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ccp2 pwm

 
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Byeon woo sung



Joined: 24 Jul 2018
Posts: 1

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ccp2 pwm
PostPosted: Tue Jul 24, 2018 5:50 pm     Reply with quote
I use pic18f65k40.
I would like to get a pwm waveform use ccp2 with rb4 port.
But i can't get waveform. (low signal).
Can you see what's wrong?

Code:
#include <18F65K40.h>
#device ADC = 10
#fuses HS,NOWDT,NOPROTECT,CLKOUT,PPS1WAY
#use delay(clock= 16000000 )
#BYTE PORTE = 0XF8D
#BYTE TRISE = 0XF85

#pin_select CCP2OUT=PIN_E4

void main()
{
    int i= 124;
   
    setup_oscillator(OSC_HFINTRC_16MHZ);
    setup_adc(ADC_CLOCK_DIV_32);
    setup_adc_ports(NO_ANALOGS);
    setup_comparator_1(NC_NC);
    setup_comparator_2(NC_NC);
    setup_comparator_3(NC_NC);
   
    setup_timer_2(T2_DIV_BY_4,250,1);
    setup_ccp2(CCP_PWM);
 
    set_tris_e(0x00);
   
    while(TRUE)
    {
        set_pwm2_duty(i);   
    }
}
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Jul 25, 2018 1:08 am     Reply with quote
This line is the problem:
Quote:
setup_timer_2(T2_DIV_BY_4,250,1);

With the K40 series PICs, you need to specify the clock source as internal:
Code:
setup_timer_2(T2_CLK_INTERNAL | T2_DIV_BY_4, 250, 1);
Ttelmah



Joined: 11 Mar 2010
Posts: 19548

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PostPosted: Wed Jul 25, 2018 1:42 am     Reply with quote
Well done PCM_Programmer.

This is one of those 'caveat' ones. On most of the older PIC16/18 PWM's, the clock source for timer2 is fixed (FOSC/4). No choices. If you look at the diagram for the timer, a direct connection. On the K40 and a few other newer PIC's the timer can be operated from other sources. In this case 9 sources. ZCD_OUT, CLKREF_OUT, SOSC, MFINTOSC, LFINTOSC, HFINTOSC, FOSC, FOSC/4, and an external PIN (PPS selectable). The default 'erased' state, selects one of the combinations that is 'reserved', so the timer won't work...
The T2_CLK_INTERNAL settings selects FOSC/4, giving normal operation.

I must admit to having played with PWM's clocked off an external pin, and it is quite a useful ability. Smile
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