The Due has built in complimentary PWM - no external components needed. It can give you 16-bit duty cycle control, dead time control and much more.
I've done some register level programming and set up 4 PWM signals complete with their inverted signals.
You'll find them on pins P34, P35, P36, P37, P38, P39, P40, P41. The PWM frequency is 1.281 KHz.
It's easy to control these signals by changing appropriate values in this sketch (please refer to the datasheet for changing other PWM parameters).
//declare variables
unsigned short duty0 = 15000;
unsigned short duty1 = 30000;
unsigned short duty2 = 45000;
unsigned short duty3 = 60000;
void setup() {
pwmc_setup();
}
void loop() {
pwmc_duty(duty0, duty1, duty2, duty3);
}
void pwmc_setup()
{
//Configure PWM channels 0,1,2,3 (PWML0,PWMH0,PWML1,PWMH1,PWML2,PWMH2,PWML3,PWMH3), (port C.2,C.3,C.4,C.5,C.6,C.7,C.8,C.9), (pins P34,P35,P36,P37,P38,P39,P40,P41)
REG_PIOC_PDR = 0x3FC; //B1111111100, PIO Disable Register
REG_PIOC_ABSR = REG_PIOC_ABSR | 0x3FCu; //B1111111100, Peripheral AB Select Register
REG_PMC_PCER1 = REG_PMC_PCER1 | 16; //Peripheral Clock Enable Register 1 (activate clock for PWM, id36, bit5 of PMC_PCSR1)
REG_PWM_ENA = REG_PWM_SR | B1111; //PWM Enable Register | PWM Status Register (activate channels 0,1,2,3)
REG_PWM_CMR0 = 0x10000; //Channe0 Mode Register: Dead Time Enable DTE=1
REG_PWM_CMR1 = 0x10000; //Channe1 Mode Register: Dead Time Enable DTE=1
REG_PWM_CMR2 = 0x10000; //Channe2 Mode Register: Dead Time Enable DTE=1
REG_PWM_CMR3 = 0x10000; //Channe3 Mode Register: Dead Time Enable DTE=1
REG_PWM_DT0 = 0xA800A8; //Channe0 Dead Time Register (168=2us for outputs PWML0,PWMH0)
REG_PWM_DT1 = 0xA800A8; //Channe1 Dead Time Register (168=2us for outputs PWML1,PWMH1)
REG_PWM_DT2 = 0xA800A8; //Channe2 Dead Time Register (168=2us for outputs PWML2,PWMH2)
REG_PWM_DT3 = 0xA800A8; //Channe3 Dead Time Register (168=2us for outputs PWML3,PWMH3)
REG_PWM_CPRD0 = 65535; //Channe0 Period Register (84mhz/65535=1.281khz=780.64us period)
REG_PWM_CPRD1 = 65535; //Channe1 Period Register (84mhz/65535=1.281khz=780.64us period)
REG_PWM_CPRD2 = 65535; //Channe2 Period Register (84mhz/65535=1.281khz=780.64us period)
REG_PWM_CPRD3 = 65535; //Channe3 Period Register (84mhz/65535=1.281khz=780.64us period)
}
//Set the PWM duty-cycle
inline void pwmc_duty(unsigned short duty0, unsigned short duty1, unsigned short duty2, unsigned short duty3) {
REG_PWM_CDTY0 = duty0;
REG_PWM_CDTY1 = duty1;
REG_PWM_CDTY2 = duty2;
REG_PWM_CDTY3 = duty3;
}
