DSP时钟以及QP的TICKS

DSP时钟

1） INTOSC1（10MHz） 
内部时钟源1（INTOSC1），此时钟提供给看门狗块模块，内核和CPU定时器2 。 
时钟频率默认为10MHz，可以通过INTOSCnTRIM寄存器修改频率。 
2） INTOSC2（10MHz） 
功能与INTOSC1是一样的。 
3） 外部晶体振荡器 
使用外部晶体振荡器给芯片提供时钟，晶振连接于X1/X2 脚。 
4） 外部时钟源 
如果不使用外部晶振作为时钟源，可以选择这种模式。时钟从外部时钟源的XCLKIN引脚输入生成。 

 

下图可以看出SPI、SCI、I2C使用低速时钟，EPWM、ECAP、EQEP采用系统时钟、ADC采用高速时钟

步进驱动dsp2806

#define DSP28_CLKINDIV   	0

#define DSP28_PLLCR   		10

void InitSysCtrl(void)
{
	DisableDog();

	InitPll(DSP28_PLLCR, DSP28_CLKINDIV);

	InitPeripheralClocks();
}

选择外部20M晶振，

系统时钟SYSCLKOUT = ( OSCCLK x 10) / div = ( 20 x 10 ) / 2 = 100MHz

平车DSP28034

#define DSP28_DIVSEL   2

#define DSP28_PLLCR   12 

void InitSysCtrl(void)
{

   DisableDog();

   IntOsc1Sel();

   InitPll(DSP28_PLLCR,DSP28_DIVSEL);

   InitPeripheralClocks();
}

选择10MHz内部振荡器1作为时钟

SYSCLKOUT = ( 10 x 12 ) / 2 = 60MHz

SYSCtrlRegs.LOSPCP.all = 0x0002

低速时钟 = 60Mhz / 4 = 15MHz

#define PWMPRD				3000
    
    EPwm2Regs.TBPRD = PWMPRD; 						// Period = 3001 TBCLK counts 20M HZ
	EPwm2Regs.TBPHS.all = 0; 							// Set Phase register to zero
	EPwm2Regs.TBCTR = 0; 							// clear TB counter
	EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN;
	EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE;			// Phase loading enabled
	EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;
	EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
	EPwm2Regs.TBCTL.bit.PHSDIR = TB_UP;				//counts up after syn
	EPwm2Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; 		// TBCLK = SYSCLK
	EPwm2Regs.TBCTL.bit.CLKDIV = TB_DIV1;

	EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
	EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
	EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO_PRD; 	// load on CTR = Zero
	EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO_PRD; 	// load on CTR = Zero
	EPwm2Regs.CMPA.half.CMPA = 1000; 					// Compare A = 350 TBCLK counts
	EPwm2Regs.CMPB = 1500; 							// Compare B = 200 TBCLK counts

	EPwm2Regs.AQCTLA.bit.ZRO = AQ_CLEAR;
	EPwm2Regs.AQCTLA.bit.CAU = AQ_SET;  
	EPwm2Regs.AQCTLA.bit.PRD = AQ_SET;  
	EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR;
	EPwm2Regs.AQCTLB.bit.ZRO = AQ_CLEAR;
	EPwm2Regs.AQCTLB.bit.CBU = AQ_SET;  
	EPwm2Regs.AQCTLB.bit.PRD = AQ_SET;  
	EPwm2Regs.AQCTLB.bit.CBD = AQ_CLEAR;

	EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;	//全部输出打开死区控制
	EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_LOC;		//A输出逻辑低有效
	EPwm2Regs.DBCTL.bit.IN_MODE = DBA_ALL;			//AQ输出A作为死区控制输入
	EPwm2Regs.DBFED = PWM_DeadbandTime;				//死区时间设定
	EPwm2Regs.DBRED = PWM_DeadbandTime;

	EPwm2Regs.TZSEL.bit.OSHT2 = TZ_ENABLE;		//TZ1 One Time Tripper Protect
	EPwm2Regs.TZCTL.bit.TZA = TZ_FORCE_HI;
	EPwm2Regs.TZCTL.bit.TZB = TZ_FORCE_HI;		//Protect State is Forced to Low
	EPwm2Regs.TZEINT.bit.OST = TZ_DISABLE;		//Enable TZ Int
	EPwm2Regs.TZCLR.all = 0x07;					//Clear all int flag

	EPwm2Regs.ETSEL.bit.INTEN = 0;					// Disable EPWM interrupt
	EPwm2Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO;
	EPwm2Regs.ETPS.bit.INTPRD = ET_1ST;				// Generate an interrupt on the first event
	EPwm2Regs.ETCLR.bit.INT = 1;					// Clear spurious interrupt
	EPwm2Regs.ETSEL.bit.INTEN = 1;					// Enable EPWM interrupt

PWM采用系统时钟60MHz，周期3000，采用增减计数模式，在时基计数器值为0是产生中断。因为每6000计数产生一次中断。

中断的中期 = 1 / 60M *6000 = 0.0001(s) = 0.1 (ms) = 100 (us)

PWM的中断内包含QF_tick();，并且每进入10次处理一次。

QF_tick周期为1ms。