PWM

[Ringo]

IS it possible to set up 2 different PWM signals on a pic 16f877?
Tha data sheet says 2 capture/compare/pwm modules, but any example I have found only use 1.
I know to use:
setup_ccp1(CCP_PWM)
setup_timer_2(T2_DIV_BY_1, 127, 1);
set_pwm1_duty(value);

for the first pwm, but what "setup_timer" do I use for the 2nd pwm?
Thanks
___________________________
This message was ported from CCS's old forum
Original Post ID: 2005

[Neutone]

This is from the device file for the 16f877
////////////////////////////////////////////////////////////////// CCP
// CCP Functions: SETUP_CCPx, SET_PWMx_DUTY
// CCP Variables: CCP_x, CCP_x_LOW, CCP_x_HIGH
// Constants used for SETUP_CCPx() are:
#define CCP_OFF 0
#define CCP_CAPTURE_FE 4
#define CCP_CAPTURE_RE 5
#define CCP_CAPTURE_DIV_4 6
#define CCP_CAPTURE_DIV_16 7
#define CCP_COMPARE_SET_ON_MATCH 8
#define CCP_COMPARE_CLR_ON_MATCH 9
#define CCP_COMPARE_INT 0xA
#define CCP_COMPARE_RESET_TIMER 0xB
#define CCP_PWM 0xC
#define CCP_PWM_PLUS_1 0x1c
#define CCP_PWM_PLUS_2 0x2c
#define CCP_PWM_PLUS_3 0x3c
long CCP_1;
#byte CCP_1 = 0x15
#byte CCP_1_LOW= 0x15
#byte CCP_1_HIGH= 0x16
long CCP_2;
#byte CCP_2 = 0x1B
#byte CCP_2_LOW= 0x1B
#byte CCP_2_HIGH= 0x1C


:=IS it possible to set up 2 different PWM signals on a pic 16f877?
:=Tha data sheet says 2 capture/compare/pwm modules, but any example I have found only use 1.
:=I know to use:
:=setup_ccp1(CCP_PWM)
:=setup_timer_2(T2_DIV_BY_1, 127, 1);
:=set_pwm1_duty(value);
:=
:=for the first pwm, but what "setup_timer" do I use for the 2nd pwm?
:=Thanks
___________________________
This message was ported from CCS's old forum
Original Post ID: 2006

[PCM programmer]

:=IS it possible to set up 2 different PWM signals on a pic 16f877?
:=Tha data sheet says 2 capture/compare/pwm modules, but any example I have found only use 1.
:=I know to use:
:=setup_ccp1(CCP_PWM)
:=setup_timer_2(T2_DIV_BY_1, 127, 1);
:=set_pwm1_duty(value);
:=
:=for the first pwm, but what "setup_timer" do I use for the 2nd pwm?

Both PWMs use Timer2. Therefore, they both must have the
same frequency. Each one can have a different duty cycle.

setup_ccp1(CCP_PWM);
setup_ccp2(CCP_PWM);
setup_timer_2(T2_DIV_BY_1, 127, 1);
set_pwm1_duty(value1);
set_pwm2_duty(value2);
___________________________
This message was ported from CCS's old forum
Original Post ID: 2010

[sobak]

I'm trying to produce %50 duty cycle pwm output from RC1/CCP2 on PIC18F8720 and I can do it, I can see with oscilloscope.

but,

when I do that

setup_ccp2(CCP_PWM);

I see my LCD connected to PORTB becomes crazy. I think there is something wrong with RB3/CCP2. I already assigned CCP2 to RC1 usign CONFIG3 register but I see some strange signal (low freq. pulses) on RB3 which is connected to LCD_RS... If I turn off the PWM, it becomes normal....


any idea about what is wrong?

regards

sobak

[Ttelmah]