// Timer-triggered memory-to-memory DMA transfer demonstrator for STM32F4xx (probably good enough for STM32F2xx too)// Note, that we won't use the memory-to-memory mode here, as that would simply run not waiting for the triggers// To be run in debugger, watching the dst array to being gradually filled, one word each time the trigger reloads//   (and perhaps watching a cycle-counter to see how the timer's ARR setting influences the total time)// (C)2014 by wek at efton dot sk// Legalese: do whatever you want with this#include "stm32f4xx.h"#include 
     
      #define TIMER 1#if (TIMER == 1)  #define _DMA_     2  #define _Stream_  5  #define _Channel_ 6#elif (TIMER == 2)  // this won't work, as DMA1 can't transfer  #define _DMA_     1  #define _Stream_  1  #define _Channel_ 3#else  #error "no such"#endif#define GLUE5_(a, b, c, d, e) a ## b ## c ## d ## e#define GLUE5(a, b, c, d, e) GLUE5_(a, b, c, d, e)#define GLUE4(a, b, c, d) GLUE5_(a, b, c, d, )#define DBGMCU_APBxFZ GLUE4(DBGMCU->APB, _DMA_, FZ, )#define DBGMCU_APB1_FZ_DBG_TIMy_STOP GLUE4(DBGMCU_APB1_FZ_DBG_TIM, TIMER, _STOP, )#define RCC_AHB1ENR_DMAxEN GLUE4(RCC_AHB1ENR_DMA, _DMA_, EN, )#define DMAx GLUE4(DMA, _DMA_, , )#define DMAStream GLUE4(DMA, _DMA_, _Stream, _Stream_)#if (_Stream_ < 4)  #define yISR LISR#else  #define yISR HISR#endif#define DMA_yISR_TCIFz GLUE4(DMA_, yISR, _TCIF, _Stream_)#define TIMz GLUE4(TIM, TIMER, , )#define APBxENR GLUE4(APB, _DMA_, ENR, )#define RCC_APBxENR_TIMzEN GLUE5(RCC_APB, _DMA_, ENR_TIM, TIMER, EN)#define BUFSIZE 10volatile uint32_t src[BUFSIZE] = {
   1, 2, 3, 4, 5, 6, 7, 8, 9, 10};volatile uint32_t dst[BUFSIZE];int main(void) {//  DBGMCU->APB2FZ |= DBGMCU_APB1_FZ_DBG_TIM1_STOP;  DBGMCU_APBxFZ |= DBGMCU_APB1_FZ_DBG_TIMy_STOP;// TIM1_UP -> DMA2 Stream5 Channel6    RCC->AHB1ENR |= RCC_AHB1ENR_DMAxEN;    while (!(RCC->AHB1ENR & RCC_AHB1ENR_DMAxEN));    DMAStream->NDTR = BUFSIZE;  // halfwords to transfer    DMAStream->M0AR = (uint32_t)src;    DMAStream->PAR = (uint32_t)dst;    DMAStream->FCR = 0      | ( 0                       * DMA_SxFCR_DMDIS )     // direct mode      | (DMA_SxFCR_FTH__FULL      * DMA_SxFCR_FTH_0 )     // [irrelevant - keep it full]      | ( 0                       * DMA_SxFCR_FEIE  )     // no interrupt    ;    DMAStream->CR = 0      | (_Channel_                * DMA_SxCR_CHSEL_0   )  // channel select      | (DMA_SxCR_xBURST_INCR1    * DMA_SxCR_MBURST_0  )  // memory burst (only in FIFO mode)      | (DMA_SxCR_xBURST_INCR1    * DMA_SxCR_PBURST_0  )  // peripheral burst (only in FIFO mode)      | (0                        * DMA_SxCR_ACK       )  // "reserved" (says manual)      | (0                        * DMA_SxCR_CT        )  // current target (only in double-buffer mode)      | (0                        * DMA_SxCR_DBM       )  // double-buffer mode      | (DMA_SxCR_PL_PRIORITY_VERY_HIGH * DMA_SxCR_PL_0      )  // priority level      | (0                        * DMA_SxCR_PINCOS    )  // peripheral increment offset size (only if peripheral address increments, FIFO mode and PBURST is 0)      | (DMA_SxCR_xSIZE_WORD      * DMA_SxCR_MSIZE_0   )  // memory data size; in direct mode forced to the same value as PSIZE      | (DMA_SxCR_xSIZE_WORD      * DMA_SxCR_PSIZE_0   )  // peripheral data size      | (1                        * DMA_SxCR_MINC      )  // memory address increments      | (1                        * DMA_SxCR_PINC      )  // peripheral address increments      | (0                        * DMA_SxCR_CIRC      )  // circular mode (forced to 1 if double-buffer mode, forced to 0 if flow control is peripheral)      | (DMA_SxCR_DIR_M2P         * DMA_SxCR_DIR_0     )  // data transfer direction      | (0                        * DMA_SxCR_PFCTRL    )  // peripheral is the flow controller (i.e. who determines end of transfer) - only for SDIO      | (0                        * DMA_SxCR_TCIE      )  // transfer complete interrupt enable      | (0                        * DMA_SxCR_HTIE      )  // half transfer interrupt enable      | (0                        * DMA_SxCR_TEIE      )  // transfer error interrupt enable      | (0                        * DMA_SxCR_DMEIE     )  // direct mode error interrupt enable      | (1                        * DMA_SxCR_EN        )  // stream enable        ;    ;  RCC->APBxENR |= RCC_APBxENR_TIMzEN;  TIMz->PSC = 0;  // clk is 16MHz, no prescaler  TIMz->ARR = 100;   // -> the whole 10-beat DMA transfer takes cca 1000 clk  TIMz->DIER = TIM_DIER_UDE;   /* Update DMA enable */  TIMz->CR1 = TIM_CR1_CEN;   /* Counter enable */  while (!(DMAx->yISR & DMA_yISR_TCIFz));    // wait until DMA transfer finishes  __NOP();  // place "finished" breakpoint here  while(1) {  }}