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chinukis
Joined: 05 Nov 2012
Posts: 4
Location: United States
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| 24FV32KA301 PWM freq. not works |
 Posted: Mon Nov 05, 2012 8:19 pm |
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How can I get to 320Khz PWM with this chip? The most I can get is 243hz and I had try many combinations, I use a 20Mhz external crystal.
| Code: |
#include <24FV32KA301.h>
#device ICD=TRUE
#INCLUDE <string.h>
#INCLUDE <ctype.h>
//Primary Oscillator with PLL
#FUSES NOWDT
#FUSES CKSFSM //Clock Switching is enabled, fail Safe clock monitor is enabled
#FUSES WDT_NOSL //Watch Dog Timer, disabled during SLEEP
#FUSES NOBROWNOUT //No brownout reset
//#use delay(crystal=20000000)
#use delay(internal=32Mhz)
//#pragma use rs232(UART1,baud=9600,xmit=PIN_B7,rcv=PIN_B2,parity=N,bits=8,ERRORS,RESTART_WDT,stream=COM1)
//#pragma use rs232(UART1,baud=9600,xmit=PIN_B7,rcv=PIN_B2,parity=N,bits=8,ERRORS,RESTART_WDT,stream=COM1)
//#pragma use rs232(UART2,baud=115200,xmit=PIN_B0,rcv=PIN_B1,parity=N,bits=8,ERRORS,RESTART_WDT,stream=COM2)
//#define BUFFER_SIZE 240
//#define BUFFER_SIZE3 70
//#define BUFFER_SIZE2 240
//BYTE buffer_1[BUFFER_SIZE];
//BYTE buffer_3[BUFFER_SIZE3];
//BYTE next_in_1 = 0;
//BYTE next_out_1 = 0;
// buffer_2[BUFFER_SIZE2];
//BYTE next_in_2 = 0;
//BYTE next_out_2 = 0;
//int tam=0;
/////////////////////////////////////////////////////////////////////////
// //
/////////////////////////////////////////////////////////////////////////
void main() {
int16 duty;
int16 value=32768L;
duty = 0;
setup_timer2(TMR_INTERNAL | TMR_DIV_BY_1,39);
setup_compare(1, COMPARE_PWM_EDGE | COMPARE_TIMER2);
While(1){
if(!input(PIN_B1)){
delay_ms(330);
if(!input(PIN_B1))
value=value+1000;
}
if(!input(PIN_B2)){
delay_ms(300);
if(!input(PIN_B2))
value=value-1000;
}
duty= value ;
set_pwm_duty(1, duty);
}
}
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With this configuration I alway have 240 Hz, if I use external crystal, freq. is always 150 hz.
How can I modify freq. to obtain 320 Hz ?
setup_timer2(TMR_INTERNAL | TMR_DIV_BY_1,39); no works period, i change value but always have 240 hz.
Thanks |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Nov 06, 2012 3:09 am |
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I'm confused, about what frequencies you are using and trying to generate.
| Quote: | How can I get to 320Khz PWM with this chip? The most I can get is 243hz and I had try many combinations, I use a 20Mhz external crystal.
Code:
...
#use delay(internal=32Mhz)
setup_timer2(TMR_INTERNAL | TMR_DIV_BY_1,39);
With this configuration I alway have 240 Hz, if I use external crystal, freq. is always 150 hz.
How can I modify freq. to obtain 320 Hz ?
setup_timer2(TMR_INTERNAL | TMR_DIV_BY_1,39); no works period, i change value but always have 240 hz. |
You're:-
1) Asking for 320kHz, then 320Hz.
2) Quoting 20MHz crystal then using 32Mz for delay.
Is your crystal working properly?
Does an LED flasher work at the correct frequency?
Seriously, are you wanting kHz or Hz?
Mike
EDIT And, of course, complier version No. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19358
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| Posted: Tue Nov 06, 2012 4:05 am |
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Also:
You continually update the duty cycle, even if the value hasn't changed.
What is the maximum period with your clock and PWM frequency (equation 15-3 in the data sheet)?. Divider required is 49, and you have just 5.6bits of resolution. Maximum period value of just 50, but you are using 32767, and updating in thousands.....
Best Wishes |
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chinukis
Joined: 05 Nov 2012
Posts: 4
Location: United States
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| Posted: Tue Nov 06, 2012 10:52 am |
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Thanks for your help.
About frequency, I need 320 Hz,
I'm using 20MHz crystal,
Ver.4.134 CCS compiler
About 20Mhz and 32Mhz,
I use internal 32MHz because with 20 MHz I only get 150 Hz.
I follows equation and nothing, that is the reason for the period value. I was playing with numbers, because nothing seems to work.
The duty cycle is in a loop because I use input B1 and B2 to increase and decrease duty. |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Nov 06, 2012 12:05 pm |
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Work on the KISS principle.
Remove surplus code (RS232 etc).
Start with a LED flasher. Confirm this works at the correct frequency.
Then try PWM at a fixed frequency and sensible fixed duty cycle (i.e. LESS than the period).
Learn to walk before attempting to run with push buttons.
Mike |
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chinukis
Joined: 05 Nov 2012
Posts: 4
Location: United States
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| Posted: Tue Nov 06, 2012 1:58 pm |
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Thanks for the tip
But dosent works
| Code: | #include <24FV32KA301.h>
#device ICD=TRUE
//Primary Oscillator with PLL
#FUSES NOWDT
#FUSES CKSFSM //Clock Switching is enabled, fail Safe clock monitor is enabled
#FUSES WDT_NOSL //Watch Dog Timer, disabled during SLEEP
#FUSES NOBROWNOUT //No brownout reset
#use delay(crystal=20000000)
//////////////////////////////////
void main() {
setup_compare(1, COMPARE_PWM_EDGE | COMPARE_TIMER2);
setup_timer2(TMR_INTERNAL | TMR_DIV_BY_1,225);
set_pwm_duty(1, 122);
While(1);
} |
With this configuration, always have 150 Hz, |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19358
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| Posted: Tue Nov 06, 2012 3:32 pm |
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You are not actually turning on the primary oscillator. Since you have fail safe mode enabled, it is dropping back to the secondary, which is giving you 62.5KHz. 62500/(2*226) = 138Hz.
#fuses HS
Best Wishes |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Nov 06, 2012 3:37 pm |
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Have you tried and tested a simple LED flasher?
What duty ratio are you getting?
What happens if you change your programmed duty ratio?
Mike |
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chinukis
Joined: 05 Nov 2012
Posts: 4
Location: United States
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| Posted: Tue Nov 06, 2012 5:28 pm |
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Hi,
Also i use #fuses HS and nothing
duty is not a problem, but you need to use more than 255,
i use it from 0 to 65535 to get 0 to 100 % duty cycle |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Nov 06, 2012 5:55 pm |
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We're trying to help you, but you're still not clearly answering the questions.
It's bed time here.
Bye
Mike |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19358
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| Posted: Wed Nov 07, 2012 3:40 am |
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| chinukis wrote: |
set_pwm_duty(1, 122L);
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Seriously, take the hint, that has been given multiple times. Run a simple 'three line LED flasher', and verify the frequency of this, _before_ trying to use the PWM. You _must_ repeat _must_ get your clock working and know that it is working at the right rate, before trying to get the PWM going. You are trying to 'walk before you can crawl'.
Best Wishes |
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