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tienchuan
Joined: 25 Aug 2009
Posts: 175
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 Posted: Wed Nov 13, 2013 8:42 am |
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Thanks Ttelmah.
| Code: | | (ccp_delta *( 1/(10MHz)*(4*8*1000) ) ) |
Yes, It it's a remark.
In my project change use crystal 10MHZ so that I must calcualtor this constant.
Oh,I thought failure,, I'm careless when using division to change the code, because I always think division math is slower than multiplication. You pls show me way to calculate time for math operation.
Added, when i test with this code, it has return value when i disconnect pulse clock in CCP1 pin, If true, it must no return value,so that I think need to clear int_ccp1 flag?
here is my full code I changed flow your idea:
| Code: |
#include <16F877A.h>
#fuses HS, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
#use delay(clock=10000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
int8 capture_falling_edge;
int8 got_pulse_width;
int16 ccp_delta;
#int_ccp1
void ccp1_isr(void)
{
static int16 t1_falling_edge;
// If current interrupt is for falling edge.
if(capture_falling_edge)
{
setup_ccp1(CCP_CAPTURE_RE);
capture_falling_edge = FALSE;
t1_falling_edge = CCP_1;
}
else
{
setup_ccp1(CCP_CAPTURE_FE);
capture_falling_edge = TRUE;
ccp_delta = CCP_1 - t1_falling_edge;
got_pulse_width = TRUE;
}
}
//====================================
main()
{
int16 pulse_width_ms;
int16 local_ccp_delta;
got_pulse_width = FALSE;
capture_falling_edge = TRUE;
setup_ccp1(CCP_CAPTURE_FE);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_8 );
enable_interrupts(INT_CCP1);
enable_interrupts(GLOBAL);
while(1)
{
if(got_pulse_width)
{
disable_interrupts(GLOBAL);
local_ccp_delta = ccp_delta;
enable_interrupts(GLOBAL);
pulse_width_ms = (local_ccp_delta * 32) /10000 ;
printf("%lu ms \n\r", pulse_width_ms);
}
delay_ms(500);
}
}
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Ttelmah
Joined: 11 Mar 2010
Posts: 19225
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| Posted: Wed Nov 13, 2013 9:22 am |
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It's not INT_CCP1 that is causing it to display with no input. You are not clearing the flag 'got_pulse_width' when you print.
| Code: |
while(1)
{
if(got_pulse_width)
{
disable_interrupts(GLOBAL);
local_ccp_delta = ccp_delta;
enable_interrupts(GLOBAL);
got_pulse_width=FALSE; //need this or it'll keep printing....
pulse_width_ms = (local_ccp_delta * 32) /10000 ;
printf("%lu ms \n\r", pulse_width_ms);
}
delay_ms(500);
}
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On times, CCS has a table in the manual 'how much time do maths operations take', which can be scaled for different clock rates, but the simplest solution is to just use a pulse output and time the actual duration, or use the stopwatch feature in MPLAB.
There is one problem with *32/10000. The result of *32, won't fit in an int16, so for longer times, the values out the top will be lost (65mSec max). If this matters you'll need to cast to an int32.
Best Wishes |
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tienchuan
Joined: 25 Aug 2009
Posts: 175
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| Posted: Wed Nov 13, 2013 8:34 pm |
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Thanks u, Ttelmah.
Well, It worked 
But it seem has error when i disconnect pulse in CCP1, It has return value???
And is here my code edited follow your comment:
| Code: |
#include <16F877A.h>
#fuses HS, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
#use delay(clock=10000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
int8 capture_falling_edge;
int8 got_pulse_width;
int32 ccp_delta;
#int_ccp1
void ccp1_isr(void)
{
static int16 t1_falling_edge;
// If current interrupt is for falling edge.
if(capture_falling_edge)
{
setup_ccp1(CCP_CAPTURE_RE);
capture_falling_edge = FALSE;
t1_falling_edge = CCP_1;
}
else
{
setup_ccp1(CCP_CAPTURE_FE);
capture_falling_edge = TRUE;
ccp_delta = CCP_1 - t1_falling_edge;
got_pulse_width = TRUE;
}
}
//====================================
main()
{
int32 pulse_width_ms;
int32 local_ccp_delta;
got_pulse_width = FALSE;
capture_falling_edge = TRUE;
setup_ccp1(CCP_CAPTURE_FE);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_8 );
enable_interrupts(INT_CCP1);
enable_interrupts(GLOBAL);
while(1)
{
if(got_pulse_width)
{
disable_interrupts(GLOBAL);
local_ccp_delta = ccp_delta;
enable_interrupts(GLOBAL);
got_pulse_width= FALSE;
pulse_width_ms = (local_ccp_delta * 32) /10000;
printf("%lu ms \n\r", pulse_width_ms);
}
delay_ms(500);
}
}
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Thanks u so much.
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Ttelmah
Joined: 11 Mar 2010
Posts: 19225
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| Posted: Thu Nov 14, 2013 1:28 am |
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No pulse = line floating (unless you have arranged a pull-up resistor). May start picking up RF/mains interference....
Best Wishes |
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tienchuan
Joined: 25 Aug 2009
Posts: 175
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| Posted: Sat Nov 16, 2013 8:05 pm |
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Well, I worked exactly:)
I added config in main code:
Follow instructions in datasheet:
| Quote: | | If the RC2/CCP1 pin is configured as an output, a write to the port can cause a Capture condition |
Thanks u very much
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