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AsmallGuy
Guest
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| 16F684 issue: performance decay with PWM |
 Posted: Wed Mar 18, 2009 3:36 pm |
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Hi, I have something happening inside my 16F684, below is the code of my simple program:
_ it listen on PINs A0 A1 A2 for some button to be pressed via interrupt
_ then it increase/decrease/zero the value of PWM
_ and increments a variable (which represent how many times buttons where pressed)
The behavior is that if I:
_ comment the instructions inside the ending while(true) the system is responsive to button press (empty loop)
_ uncomment (enable) the code inside the while_loop the system becames unresponsive, slow to react and sometimes i miss button press.
I used fast_IO on port C and A; Some of you may guess, the 4 bits output is feeded to a BCD decoder attached to a 7 segment display (to keep track of button press, not yet tested).
What i'm missing?
Tnx.
P.S. PWM-PWM-PWM looking inside the forum there are too many question arising from it  - at first, did i setted right the PWM? (8MHz clock, 20Khz PWM signal, 400 steps - actually it is working)
| Code: | #include "C:\Documents and Settings\Guest\Desktop\PIC\main.h"
#use fast_io (A)
#use fast_io (C)
long value=0;
int cont=0;
#int_RA
void RA_isr(void)
{
delay_ms (30); // leave out bounces
// increment PWM value
if (input_state(PIN_A0)==1) {
output_toggle(PIN_C3);
if (value<=395) value+=5;
set_pwm1_duty(value);
cont++;
while (input_state(PIN_A0)==1);
}
// zero value
if (input_state(PIN_A1)==1) {
value=0;
set_pwm1_duty(value);
cont++;
while (input_state(PIN_A1)==1);
}
// decrease PWM value
if (input_state(PIN_A2)==1)
{
output_toggle(PIN_C2);
if (value>=5) value-=5;
set_pwm1_duty(value);
cont++;
while (input_state(PIN_A2)==1);
}
}
void main()
{
set_tris_a (0x3F); // all inputs
set_tris_c (0x00); // all outputs
setup_adc_ports(NO_ANALOGS|VSS_VDD);
setup_adc(ADC_OFF);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
// 20KHz PWM with a total of 400 possible steps
setup_timer_2(T2_DIV_BY_1, 99, 1);
setup_ccp1(CCP_PWM);
set_pwm1_duty(value);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
enable_interrupts(INT_RA);
enable_interrupts(GLOBAL);
setup_oscillator(OSC_8MHZ);
while(true) {
delay_ms(1000);
output_c(cont & 0x0F);
}
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Mar 18, 2009 3:58 pm |
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Look at your compiler warnings (or enable them). You should see
this warning:
| Quote: | | Interrupts disabled during call to prevent re-entrancy: (@delay_ms1) |
Read this thread:
http://www.ccsinfo.com/forum/viewtopic.php?t=38151
Adding the line in bold will solve your immediate problem:
| Quote: | #use delay(fill in with your freq)
void main()
{
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Guest
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| Posted: Fri Mar 20, 2009 4:42 pm |
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Exactly! wow, must refine my search routines 
Tnx! |
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