phse control light dimmer

[bonhome]

hello i h've been working on a phase control light dimmer project with pic 16f877 microcontroller with ccs pic c compiler driving a MOC3021 optotriac
controling a lamp 220 v 50 hz .i can say that i know the principle well ,so i wrote this c code,and for some reason it does not work.
well in this case i am trying to control the lamp at 3 defrents phases 100,75,50 %
int porcentage=100;
#int_EXT
EXT_isr()
{
if(porcentage==50)
{
delay_us(4990);
output_high(PIN_C0);
delay_us(100);
output_low(PIN_C0);
// set_timer1(5000);

}
else if(porcentage==75)
{
delay_us(2480);
output_high(PIN_C0);
delay_us(100);
output_low(PIN_C0);
// set_timer1(2500);
}
else if(porcentage==100)
{
output_high(PIN_C0);
delay_us(100);
output_low(PIN_C0);

}


}



void main()
{

port_b_pullups(FALSE);
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_2(T2_DISABLED,0,1);
enable_interrupts(INT_EXT);
ext_int_edge( H_TO_L );
enable_interrupts(GLOBAL);
set_tris_c(0b11111110);

while(1){

}

}
so if anyone could help me i would apretiate it. thank you.

 

[dfullmer]

I assume you are working from a zero cros point and controlling a triac! Is this correct? When you say it doesn't work what do you mean exactly/ What happens?

dfullmer

 

[nandhu015]

Your logic seems to be correct.

Post your full schematic, there may be some error in zero crossing.

 

[microlab]

hi

when you control the phase, you have to detect the zero crossing at both the sides and apply the triggering sequence

ml

 

[bonhome]

the zero cross crcuit is working fine,it does trigger an externel interrupt ,wich execute an ISR.i am using isis proteus simulator an for some reason i have a timing probleme and it is crashing .

 

[nandhu015]

the zero cross crcuit is working fine,it does trigger an externel interrupt ,wich execute an ISR.i am using isis proteus simulator an for some reason i have a timing probleme and it is crashing .

simulator crashes??
may be software problem.

Tell me what is happening clearly..

 

[prmurthy]

Hi everybody

If we need to control at different phases we need to use non-zero cross TRIAC Driver example MOC3011. Now detect the zero cross using voltage drop and opto-couple accross the Live or Hot wire. Remember here not to connect reverse. That's all rest is done by software, we can control a very smooth almost linear control.

Thankyou

PS: Try to change to MOC3011 and see. I think you are trying to sense through half wave rectifier. I suggest direct sense would give you better results. Connect a IN4007 and then 33K on the live or Hot wire and connect to an Opto-coupler like 4N35, now sense the output of optocoupler.

 

[bonhome]

in the 50 % case i need to wait 5ms to trigger the TRIAC ,with the osciloscope it shows that is longer then the entire sicle of the input .allthough i ma using i 50hz input ,onse a zeros cross interrupt the microcontroller a 5ms delay seems to hang the ISR longer than the time it takes for the next interruption.

---------- Post added at 14:47 ---------- Previous post was at 14:45 ----------

using a 50hz frequency should have 20ms sicle and 2 times interruption after each 10ms ,the problem that my code is for some reason concedering a 5ms delay longer than the 10ms of half sicle.

---------- Post added at 14:52 ---------- Previous post was at 14:47 ----------

thanks for your post prmurthy ,but the zeros cros sence is working fine,and i am using a non eros cross TRIAC driver MOC3021

 

[cbyrn071]

I am trying to design a very simular circuit, only using circuitry and no pic.. Since I am having problems I am considering using the sam pic. I tryed to stay away from programming, I find its not my strong point!!:-|
Does the trigger have to be an interrupt?? Im looking to vary the phase output buy varying a voltage input to the pic from 0-5 volts. Its an analog signal so would i have to use an A/D converter. Is this possible??
Thanks

 

[hugo]

Hi,

Take a look at this light dimmer (mikroc) project :

 

[Praful]

Dear bonhome,
Did u get the succes in phase control AC dimmer.. Please send reply I'm also stuck here.
Thanking You.
Praful