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Problem With Multiple PWM Outputs (PIC18F66K22)

 
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MotoDan



Joined: 30 Dec 2011
Posts: 55

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Problem With Multiple PWM Outputs (PIC18F66K22)
PostPosted: Mon Jan 23, 2012 12:26 pm     Reply with quote
Hello all,

I'm having a little trouble getting all 10 of the available PWM outputs to work on a PIC18F66K22. I've programmed each of the PWM's for a duty cycle ranging from 10% to 100% which corresponds to the PWM channel. This allows me to use my scope to find out which pin a particular PWM shows up on. I also enabled Timers 2, 4, 6, & 8 just to make sure I had a timer associated for each PWM. I'm using the 64 pin TQFP package.

Here's a list of the PWM's that have been verified on the scope:

PWM1 - Pin 33, ECCP1 (not working)
PWM2 - Pin 59, ECCP2 (only when CCP2B3 fuse is set)
PWM3 - Pin 3, ECCP3
PWM4 - Pin 6, CCP4
PWM5 - Pin 8, CCP5
PWM6 - Pin 60, CCP6
PWM7 - Pin 61, CCP7 (not working)
PWM8 - Pin 62, CCP8
PWM9 - Pin 63, CCP9 (not working)
PWM10 - Pin 64, CCP10

So there are three PWMs (1,7,9) that don't work at all. I wrote come code to toggle each of these pins (with PWM disabled) and all but RC1 (pin 29) toggled correctly. RC1 appears to be setup as an input even though I have Port C set to all outputs. I did find a reference to RC1 being shared with another module, but can't seem to set it to an output. Also, when I set the fuse 'CCP2C1', the CCP2 PWM does not appear at RC1.

Thanks in advance for any help.


Here's a snipit of the code. Only the pertinent lines are shown:

Code:

#include <18F66K22.h>
#fuses NOWDT,PROTECT,BROWNOUT,PUT,NODEBUG,NOCPD,CPB,NOMCLR

//#fuses CCP2C1  //selects Pin C1 for CCP2
#fuses CCP2B3  //selects Pin B3 for CCP2

#device *=16
#device HIGH_INTS=TRUE
#device ADC=12

#

#use delay(clock=8000000)   //8 MHz osc

void main()
{   

setup_oscillator(OSC_8MHZ);  // Fosc = 8 MHz

setup_adc(ADC_CLOCK_INTERNAL);
setup_adc_ports(sAN0|VSS_VDD);

set_tris_a(0x01);
set_tris_b(0xff);   
set_tris_c(0x00);   
set_tris_d(0x00);
set_tris_e(0x00);
set_tris_f(0x00);
set_tris_g(0x00);
   
PORTA = 0x01;
PORTB = 0xff;
PORTC = 0;
PORTD = 0;
PORTE = 0;
PORTF = 0;
PORTG = 0;

port_b_pullups (true);

setup_timer_2(T2_DIV_BY_1, 100, 1); // 19.8 kHz
setup_timer_4(T4_DIV_BY_1, 100, 1);
setup_timer_6(T6_DIV_BY_1, 100, 1);
setup_timer_8(T8_DIV_BY_1, 100, 1);

enable_interrupts(INT_TIMER2);
enable_interrupts(INT_TIMER4);
enable_interrupts(INT_TIMER6);
enable_interrupts(INT_TIMER8);
enable_interrupts(GLOBAL);

setup_ccp1(CCP_PWM);
setup_ccp2(CCP_PWM);
setup_ccp3(CCP_PWM);
setup_ccp4(CCP_PWM);
setup_ccp5(CCP_PWM);
setup_ccp6(CCP_PWM);
setup_ccp7(CCP_PWM);
setup_ccp8(CCP_PWM);
setup_ccp9(CCP_PWM);
setup_ccp10(CCP_PWM);

set_pwm1_duty(10);
set_pwm2_duty(20);
set_pwm3_duty(30);
set_pwm4_duty(40);
set_pwm5_duty(50);
set_pwm6_duty(60);
set_pwm7_duty(70);
set_pwm8_duty(80);
set_pwm9_duty(90);
set_pwm10_duty(100);

for (;;);

}
Ttelmah



Joined: 11 Mar 2010
Posts: 19496

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PostPosted: Mon Jan 23, 2012 3:39 pm     Reply with quote
The obvious thing on RC1, is the timer1 oscillator input.
Have you tried configuring timer1, and specifying that it should use the Fosc/4 source?. I'd suggest it is defaulting to using an external source, and this is overriding RC1. If you look at table 12-5, this setting overrides the port pin, whatever TRIS is set to....
Can't see anything obvious on CCP7/9. The way to approach this is to extract the listing snippet setting these up, and verify it is addressing the right registers.

Best Wishes
n-squared



Joined: 03 Oct 2006
Posts: 99

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PostPosted: Wed Jan 25, 2012 11:31 am     Reply with quote
The following code is from a product of mine that runs on PIC18F67K22 and uses PWM 1 through 9:
Code:


void init_system(void)
  {
  output_a(0);
  output_b(0);
  output_c(0);
  output_d(0);
  output_e(0);
  output_f(0);
  output_g(0);
  set_tris_a(0b00000000);
  set_tris_b(0b11001111);
  set_tris_c(0b11011000);
  set_tris_d(0b00000000);
  set_tris_e(0b00000000);
  set_tris_f(0b00000000);
  set_tris_g(0b11100110);

  setup_timer_0(RTCC_INTERNAL|RTCC_DIV_8|RTCC_8_bit);    //1.0 ms overflow
  setup_timer_1(T1_INTERNAL|T3_DIV_BY_4);
  setup_timer_2(T2_DIV_BY_16,255,1);  //512 us overflow, 512 us interrupt
  setup_timer_3(T3_DISABLED|T3_DIV_BY_1);
  setup_timer_4(T4_DIV_BY_16,100,5);

  setup_ccp1(CCP_PWM); set_pwm1_duty(100);
  setup_ccp2(CCP_PWM); set_pwm2_duty(100);
  setup_ccp3(CCP_PWM); set_pwm3_duty(100);
  setup_ccp4(CCP_PWM); set_pwm4_duty(100);
  setup_ccp5(CCP_PWM); set_pwm5_duty(100);
  setup_ccp6(CCP_PWM); set_pwm6_duty(100);
  setup_ccp7(CCP_PWM); set_pwm7_duty(100);
  setup_ccp8(CCP_PWM); set_pwm8_duty(100);
  setup_ccp9(CCP_PWM); set_pwm9_duty(100);
  }



Timer 2 is the default timer for PWM's.
I have a CCP2B3 fuse in the header.
Notice that timer1 is defined as T1_INTERNAL.

Hope this helps.
BR
NN
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