How to Program PWM2 in PIC16F877A

-
The following code demonstrate, how to write a program to use internal CCP (capture, compare, and PWM) module to generate pulse width modulation.
Timer-2 is used to provide clock to CCP module, so you can not use Timer-2 for any other purpose if you are using CCP module. PWM is very useful feature to control DC motors. In this example, you learn how to control a DC motor. DC motor operating voltage is +5v and frequency is 2.0 khz. Initially 10% duty cycle is applied at startup of DC motor, after that you can increase duty cycle by pressing PWM increment button and decrease duty cycle by pressing PWM decrement button. The PWM duty cycle is shown on oscilloscope. You can visualize duty cycle on oscilloscope. The code is written in “mikroC PRO for PIC v.5.6.1” IDE and simulation is done with Proteus 8.0 SP0. At the end of code, you can find complete project files for download.


Code in mikroC

// direction signal
sbit PWM2_INC_dir at TRISB.B0;
sbit PWM2_DEC_dir at TRISB.B1;
// bit labels portb
sbit PWM2_INC at PORTB.B0;
sbit PWM2_DEC at PORTB.B1;
void main(void)
{
// min duty cycle 10% ()
unsigned short duty_ratio = 25;
// set direction as input
PWM2_INC_dir = 1;
PWM2_DEC_dir = 1;
// init pwm frequency (Hz)
// pwm2 @ 2khz
PWM2_Init(2000);
// start PWM1
PWM2_Start();
// Set init duty for PWM2
// This function is used to set the duty cycle
// of the PWM. The parameter duty_ratio takes
// values from 0 to 255, ie 0 means 0% ,
// 127 means 50% and 255 means 100% duty cycle.
// 255/100 = 2.55 means step by 1%
PWM2_Set_Duty(duty_ratio);
while(1)
{
// if button on RB0 pressed
if (PWM2_INC == 0)
{
Delay_ms(40);
// increment duty cycle
if(duty_ratio < 255)
duty_ratio++;
// change duty cycle
PWM2_Set_Duty(duty_ratio);
}
// if button on RB1 pressed
if (PWM2_DEC == 0)
{
Delay_ms(40);
// decrement duty cycle
if(duty_ratio > 0)
duty_ratio–;
// change duty cycle
PWM2_Set_Duty(duty_ratio);
}
// slow down change pace a little
Delay_ms(5);
}
}

Download Files

For download “mikroC PRO for PIC” project and “Proteus 8.0” simulation files, click here.

Comments

Post a Comment

Popular posts from this blog

How to Program Parallel Slave Port (PSP) in PIC16F877A

-
Image
The following code demonstrate how to use parallel slave port module. The controller offers a mechanism by which an 8-bit parallel bidirectional data transfer can be achieved between a PIC16F877A and other PSP supporting devices. The PIC16F877A's Port-D and Port-E are used in this data transfer. For this data transfer, Port-D is configured as a parallel slave port (PSP) by setting bit-4 of TRISE Register. The pins of Port-E function as control pins for data transfer. The code is written in “mikroC PRO for PIC v.6.6.3” IDE and simulation is done with Proteus 8.0 SP0. At the end of code, you can find complete project files for download. UUT Code in mikroC // function proto-type void PSP_Setting(void); void main(void) { // portb as input port TRISB = 0xFF; // portc as output port TRISC = 0x00; // portc init to 0x00 PORTC = 0x00; PSP_Setting(); while(1) { // write request to PSP if(TRISE.IBF == 1) { PORTC = PORTD; // auto clear
Read more

How to Program Interrupts in PIC16F877A

-
Image
There are 15 interrupts available in PIC16F877A controller. I will try to demonstrate individual interrupt so that you can easily understand. The list is the following. 1. External Interrupt 2. RB Port Change Interrupt 3. Timer 0 Interrupt 4. Timer 1 Interrupt 5. Parallel Slave Port Read/Write Interrupt 6. A/D Converter Interrupt 7. USART Receive Interrupt 8. USART Transmit Interrupt 9. SPI (Slave) Interrupt 9. Synchronous Serial Port Interrupt 10. CCP1 (Capture, Compare, PWM) Interrupt 11. CCP2  (Capture, Compare, PWM) Interrupt 12. TMR2 to PR2 Match Interrupt 13. Comparator Interrupt 14. EEPROM Write Operation Interrupt 15. Bus Collision Interrupt 1. External Interrupt (RB0) The following code demonstrates how to use external interrupt (RB0). A push button is connected to RB0/INT, when push button is pressed a high to low signal is generated. As in option register external interrupt is configured on falling edge so interrupt is generated and interrupt serv
Read more

How to Program SPI in PIC16F877A (Slave Mode)

-
Image
The following code demonstrate, how to write a program to use SPI (serial peripheral interface) in slave mode. Timer-2 is used to provide clock to SPI module, so you can not use Timer-2 for any other purpose if you are using SPI module. One controller is running in master SPI mode, while the other is running in slave mode. Master send a up counter value to the slave controller. The slave controller receive data and write received data to PORTD. SPI has the four wire interface: SCK (PORTC.3) Serial clock output from master and input to slave [SCK] SDI (PORTC.4) Serial data input to master and output from slave [SDO] SDO (PORTC.5) Serial data output from master and input to slave [SDI] SS (PORTA.5) Slave select active low output from master and input to slave [SS] The SPI data is monitored on SPI debuger and also all signals are displayed on oscilloscope. The code is written in “mikroC PRO for PIC v.5.6.1” IDE and simulation is done with Proteus 8.0 SP0. At the end of code, you
Read more