DMA的SPI传输问题

天才少年

使用STM32F405，用了两个SPI接口，其中SPI1配置成16位，SPI2配置成8位，请问怎么可以使用DMA将SPI1_RX（16BIT）传输给SPI2_TX（8BIT）？

styleno1

小端碰到类似的数据转换很不方便。

正点原子

帮顶....

天才少年

使用DMA1_Stream4->AR = &(USART1->DR);写DMA的外设地址发现报错，error:  #513: a value of type "volatile uint16_t *" cannot be assigned to an entity of type "uint32_t"

看了一下DMA的外设地址和SPI、USART的数据寄存器发现个问题，DMA的外设地址定义的是__IO uint32_t类型，SPI和USART的数据寄存器定义的是__IO uint16_t类型。我用的4.72a版本的keil，本来都是32位的寄存器，这个版本里面在

stm32f4xx.h里面把那些高位没用的Reserved都独立出来了。这样当要向DMA外设地址写入地址时只能根据头文件一步一步计算了，不知大家还有什么好方法？下面是头文件里面的定义。

[mw_shl_code=c,true]typedef struct { __IO uint32_t CR; /*!< DMA stream x configuration register */ __IO uint32_t NDTR; /*!< DMA stream x number of data register */ __IO uint32_t PAR; /*!< DMA stream x peripheral address register */ __IO uint32_t M0AR; /*!< DMA stream x memory 0 address register */ __IO uint32_t M1AR; /*!< DMA stream x memory 1 address register */ __IO uint32_t FCR; /*!< DMA stream x FIFO control register */ } DMA_Stream_TypeDef; typedef struct { __IO uint32_t LISR; /*!< DMA low interrupt status register, Address offset: 0x00 */ __IO uint32_t HISR; /*!< DMA high interrupt status register, Address offset: 0x04 */ __IO uint32_t LIFCR; /*!< DMA low interrupt flag clear register, Address offset: 0x08 */ __IO uint32_t HIFCR; /*!< DMA high interrupt flag clear register, Address offset: 0x0C */ } DMA_TypeDef;[/mw_shl_code]

[mw_shl_code=c,true]typedef struct { __IO uint16_t CR1; /*!< SPI control register 1 (not used in I2S mode), Address offset: 0x00 */ uint16_t RESERVED0; /*!< Reserved, 0x02 */ __IO uint16_t CR2; /*!< SPI control register 2, Address offset: 0x04 */ uint16_t RESERVED1; /*!< Reserved, 0x06 */ __IO uint16_t SR; /*!< SPI status register, Address offset: 0x08 */ uint16_t RESERVED2; /*!< Reserved, 0x0A */ __IO uint16_t DR; /*!< SPI data register, Address offset: 0x0C */ uint16_t RESERVED3; /*!< Reserved, 0x0E */ __IO uint16_t CRCPR; /*!< SPI CRC polynomial register (not used in I2S mode), Address offset: 0x10 */ uint16_t RESERVED4; /*!< Reserved, 0x12 */ __IO uint16_t RXCRCR; /*!< SPI RX CRC register (not used in I2S mode), Address offset: 0x14 */ uint16_t RESERVED5; /*!< Reserved, 0x16 */ __IO uint16_t TXCRCR; /*!< SPI TX CRC register (not used in I2S mode), Address offset: 0x18 */ uint16_t RESERVED6; /*!< Reserved, 0x1A */ __IO uint16_t I2SCFGR; /*!< SPI_I2S configuration register, Address offset: 0x1C */ uint16_t RESERVED7; /*!< Reserved, 0x1E */ __IO uint16_t I2SPR; /*!< SPI_I2S prescaler register, Address offset: 0x20 */ uint16_t RESERVED8; /*!< Reserved, 0x22 */ } SPI_TypeDef;[/mw_shl_code]

[mw_shl_code=c,true]typedef struct { __IO uint16_t SR; /*!< USART Status register, Address offset: 0x00 */ uint16_t RESERVED0; /*!< Reserved, 0x02 */ __IO uint16_t DR; /*!< USART Data register, Address offset: 0x04 */ uint16_t RESERVED1; /*!< Reserved, 0x06 */ __IO uint16_t BRR; /*!< USART Baud rate register, Address offset: 0x08 */ uint16_t RESERVED2; /*!< Reserved, 0x0A */ __IO uint16_t CR1; /*!< USART Control register 1, Address offset: 0x0C */ uint16_t RESERVED3; /*!< Reserved, 0x0E */ __IO uint16_t CR2; /*!< USART Control register 2, Address offset: 0x10 */ uint16_t RESERVED4; /*!< Reserved, 0x12 */ __IO uint16_t CR3; /*!< USART Control register 3, Address offset: 0x14 */ uint16_t RESERVED5; /*!< Reserved, 0x16 */ __IO uint16_t GTPR; /*!< USART Guard time and prescaler register, Address offset: 0x18 */ uint16_t RESERVED6; /*!< Reserved, 0x1A */ } USART_TypeDef;[/mw_shl_code]

aozima

如果仅是修正编译错误：

[mw_shl_code=c,true]DMA1_Stream4->AR = (uint32_t)&((USART1->DR));[/mw_shl_code]

问题是DMA支持外设到外设吗？
即使支持，两边SPI的DMA谁触发谁？8位到16位又如何转换，直接扔掉？

常规的通用办法是：  外设1 --> DMA1 --> buffer（SRAM） --> DMA2 --> 外设2