書沒有看清楚，再詳看一下 dsPIC30F Family Reference Manual 裡的 MCPWM 章節。http://www.microchip.com/stellent/gro ... ts/devicedoc/en026096.pdf

有幾個戰存器是要了解的:
PTCON : PWM Time Base Control register
PTMR : PWM Time Base counter
PTPER : PWM Time Base Period register
SEVTCMP : PWM Special Event Compare register
PWMCON1 : PWM Control register #1
PWMCON2 : PWM Control register #2
DTCON1: Dead Time Control register #1
DTCON2: Dead Time Control register #2
FLTACON : Fault A Control register
FLTBCON : Fault B Control register
PDCx : PWM Duty Cycle register #1 ~ #4

控制 Period 的就是 PTPER 暫存器。
控制 Duty Cycle 的是PDC1, PDC2, PDC3 三個暫存器，看底下波形應可知道。

Attach file:

---

  (0.00 KB)


  (0.00 KB)

以下程式碼為曾百由寫的 dspic數位訊號控制器原理與應用
第15章中的範例

//---------------------------------------------------------------------
#define __dsPIC30F4011__

#include <p30F4011.h>
#include <pwm.h> // 將pwm函式的原型宣告檔案含入

#define FCY 7372800 * 2 // 因為使用頻率為將外部 7.3728 MHz * 8 的模式 , 每一指令週期需 4 個 clock
// 所以 FCY = (7.3728 * 8 / 4 ) MHz = 7372800* 2

void Init_MCPWM(void);

_FOSC(CSW_FSCM_OFF & XT_PLL8); //XT with 8xPLL oscillator, Failsafe clock off
_FWDT(WDT_OFF); //Watchdog timer disabled
_FBORPOR(PBOR_OFF & MCLR_EN); //Brown-out reset disabled, MCLR reset enabled
_FGS(CODE_PROT_OFF); //Code protect disabled


int main(void)
{

Init_MCPWM( );

while(1);
}

void Init_MCPWM(void)
{
/* Holds the PWM interrupt configuration value*/
unsigned int config;
/* Holds the value to be loaded into dutycycle register */
unsigned int period;
/* Holds the value to be loaded into special event compare register */
unsigned int sptime;
/* Holds PWM configuration value */
unsigned int config1;
/* Holds the value be loaded into PWMCON1 register */
unsigned int config2;
/* Holds the value to configure the special event trigger postscale and dutycycle */
unsigned int config3;
/* The value of ‘dutycyclereg’ determines the duty cycle register(PDCx) to be written */
unsigned int dutycyclereg;
unsigned int dutycycle;
unsigned char updatedisable;
/* Configure pwm interrupt enable/disable and set interrupt priorties */
config = (PWM_INT_DIS & PWM_FLTA_DIS_INT & PWM_INT_PR1
& PWM_FLTA_INT_PR0);
ConfigIntMCPWM( config );
/* Configure PWM to generate square wave of 50% duty cycle */
dutycyclereg = 1;
dutycycle = 0x3FFF;
updatedisable = 0;
SetDCMCPWM(dutycyclereg,dutycycle,updatedisable);
period = 0x7fff;
sptime = 0x0;
config1 = (PWM_EN & PWM_IDLE_STOP & PWM_OP_SCALE16
& PWM_IPCLK_SCALE64 &
PWM_MOD_UPDN);
config2 = (PWM_MOD1_COMP &
PWM_PDIS3H & PWM_PDIS2H & PWM_PEN1H &
PWM_PDIS3L & PWM_PDIS2L & PWM_PEN1L);
config3 = (PWM_SEVOPS1 & PWM_OSYNC_PWM & PWM_UEN);
OpenMCPWM(period,sptime,config1,config2,config3);


/---------------------------------------------------------------/

因為要控制伺服機，他的控訊號是1ms為反轉、2ms為正轉，每秒可接收60個訊號，想請問要怎麼設定 dutycycle 及 period？