Now, correct me if I am wrong, but I should be able to measure 5V at each of the 5 outputs above. I get nothing. I have tried several PICs and get the same results. I've written hundreds of programs for different PICs and this one has beaten me. I know the solution is unbelieveabley simple, but GEEZ!

Quote:

---

Originally Posted by Atom058

...
@ DEVICE INTRC_OSC_NOCLKOUT & WDT_ON & MCLR_OFF & PWRT_ON & BOD_ON...

---

Hi Atom,

First thing, try these instead of the line above.

Code:

---

@ DEVICE pic12F675, INTRC_OSC_NOCLKOUT
@ DEVICE pic12F675, WDT_ON
@ DEVICE pic12F675, PWRT_ON
@ DEVICE pic12F675, MCLR_OFF
@ DEVICE pic12F675, BOD_ON
@ DEVICE pic12F675, CPD_OFF
@ DEVICE pic12F675, PROTECT_OFF

---

These should fix your problem.


Second thing, GP3 is an input-only pin. Never goes high.



----------------------

Your @ device line is faulty...
If you'e using PM to compile your code you must use something like

Code:

---

@ device  pic12F675, intrc_osc_noclkout, wdt_on, mclr_off, protect_off

---

With MPASM

Code:

---

@ __config _INTRC_OSC_NOCLKOUT & _WDT_ON & _MCLRE_OFF & _CP_OFF

---

OUPS! SAYZER WHY YOU REPLYED AT THE SAME TIME :D

i know this one is familiar to you :D:D