每天解决一个问题3 ：PIT+EDMA+GPIO=PWM

魅影迷踪 · 发表于 2015-9-16 14:52:34

看到很多人对于实现PIT+EDMA+GPIO=PWM有不成功的问题，下面就讲讲根据官网手册实现的这个功能
首先官网手册有一定的误导性，内容是pit周期性触发pit，却把中断源设置成gpio的。其实应该设置成always on。
第二明明是级联通道5，使能请求却是通道1.当然我的失败地方有很多，比如开了中断却没有清除，导致出错。
将gpio输出成led闪烁。由于设置频率太高，看不出闪烁，导致即使调试成功也没看到闪烁

忘同志们引以为戒，下面是主要代码
typedef struct {
u32 high;
u32 low;
} PLS;

/* Variable *******************************************************************/
PLS pls = {10000000, 60000000};
u32 pin_mask = (1 << 7);

void Pluse_Init(void)
{

PORTB->PCR[7] = PORT_PCR_MUX(1) | PORT_PCR_IRQC(3);
PTB->PDDR |= pin_mask;
PTB->PSOR = pin_mask;

DMAMUX->CHCFG[0] = DMAMUX_CHCFG_SOURCE(50);
DMAMUX->CHCFG[0] |= (DMAMUX_CHCFG_ENBL_MASK | DMAMUX_CHCFG_TRIG_MASK);
//DMAMUX->CHCFG[0] = DMAMUX_CHCFG_SOURCE(0);

PIT->CHANNEL[0].LDVAL = pls.high;
PIT->CHANNEL[0].TCTRL &= ~PIT_TCTRL_TEN_MASK;
PIT->CHANNEL[0].TFLG = PIT_TFLG_TIF_MASK;

DMA0->TCD[0].SADDR = (u32)&pin_mask;
DMA0->TCD[0].SOFF = DMA_SOFF_SOFF(0);
DMA0->TCD[0].ATTR = DMA_ATTR_SSIZE(2) | DMA_ATTR_DSIZE(2);
DMA0->TCD[0].NBYTES_MLOFFNO = DMA_NBYTES_MLOFFNO_NBYTES(4);
DMA0->TCD[0].SLAST = DMA_SLAST_SLAST(0);
DMA0->TCD[0].DADDR = (u32)&PTB->PTOR;
DMA0->TCD[0].DOFF = DMA_DOFF_DOFF(0);
DMA0->TCD[0].DLAST_SGA = DMA_DLAST_SGA_DLASTSGA(0);
DMA0->TCD[0].BITER_ELINKNO = DMA_BITER_ELINKNO_BITER(1);
DMA0->TCD[0].CITER_ELINKNO = DMA_CITER_ELINKNO_CITER(1);
DMA0->CDNE = DMA_CDNE_CDNE(0);
DMA0->TCD[0].CSR = DMA_CSR_MAJORELINK_MASK | DMA_CSR_MAJORLINKCH(5);
DMA0->SERQ = DMA_SERQ_SERQ(0);

DMA0->TCD[5].SADDR = (u32)&pls;
DMA0->TCD[5].SOFF = DMA_SOFF_SOFF(4);
DMA0->TCD[5].ATTR = DMA_ATTR_SSIZE(2) | DMA_ATTR_DSIZE(2);
DMA0->TCD[5].NBYTES_MLOFFNO = DMA_NBYTES_MLOFFNO_NBYTES(4);
DMA0->TCD[5].SLAST = DMA_SLAST_SLAST(-8);
DMA0->TCD[5].DADDR = (u32)&PIT->CHANNEL[0].LDVAL;
DMA0->TCD[5].DOFF = DMA_DOFF_DOFF(0);
DMA0->TCD[5].DLAST_SGA = DMA_DLAST_SGA_DLASTSGA(0);
DMA0->TCD[5].BITER_ELINKNO = DMA_BITER_ELINKNO_BITER(2);
DMA0->TCD[5].CITER_ELINKNO = DMA_BITER_ELINKNO_BITER(2);
DMA0->CDNE = DMA_CDNE_CDNE(1);
DMA0->TCD[5].CSR = 0x00;
DMA0->SERQ = DMA_SERQ_SERQ(5);

PIT->CHANNEL[0].TCTRL |= PIT_TCTRL_TEN_MASK;
PIT->CHANNEL[0].LDVAL = pls.low;

PTB->PTOR = pin_mask;
}

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