我正在尝试为每个对角线使用一个 PWM 发生器（在我的情况下为 PWM1 和 PWM4）来控制 H 桥转换器。
我希望能够同时控制频率和占空比。为此，我在 PWM4 周期开始时生成触发中断，然后更新两个 PWM 通道的周期、相位和占空比寄存器。
问题是，当此更新发生时，一段时间内会出现一些意外行为。见图片。
PWM4 为青色，PWM1 为品红色，当 PWM4 触发中断发生时黄色切换。
PWM1（洋红色）似乎更新为较慢的频率（应该如此），但 PWM4 继续在旧频率上运行另一段时间。PWM1 还会产生一个更短的脉冲。我测量了更新周期、占空比和相位寄存器值所需的时间，大约是 1us，所以这应该不是问题。以下是 PWM 配置：
void PWM4Config() {
ANSELEbits.ANSE6 = 0;
ANSELEbits.ANSE7 = 0;
TRISEbits.TRISE6 = 0;
TRISEbits.TRISE7 = 0;
PTPER = 7002; //period je 50us
PTCON2bits.PCLKDIV = 0b000; //1:1
//fazni stavovi
PHASE4 = 0;
SPHASE4 = 0;
//duty
PDC4 = 3501;
SDC4 = 3501;
//dead time
DTR4 = 0;
//set PWM mode to independent, active high
IOCON4bits.PENH = 1;
IOCON4bits.PENL = 1;
IOCON4bits.POLH = 0;
IOCON4bits.POLL = 0;
IOCON4bits.PMOD = 0b11;
IOCON4bits.OVRENH = 0;
IOCON4bits.OVRENL = 0;
IOCON4bits.OVRDAT = 0b00;
IOCON4bits.FLTDAT = 0b00;
IOCON4bits.CLDAT = 0b00;
IOCON4bits.SWAP = 0;
IOCON4bits.OSYNC = 0;
//set primary time base, edge aligned, independent duty cycles
PWMCON4 = 0x0000;
//PWMCON4bits.IUE = 1; //privremeno
//config faults
FCLCON4 = 0x0003;
//config trigger & interrupt
IFS6bits.PWM4IF = 0;
IEC6bits.PWM4IE = 1;
TRGCON4 = 0x0000; //triger at every period of pwm
TRIG4 = 0x0000; //triger at start of pwm period
PWMCON4bits.TRGIEN = 0;
}
void PWM1Config() {
ANSELEbits.ANSE0 = 0;
ANSELEbits.ANSE1 = 0;
TRISEbits.TRISE0 = 0;
TRISEbits.TRISE1 = 0;
PTPER = 7002; //period je 50us
PTCON2bits.PCLKDIV = 0b000; //1:1
//fazni stavovi
PHASE1 = 3051;
SPHASE1 = 3501;
//duty
PDC1 = 3501;
SDC1 = 3501;
//dead time
DTR1 = 0;
//set PWM mode to independent, active high
IOCON1bits.PENH = 1;
IOCON1bits.PENL = 1;
IOCON1bits.POLH = 0;
IOCON1bits.POLL = 0;
IOCON1bits.PMOD = 0b11;
IOCON1bits.OVRENH = 0;
IOCON1bits.OVRENL = 0;
IOCON1bits.OVRDAT = 0b00;
IOCON1bits.FLTDAT = 0b00;
IOCON1bits.CLDAT = 0b00;
IOCON1bits.SWAP = 0;
IOCON1bits.OSYNC = 0;
//set primary time base, edge aligned, independent duty cycles
PWMCON1 = 0x0000;
//PWMCON1bits.IUE = 1; //privremeno
//config faults
FCLCON1 = 0x0003;
//config trigger & interrupt
//IFS5bits.PWM1IF = 0;
//IEC5bits.PWM1IE = 1;
//TRGCON1 = 0x0000; //triger na svakom periodu pwm-a
//TRIG1 = 0x0000; //triger je na pocetku pwm-a
//PWMCON1bits.TRGIEN = 0;
}
它们被设置为独立模式，使用主时基。