CC3235SF: 关于如何进行配置和使用DMA？

请问我想要使用DMA资源来访问外设数据，我应该如何配置并使用呢？

Kevin Qiu1：

DMA仅供SPI I2S UART等外设使用，这些外设例程中已经配置了DMA

DMA说明参考：https://dev.ti.com/tirex/content/simplelink_cc32xx_sdk_5_30_00_08/docs/drivers/doxygen/html/_u_d_m_a_c_c32_x_x_8h.html

https://dev.ti.com/tirex/content/simplelink_cc32xx_sdk_5_30_00_08/docs/drivers/doxygen/html/index.html

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wu：

我就是使用SPI的时候，但是发现我的SPI没有使用DMA，因为它一直占用着CPU的时间

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Kevin Qiu1：

你用例程直接测试也是这样吗

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wu：

例程没有测试，我不知道例程哪里设置了才算是使用了DMA呢，我看例程代码好像并没有特殊的说明

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Kevin Qiu1：

SPI例程已经内置了DMA程序，可以在sysconfig中看到配置的DMA

参考：https://e2e.ti.com/support/wireless-connectivity/wi-fi-group/wifi/f/wi-fi-forum/729813/ccs-launchcc3220modasf-spi-dma

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wu：

但是我应该怎么配置才能确定已经使用了DMA呢，而且如何证明SPI例程就已经使用了DMA呢？

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wu：

为什么我使用SPI读取数据的时候，程序停在了DMA中断了，应该如何解决呢

程序卡在了这里

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Kevin Qiu1：

DMA错误通常是传入了不正确的指针或者堆栈溢出

https://e2e.ti.com/support/wireless-connectivity/wi-fi-group/wifi/f/wi-fi-forum/984018/cc3220sf-i-use-cc3220sf-chip-after-modifying-the-spi-program-the-program-stops-running-and-returns-to-the-ti-driver-config-file-dma-error-handling-function-abnormal-interrupt-what-is-the-reason

另外注意Data buffers要和 data frame size对齐

SPI data frames can be any size from 4-bits to 32-bits. The SPI data frame size is set in SPI_Params.dataSize passed to SPI_open. The SPICC32XXDMA driver implementation makes assumptions on the element size of the SPI_Transaction txBuf and rxBuf arrays, based on the data frame size. If the data frame size is less than or equal to 8 bits, txBuf and rxBuf are assumed to be arrays of 8-bit uint8_t elements. If the data frame size is greater than 8 bits, but less than or equal to 16 bits, txBuf and rxBuf are assumed to be arrays of 16-bit uint16_t elements. Otherwise, txBuf and rxBuf are assumed to point to 32-bit uint32_t elements.

data frame size
buffer element size

4-8 bits
uint8_t

9-16 bits
uint16_t

17-32 bits
uint32_t

Data buffers in transactions (rxBuf & txBuf) must be address aligned according to the data frame size. For example, if data frame is 9-bit (driver assumes buffers are uint16_t) rxBuf & txBuf must be aligned on a 16-bit address boundary, if data frame is 20-bit (driver assumes buffers are uint32_t) rxBuf & txBuf must be aligned on a 32-bit address boundary.