http://www.efton.sk/STM32/bt.c
// 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 <stdint.h> #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 10 volatile uint32_t src[BUFSIZE] = {, , , , , , , , , };
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 =
| ( * DMA_SxFCR_DMDIS ) // direct mode
| (DMA_SxFCR_FTH__FULL * DMA_SxFCR_FTH_0 ) // [irrelevant - keep it full]
| ( * DMA_SxFCR_FEIE ) // no interrupt
; DMAStream->CR =
| (_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)
| ( * DMA_SxCR_ACK ) // "reserved" (says manual)
| ( * DMA_SxCR_CT ) // current target (only in double-buffer mode)
| ( * DMA_SxCR_DBM ) // double-buffer mode
| (DMA_SxCR_PL_PRIORITY_VERY_HIGH * DMA_SxCR_PL_0 ) // priority level
| ( * 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
| ( * DMA_SxCR_MINC ) // memory address increments
| ( * DMA_SxCR_PINC ) // peripheral address increments
| ( * 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
| ( * DMA_SxCR_PFCTRL ) // peripheral is the flow controller (i.e. who determines end of transfer) - only for SDIO
| ( * DMA_SxCR_TCIE ) // transfer complete interrupt enable
| ( * DMA_SxCR_HTIE ) // half transfer interrupt enable
| ( * DMA_SxCR_TEIE ) // transfer error interrupt enable
| ( * DMA_SxCR_DMEIE ) // direct mode error interrupt enable
| ( * DMA_SxCR_EN ) // stream enable ;
; RCC->APBxENR |= RCC_APBxENR_TIMzEN; TIMz->PSC = ; // clk is 16MHz, no prescaler
TIMz->ARR = ; // -> 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() { } }