PWM Synchronization Using Kinetis Flextimers

pliqy666 — Tue, 12 Feb 2019 02:34:03 GMT

你好!
我需要将FTM0和FTM2同步,使用软件触发始终不成功,不知啥原因?代码如下:
   // FTM2 配置
SIM->PINSEL &= ~SIM_PINSEL_FTM2PS2_MASK; // 0  T22--PTC2 PWT_IN0
//SIM->PINSEL |= SIM_PINSEL_FTM2PS2_MASK; // 1  T22--PTC4 PWT_IN0
//SIM->PINSEL |= SIM_PINSEL_FTM2PS3_MASK; //T23--PTC5
SIM->PINSEL &= ~SIM_PINSEL_FTM2PS3_MASK; //T23--PTC3

SIM->SCGC |= SIM_SCGC_FTM2_MASK;
FTM2->SC = 0x0; // CLKS为0，关计数器
//FTM2->CONF |=0xC0; //DBM 11

FTM2->MOD = 959; //50KHz 20*48-1
FTM2->CNTIN=0;
//FTM2->DEADTIME |= 0xF;
FTM2->SC &= ~FTM_SC_CPWMS_MASK; //向上或中心对齐模式选择 ,选向上模式

FTM2->CONTROLS[0].CnV  = 300;
FTM2->CONTROLS[1].CnV  = 600;
FTM2->CONTROLS[2].CnV = 300;
FTM2->CONTROLS[3].CnV = 600;
FTM2->CONTROLS[4].CnV = 0;
FTM2->CONTROLS[5].CnV = 500;
FTM2->CNT=0;
FTM2->SC |= 0x8; //系统时钟，直通

FTM2->SYNCONF |= 0x380; //软件触发
FTM2->SYNC |= 0x4;

void FTM0_Isr(void)
{

FTM2->CONTROLS[4].CnV = 0;
FTM2->CONTROLS[5].CnV = 300;
FTM2->PWMLOAD |=0x200; //使能更新值加载
FTM2->SYNC |= 0x80; //软件触发同步
}
FTM0是计数器为0时发生中断,在中断程序中软件触发FTM2计数器回0,但无法实现.

采用硬件触发方法可行,但为啥会有2微秒左右延时,在变频起点会变化,约0.5微秒左右的摆动,固定频率时没有这个问题.

Re: PWM Synchronization Using Kinetis Flextimers

Robin_Shen — Tue, 26 Feb 2019 09:02:54 GMT

Hi 建雄,

抱歉这么晚才答复你！

我测试了这两种同步方式，但从PWM波形上看同步效果是一样的。

你可以测试以下配置，延迟估计是进中断延迟、中断内语句执行时间、同步延迟。

SIM->SOPT |= SIM_SOPT_FTMSYNC_MASK;   //硬件触发同步
   /*PWM Synchronization Hardware Trigger 2*/
   FTM2->SYNCONF |= FTM_SYNCONF_SYNCMODE_MASK|FTM_SYNCONF_HWRSTCNT_MASK|FTM_SYNCONF_HWWRBUF_MASK;
   FTM2->SYNC |= FTM_SYNC_TRIG2_MASK|FTM_SYNC_REINIT_MASK;

     FTM2->SYNC |= FTM_SYNC_SWSYNC_MASK;   //软件触发同步
    /*PWM Synchronization Software Trigger*/
   FTM2->SYNCONF |= FTM_SYNCONF_SYNCMODE_MASK|FTM_SYNCONF_SWRSTCNT_MASK|FTM_SYNCONF_SWWRBUF_MASK;
   FTM2->SYNC |= FTM_SYNC_SWSYNC_MASK|FTM_SYNC_REINIT_MASK;

不是很清楚你想达到什么效果。如果想要FTM0和FTM2的PWM波形同时开始，还可以试试将FTM2的硬件触发源选择为FTM2 Trigger1（FTM0 CH0 Output）

    /*PWM Synchronization Hardware Trigger 1*/
   FTM2->SYNCONF |= FTM_SYNCONF_SYNCMODE_MASK|FTM_SYNCONF_HWRSTCNT_MASK|FTM_SYNCONF_HWWRBUF_MASK;
   FTM2->SYNC |= FTM_SYNC_TRIG1_MASK|FTM_SYNC_REINIT_MASK;

Best Regards,

Robin

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PWM Synchronization Using Kinetis Flextimers

Re: PWM Synchronization Using Kinetis Flextimers