PIC18, MPLAB X IDE, XC8, PWM, buzzer

PIC18, MPLAB X IDE, XC8, PWM, buzzer

4MHz clock을 통해 Timer2에 4KHz pwm 을 테스트하였습니다.

0. 참고 사항

• [  ] https://openlabpro.com/guide/pulse-width-modulation-using-pic18f4550/
• [  ] http://www.micro-examples.com/public/microex-navig/doc/097-pwm-calculator.html
• [  ] https://www.microchip.com/wwwproducts/en/PIC18F4520
• [ datasheet ] http://ww1.microchip.com/downloads/en/devicedoc/39631a.pdf

1. HW 연결

2. 소스 설명

full 소스는 아래 github를 통해 확인하세요.

Period = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value)             = 4 * 4 * (249 + 1) * 1             = 16 * 250             = 4000Hz Duty Cycle = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale Value)                     = 10bit cycle Delay = 4 * TOSC * (PWM1CON<6:0>) void pwm_Init(unsigned char period){     TRISC2 = 0; // RC2 output         /* CCP PWM mode */     CCP1CON = 0X3C;                       // CCP1CON REGISTER (ECCP1 MODULE, 40/44-PIN DEVICES)                     // P1M1 P1M0 DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0                     // 0     0    1      1     1     1       0       0                     // P1M1:P1M0: Enhanced PWM Output Configuration bits                         // 00 = Single output: P1A modulated; P1B, P1C, P1D assigned as port pins                     // DC1B1:DC1B0: PWM Duty Cycle bit 1 and bit 0                     // CCP1M3:CCP1M0: Enhanced CCP Mode Select bits                         // 1100 = PWM mode; P1A, P1C active-high; P1B, P1D active-high         /* Timer2 configuration */     PR2 = period;           //  configure timer2 period         T2CON=0x04;                 // T2CON: TIMER2 CONTROL REGISTER                 // - T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0                 // 0  0        0          0        0       1       0       0                 // Unimplemented: Read as ?0?                 // T2OUTPS3:T2OUTPS0: Timer2 Output Postscale Select bits                 // TMR2ON: Timer2 On bit                 // T2CKPS1:T2CKPS0: Timer2 Clock Prescale Select bits                     // 00 = Prescaler is 1 }   void pwm_setDuty(unsigned int dutycycle) {     CCPR1L = dutycycle>>2;  //  PWM duty cycle - first 8-bits (MSb)     CCP1CON &= 0xCF;        //  5,4 bits zeroed (DC1B1:DC1B0 = 00)     CCP1CON |= ((dutycycle<<4) & 0x30);  //  PWM duty cycle - last 2-bits (LSb) in CCP1CON 5,4 bits    } void main(void) {     pwm_Init(249);     pwm_setDuty(duty); // 0 ~ 1023     ... }

3. 소스

• https://github.com/sglee0223/pic18/tree/master/pwm_buzzer.X
  

4. 결과

잘 동작하네요