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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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 Posted: Wed May 12, 2010 12:46 pm |
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You could write directly to the PWM1CON register, or you could make
a little function to do it. Example:
| Code: |
// Call this routine to set the PWM deadband.
// The deadband value can be from 0 to 127,
// and is in units of Instruction Cycles (Fosc/4).
// For example, with a 4 MHz crystal, an instruction
// cycle is 1 us.
void set_deadband(int8 deadband)
{
#byte PWM1CON = 0x9B
if(deadband > 127) // Do a limit check on the value.
deadband == 127;
PWM1CON = deadband;
}
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This function should be called after you call the setup_ccp1()
function. |
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meereck
Joined: 09 Nov 2006
Posts: 173
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| Posted: Sat May 15, 2010 3:49 pm |
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I am writing a test program for 16F1826.
I might have misunderstood something but the device header file does not contain any definitions for CCP_PULSE_STEERING_A or similar keywords.
I don't think setting TRIS register is enough to get the PWM signal on P1A, P1B, P1C and P1D.
Is it a wrong .h file? Can I copy those declarations from another .h file?
v4.106
cheers |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat May 15, 2010 4:51 pm |
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If it's not in the .h file, CCS may not support it yet. These are new PICs.
I'll check on a work-around for you later. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon May 17, 2010 2:41 pm |
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I don't have a 16F1826 to test, but I think the following work-around code
may work. In the test program shown below, after you call setup_ccp1()
you just call set_pulse_steering() function. Use the constants shown
below to select which channels (P1A, P1B, P1C, P1D) you want to use
for PWM output. I compiled this with vs. 4.107.
| Code: |
#include <16F1826.h>
#fuses INTRC_IO, NOWDT, PUT, NOLVP
#use delay(clock=4000000)
// These are the default PWM output pins for the 16F1826.
// Note: Alternate pins are available for P1A, P1C, P1D
// by setting bits in the APFCON0 register.
#define P1A PIN_B3 // Alternate is Pin B0
#define P1B PIN_B5 // No alernate pin
#define P1C PIN_B6 // Alternate is Pin A7
#define P1D PIN_B7 // Alternate is Pin A6
// Constants for Pulse Steering.
#define CCP_PULSE_STEERING_A 0x01000000
#define CCP_PULSE_STEERING_B 0x02000000
#define CCP_PULSE_STEERING_C 0x04000000
#define CCP_PULSE_STEERING_D 0x08000000
#define CCP_PULSE_STEERING_SYNC 0x10000000
// Call this routine to set the PWM steering. You can OR
// together the PWM steering constants from the PIC's
// header file. (In this case, use the constants shown
// above, since the header file doesn't have them).
void set_pulse_steering(int32 steering)
{
int8 temp;
#byte PSTR1CON = 0x296
temp = make8(steering, 3); // Get high byte only
PSTR1CON = temp; // Setup PWM steering register
// Set the TRIS to outputs for the enabled steering pins.
// Also set the selected pins to a low level.
if(temp & 1)
output_low(P1A);
if(temp & 2)
output_low(P1B);
if(temp & 4)
output_low(P1C);
if(temp & 8)
output_low(P1D);
}
//===========================================
void main()
{
setup_timer_2(T2_DIV_BY_16, 124, 1); // Set 1000 Hz PWM freq
set_pwm1_duty(31); // Set PWM for 25% duty cycle
// Set up PWM so that all four outputs are active high.
setup_ccp1(CCP_PWM_H_H);
// Enable PWM output on all four pins.
set_pulse_steering( CCP_PULSE_STEERING_A |
CCP_PULSE_STEERING_B |
CCP_PULSE_STEERING_C |
CCP_PULSE_STEERING_D);
while(1);
} |
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meereck
Joined: 09 Nov 2006
Posts: 173
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| Posted: Tue May 18, 2010 2:05 am |
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thanks a lot,
I am gonna test it out during the weekend.
Cheers
Meereck |
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