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lxc032
Joined: 12 Jul 2011
Posts: 5
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| PWM signal program |
 Posted: Fri Jul 29, 2011 10:37 am |
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Hi everyone. I'm developing a PWM dimming program using PIC18F4431. There are two LED strings in my circuit. Everything is working except that when the duty cycle of one of the LED strings achieves 100%, the duty cycle of the other string will suddenly drop to 0%. The main body of my code is listed as follows.
| Code: |
while(1)
{
set_adc_channel(0);
delay_us(20);
Vsense_adc_read_1 = read_adc();
delay_us(20);
Vsense_dimm_1 = (int32)(Vsense_adc_read_1*iADCgain_n16);
PWM_Duty1 = (int16)(Vsense_dimm_1);
PWM_Duty2 = (int16)(PWM_Duty1+3000);
PDC0L = make8(PWM_Duty1,0);
PDC0H = make8(PWM_Duty1,1);
PDC1L = make8(-PWM_Duty2,0);
PDC1H = make8(-PWM_Duty2,1);
}
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I have no idea to figure out the problem. Please give me a help. Thank You~! |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Fri Jul 29, 2011 12:22 pm |
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Since it's not a complete program, no one here can compile, run and see why it fails so....
Add code to send the PWM values to either a local LCD or to a PC terminal program. Also send the ADC value as well.
That way you can easily debug when and why 'it goes funny'. |
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lxc032
Joined: 12 Jul 2011
Posts: 5
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| Posted: Fri Jul 29, 2011 2:39 pm |
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My code is listed as follows.
| Code: |
#include <18f4331.h>
#device adc=10
#use delay(clock=4000000)
#fuses HS,NOWDT,NOPROTECT,NOLVP,NOBROWNOUT,NOPUT,MCLR,BORV27,HPOL_HIGH,LPOL_HIGH,T1STANDARD
//================================================================
#byte PWMCON0=0xF6F
#byte PWMCON1=0xF6E
#byte PTCON0=0xF7F
#byte PTCON1=0xF7E
#byte PTPERL=0xF7B
#byte PTPERH=0xF7A
#byte PDC0L=0xF79
#byte PDC0H=0xF78
#byte PDC1L=0xF77
#byte PDC1H=0xF76
#byte PDC2L=0xF75
#byte PDC2H=0xF74
#byte TMR1H=0xFCF
#byte TMR1L=0xFCE
#byte DTCON=0xF6D
#byte PTMRL=0xF7D
#byte PTMRH=0xF7C
#byte OVDCOND=0xF6B
#byte OVDCONS=0xF6A
void main()
{
signed int16 PWM_Duty1=0;
signed int16 PWM_Duty2=0;
signed int16 Vsense_adc_read_1=0;
signed int16 Vsense_dimm_1=0;
signed int32 iADCgain_n16=20;
set_tris_b(0x0C);
//setup_ccp1(CCP_PWM);
PTCON0=0x00;
PTCON1=0x80;
PTPERL=0xFF;
PTPERH=0x0C;
DTCON=0x07;
PWMCON0=0x5D;
PWMCON1=0x00;
setup_adc_ports(sAN0);
setup_adc_ports(sAN1);
setup_adc_ports(sAN2);
setup_adc_ports(sAN3);
setup_adc(ADC_CLOCK_DIV_16);
//setup_timer_2(T2_DIV_BY_16,255,1);
while(1)
{
set_adc_channel(0);
delay_us(20);
Vsense_adc_read_1 = read_adc();
delay_us(20);
Vsense_dimm_1 = (int32)(Vsense_adc_read_1*iADCgain_n16);
PWM_Duty1 = (int16)(Vsense_dimm_1);
PWM_Duty2 = (int16)(PWM_Duty1+3000);
PDC0L = make8(PWM_Duty1,0);
PDC0H = make8(PWM_Duty1,1);
PDC1L = make8(-PWM_Duty2,0);
PDC1H = make8(-PWM_Duty2,1);
}
/*PWM_Duty1 = 3200;
PDC0L = make8(PWM_Duty1,0);
PDC0H = make8(PWM_Duty1,1);
*/
}
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