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freedom
Joined: 10 Jul 2011
Posts: 54
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| #INT_RTCC based pwm will not work |
 Posted: Tue Nov 17, 2015 7:07 am |
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Hello all
www.ccsinfo.com/forum/viewtopic.php?t=20050&postdays=0&postorder=asc&start=0
| Quote: | They didn't show the setup code for the RTCC, so I've taken the liberty
of making a test program. For a PIC with a 4 MHz crystal, this demo
program creates a PWM signal on Pin B1, with a frequency of 100 Hz,
and a 25% duty cycle |
I am trying to build pulse generator ( software pwm) as per PCM programmer provided code and working fine.
But, when I want to change the pwm rate using a switch control , its not working.
Any idea please ? I am using ver 4.124 and here is my code
| Code: |
#include <16F877A.H>
#device *=16 // Use 16 bit pointers for Full RAM use (for 14 bit parts)
#device adc=10 //Configures the read_adc return size
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 20MHZ) //Crystal Frequency clock
#use fast_io(A) // Port forwarding commands apply to A port
#use fast_io(B) // Port forwarding commands apply to B port
#use fast_io(C) // Port forwarding commands apply to C port
#use fast_io(D) // Port forwarding commands apply to D port
#use fast_io(E) // Port forwarding commands apply to E port
#define Speed_1 PIN_B7
#define Speed_2 PIN_B6
#define Stepper_pulse_out PIN_C1
////==============================================================================
//#define LOOPCNT 39 // PWM Rate
int8 width ;
int8 loopcnt_valu ;
int8 loopcnt ;
//-------------------------------
#INT_RTCC
void tick_interrupt(void);
main()
{
width = 10;
loopcnt_valu = 30; // initial valu
loopcnt = loopcnt_valu ;
set_tris_A(0b000001); // configure input output
set_tris_B(0b11111111);
set_tris_C(0b10100000);
set_tris_D(0b00010000);
set_tris_E(0b000);
setup_timer_0(RTCC_INTERNAL|RTCC_8_BIT|RTCC_DIV_4);
enable_interrupts (INT_TIMER0);
enable_interrupts(global);
set_timer0(6);
while(1)
{
if (input(Speed_1)==0 )
{
loopcnt_valu = 20 ;
}
if (input(Speed_2)==0 )
{
loopcnt_valu = 40 ;
}
}
}
//====================================
#INT_RTCC
void tick_interrupt(void)
{
static int8 loop = LOOPCNT;
static int8 pulse;
if(--loop == 0)
{
loop = LOOPCNT;
pulse = width;
}
if(pulse)
{
output_high(Stepper_pulse_out);
pulse--;
}
else
{
output_low(Stepper_pulse_out);
}
}
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[b]
Last edited by freedom on Tue Nov 17, 2015 9:02 am; edited 2 times in total |
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alan
Joined: 12 Nov 2012
Posts: 357
Location: South Africa
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| Posted: Tue Nov 17, 2015 7:22 am |
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LOOPCNT is zero. Or did you want to use loopcnt_valu instead.
Regards |
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freedom
Joined: 10 Jul 2011
Posts: 54
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| Posted: Tue Nov 17, 2015 8:04 am |
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| Quote: | | LOOPCNT is zero. Or did you want to use loopcnt_valu instead. |
I want to asign the value of LOOPCNT by loopcnt_valu which is generated in while loop if statement
| Code: |
if (input(Speed_1)==0 )
{
loopcnt_valu = 20 ; |
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wangine
Joined: 07 Jul 2009
Posts: 98
Location: Curtea de Arges, Romania
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Nov 17, 2015 8:13 pm |
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The main problem is that you are setting a variable called 'loopcnt_valu'
but you don't use it anywhere else. It's not used in the RTCC routine.
The problem is the lines in bold below:
| Quote: | while(1)
{
if (input(Speed_1)==0 )
{
loopcnt_valu = 20 ;
}
if (input(Speed_2)==0 )
{
loopcnt_valu = 40 ;
}
}
} |
To fix it, remove the '_valu' at the end, as shown below.
| Code: | while(1)
{
if (input(Speed_1)==0 )
{
loopcnt = 20 ;
}
if (input(Speed_2)==0 )
{
loopcnt = 40 ;
}
}
} |
There are a few other problems in your program such as:
1. Using the XT fuse with a 20 MHz crystal ? It won't work anywhere
except in Proteus. Real hardware needs the HS fuse.
2. CCS is not case sensitive by default. This is a strategy mistake in
my opinion. You should not use LOOPCNT and loopcnt in the same
program. It works in CCS, but it's just not good coding style.
3. The compiler warns you about main() and while(1). You can fix these
warnings as shown in bold below:
| Quote: | void main()
{
while(TRUE)
{
} |
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freedom
Joined: 10 Jul 2011
Posts: 54
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| Posted: Tue Nov 17, 2015 11:56 pm |
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Thank Everyone. Now I understand my fault.
Now it is working |
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