SPC56EL怎么使用FlexPWM DMA功能

你好，
我想使用DMA功能每10个PWM周期重新加载PWM占空比。因此，我配置了FlexPWM子模块0和DMA通道10.一个数组为VAL3寄存器存储了8个不同的值，其占空比从10％到80％不等。

我的DMA通道步骤看起来像这样：

edmaChannelSetup（10，＆安培; dcPWM [0]，＆安培; mcPWM_A。
SUBMOD
[0]。
VAL_3
。
[R
，2,0,1,1,2,8，-16,0,0）;
现在VAL_3寄存器由DMA写入，但始终与最后一个表元素一起写入。如果我将DMA迭代减少到4，那么VAL_3总是从我的表中获取第4个元素的值。我已经使用DMA来重新加载etimer比较值，并且在从表中写入一个元素以将寄存器与每个比较事件进行比较时没有问题。

每次重新加载事件都无法使用表中的下一个元素吗？

另外，我不太确定我是否理解DMA的重载功能。 DMAEN寄存器包含VALDE位。在参考手册中，描述说''这个读/写位在设置RF时启用VALx寄存器的DMA写请求''。这是否意味着我每个VAL寄存器收到一个请求（意味着总共六个）或者是否应该使用该请求用一个DMA通道写入所有VAL寄存器？

最好的祝福，
帕特里克



以下为原文





Hello,
I would like to reload PWM duty cycle every 10 PWM periods using DMA functionality. Therefore I configured FlexPWM subodule 0 and DMA channel 10. An array stores 8 different values for VAL3 register which equal duty cycles from 10%...80%.

My DMA channel step looks like that:

• DMAMUX.
  

• CHCONFIG
  

• [10].
  

• R
  

• = DMA_CHANNEL_ENABLED | DMA_CHANNEL_NTRIGGERED | 12;
  

edmaChannelSetup(10,&dcPWM[0],&mcPWM_A.
SUBMOD
[0].
VAL_3
.
R
,2,0,1,1,2,8,-16,0,0);  
Now VAL_3 register is written by DMA, but always with the last table element. If I reduce the DMA iterations to 4, then VAL_3 always gets the value of 4th element from my table. I already used DMA for reloading eTimer compare values and had no problems with writing one element from a table to compare registers with each compare event.

Is there no way to use the next element from table with every reload event?

Additionally, I am not quite sure if I understand the reload feature with DMA. The DMAEN register include the VALDE bit. In the reference manual, the description says ''This read/write bit enables DMA write requests for the VALx register when RF is set''. Does it mean that I get one request per VAL register (means totally six) or should the request be used to write all VAL registers with one DMA channel?

Best regards,
Patrik