PWM for PIC16f877A

[TeoYX]

Hi all,


I am using PIC16f877A to control 2 PWM outputs, which is RC1 and RC2. Below are the sample program for both PWM:

***************************************************************************************************************************************************
#define fanA RC1
#define fanB RC2

CCP2CON = 0b00001100; //PWM Mode

//PWM frequecy set as 4.88KHz
PR2 = 0xFF; //PWM Period Setting
T2CON = 0b00000101; //Timer2 On, prescale 4

//High Speed
CCPR1L = 255;
delay(5000);

fanA=1;

CCP1CON = 0b00001100; //PWM Mode

//PWM frequecy set as 4.88KHz
PR2 = 0xFF; //PWM Period Setting
T2CON = 0b00000101; //Timer2 On, prescale 4

//High Speed
CCPR2L = 255;
delay(5000);

fanB=1;

***************************************************************************************************************************************************

Here is the connection for the fanA and fanB

PWM Output Connection.JPG (4.32 KiB) Viewed 3477 times

PWM Output Connection.JPG (4.32 KiB) Viewed 3477 times

I measured the voltage output from RC1 and RC2 only get 0.05V only with 255. Is the 255 maximum value for the PWM? Don't it should be output 5V?

Please advice. Thanks a lot.

[robosang]

How about TRISC?

[TeoYX]

TRISC = 0b11011001; where RC1 and RC2 are set to be output.

[robosang]

Can you verify the code and hardware at least can execute program? Have you load the program in to PIC (sorry to ask, but many beginner din load the code)

[ABSF]

I measured the voltage output from RC1 and RC2 only get 0.05V only with 255. Is the 255 maximum value for the PWM? Don't it should be output 5V?

50mV is not enough to make the transistor conduct. What is the voltage at the Collector to Ground?
Something is wrong with your program. Did you try with the sample code from cytron that is used to operate DC motors?

Allen

[TeoYX]

Problem solved. There is circuit connection problem. Haha. Thanks a lot for your reply. Thanks...