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ccowley
Joined: 12 Sep 2009
Posts: 19
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| 10 bit hardware PWM on a 12F683 |
 Posted: Thu Sep 17, 2009 4:45 pm |
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I have read everything I can find on the 10 bit PWM, but I still don't seem to be able to get it working properly. Admittedly I am new to programming in C. I have always programmed PICS with Pic Basic Pro and my transition has been somewhat slow. Pic Basic Pro doesn't support 10 bit PWM and I need it for a smooth fade-up/fade-down of an LED, so I thought this would be a simple project.
Any help for this slow C learner would be greatly appreciated!!!
The code I have been messing with is below. At this point I have just been trying to get it to switch between different brightness levels, not even fade, but it is not working.
PCW Compiler V. 4.099
| Code: |
#include <12F683.h>
#device adc=8
#FUSES NOWDT //No Watch Dog Timer
#FUSES HS //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#FUSES NOCPD //No EE protection
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOMCLR //Master Clear pin used for I/O
#FUSES NOPUT //No Power Up Timer
#FUSES BROWNOUT //Reset when brownout detected
#FUSES IESO //Internal External Switch Over mode enabled
#FUSES FCMEN //Fail-safe clock monitor enabled
#use delay(clock=4000000)
void main()
{
setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_CLOCK_DIV_2);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DIV_BY_1,0,1);
setup_ccp1(CCP_PWM);
set_pwm1_duty(0);
setup_comparator(NC_NC);
setup_vref(FALSE);
setup_oscillator(OSC_4MHZ);
// TODO: USER CODE!!
// int16 duty;
// duty=1000;
while (true)
{
set_pwm1_duty(1000L);
delay_ms (1000);
set_pwm1_duty(500L);
delay_ms (1000);
set_pwm1_duty (1L);
delay_ms (1000);
set_pwm1_duty (128L);
delay_ms (1000);
}
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 17, 2009 5:08 pm |
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Here's an example of 10-bit PWM mode. If you turn the trimpot, it
changes the PWM duty cycle.
| Code: | #include <16F877.h>
#device adc=10
#fuses XT,NOWDT,NOPROTECT,BROWNOUT,PUT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
//================================
void main()
{
int16 value;
setup_ccp1(CCP_PWM);
// Set the PWM frequency for 245 Hz (with a 4 MHz crystal)
setup_timer_2(T2_DIV_BY_16, 254, 1);
setup_port_a(AN0);
setup_adc(ADC_CLOCK_DIV_8); // Divisor for 4 MHz crystal
set_adc_channel(0);
delay_us(20);
while(1)
{
value = read_adc(); // 10-bit ADC result
set_pwm1_duty(value);
}
} |
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ccowley
Joined: 12 Sep 2009
Posts: 19
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| Thanks for trying to help! |
| Posted: Thu Sep 17, 2009 8:36 pm |
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I appreciate the effort at helping me out! As I mentioned, I have read everything I could find on it already, so I have already looked at that code. I guess what I am really asking is, "What is wrong with my code, that it doesn't work?" I must be doing something wrong, but I am not sure what it is. I am still in the process of getting a grip on the C language.
Do you see anything wrong my code? I will continue to tinker around and try to solve the problem. I just thought someone might be able to quickly see what my coding problem was so that I wouldn't have to continue spending so much time with the trial and error route.
Thanks again, I do appreciate the effort! |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 17, 2009 8:43 pm |
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Most of the code in your program is unnecessary for PWM.
Look closely at the functions in my program, and compare the parameters
that I use to the ones that you use in the same functions. You will see
the problem. |
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