DMA可以从外设到外设吗？

qq153471503

如题，DAM可以从外设到外设吗？比如ADC采集，串口发送到PC端，不知道能不能行，如果行应该怎么配置？

lycreturn

不能直接外设到外设，你这个可以用2个DMA的方式：ADC到内存，内存到UART

qq153471503

自己顶一下

qq153471503

K.O.Carnivist

lycreturn 发表于 2016-8-12 20:43
不能直接外设到外设，你这个可以用2个DMA的方式：ADC到内存，内存到UART

呃实际上这个是可以的啊。
和外设到内存是一样的设置，但目标地址写外设寄存器。

这段程序是在 F103 上设置 USART2 在 PA2 脚做 Tx；TIM2 每秒溢出一次，级联 TIM3（TIM3每秒向上计数一次），同时 TIM2 溢出时触发 DMA1 从 TIM3->CNT 到 USART2->DR 传输一个字节。
我是在 Nucleo 上做的，连电脑可以看到每秒收到一个字符。



[mw_shl_code=cpp,true]#include "stm32f10x.h"

TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
DMA_InitTypeDef DMA_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;

int main (void)
{
    /* System clocks configuration ---------------------------------------------*/
    /* TIM2, TIM3 and USART2 clock enable */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 | RCC_APB1Periph_TIM3 | RCC_APB1Periph_USART2, ENABLE);
    /* GPIOA clock enable */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
    /* Enable DMA1 clock */
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

    /* Configure USART2 Tx as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    /* USART2 configured as follow:
        - BaudRate = 115200 baud  
        - Word Length = 8 Bits
        - One Stop Bit
        - No parity
        - Transmit enabled
    */
    USART_InitStructure.USART_BaudRate = 115200;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Tx;
    USART_Init(USART2, &USART_InitStructure);
  
    /* Enable the USART2 */
    USART_Cmd(USART2, ENABLE);

    /* TIM2 is configured as Master Timer:
        - The TIM2 Update event is used as Trigger Output  
       TIM3 is slave for TIM2,
        - The ITR1(TIM2) is used as input trigger
        - Gated mode is used, so start and stop of slave counter are
          controlled by the Master trigger output signal(TIM2 update event).
    */

    /* Time base configuration */
    TIM_TimeBaseStructure.TIM_Period = SystemCoreClock / 5000;
    TIM_TimeBaseStructure.TIM_Prescaler = 5000;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    TIM_TimeBaseStructure.TIM_Period = 'z';
    TIM_TimeBaseStructure.TIM_Prescaler = 0;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    /* Select the Master Slave Mode */
    TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable);

    /* Master Mode selection */
    TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);

    /* Slave Mode selection: TIM3 */
    TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Gated);
    TIM_SelectInputTrigger(TIM3, TIM_TS_ITR1);

    /* TIM2 Update DMA Request enable */
    TIM_DMACmd(TIM2, TIM_DMA_Update, ENABLE);

    /* TIM enable counter */
    TIM_SetCounter(TIM3, ' ');
    TIM_Cmd(TIM3, ENABLE);
    TIM_Cmd(TIM2, ENABLE);

    /* DMA1 channel1 configuration ----------------------------------------------*/
    DMA_DeInit(DMA1_Channel2);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(TIM3->CNT);
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&(USART2->DR);
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
    DMA_InitStructure.DMA_BufferSize = 1;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel2, &DMA_InitStructure);
  
    /* Enable DMA1 channel1 */
    DMA_Cmd(DMA1_Channel2, ENABLE);

    while(1);
}[/mw_shl_code]

lycreturn

K.O.Carnivist 发表于 2016-8-17 14:59
呃实际上这个是可以的啊。
和外设到内存是一样的设置，但目标地址写外设寄存器。

看来stm32参考手册有些问题，测试确实可用，实践出真知！ LS做得很好。