stm32h7 dma i2c

### STM32H7 DMA with I2C Communication Example and Configuration Guide For configuring the Direct Memory Access (DMA) to work alongside Inter-integrated Circuit (I2C) on an STM32H7 series microcontroller, it involves setting up both peripherals correctly within a project using either HAL libraries or standard peripheral library functions provided by ST Microelectronics. The setup process includes enabling clocks for I2C and DMA controllers along with configuring GPIO pins as alternate function for SCL and SDA lines of I2C bus. For initializing DMA channels associated specifically with chosen I2C interface, parameters such as direction, buffer address, number of data items need specification[^1]. A simplified code snippet demonstrating initialization can be seen below: ```c // Enable Clocks __HAL_RCC_DMA1_CLK_ENABLE(); __HAL_RCC_I2C1_CLK_ENABLE(); // Configure GPIO Pins GPIO_InitTypeDef GPIO_InitStruct = {0}; __HAL_RCC_GPIOB_CLK_ENABLE(); // Assuming PB6(SCL),PB7(SDA) /*Configure GPIO pin : PB6 */ GPIO_InitStruct.Pin = GPIO_PIN_6; GPIO_InitStruct.Mode = GPIO_MODE_AF_OD; // Open Drain Mode GPIO_InitStruct.Pull = GPIO_NOPULL; GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH; GPIO_InitStruct.Alternate = GPIO_AF4_I2C1; HAL_GPIO_Init(GPIOB, &GPIO_InitStruct); /*Configure GPIO pin : PB7*/ GPIO_InitStruct.Pin = GPIO_PIN_7; HAL_GPIO_Init(GPIOB, &GPIO_InitStruct); ``` To initialize DMA channel linked with I2C transmission/reception requires defining structures like `DMA_HandleTypeDef` where attributes including memory-to-peripheral transfer mode (`hdma_i2c_tx.Init.Direction`) are set according to application requirements before calling respective init methods from HAL API: ```c static void MX_DMA_Init(void){ /* Init DMAs low Level Parameters */ __HAL_RCC_DMA1_CLK_ENABLE(); hdma_i2c1_rx.Instance = DMA1_Stream0; hdma_i2c1_rx.Init.Channel = DMA_CHANNEL_1; hdma_i2c1_rx.Init.Direction = DMA_PERIPH_TO_MEMORY; hdma_i2c1_rx.Init.PeriphInc = DMA_PINC_DISABLE; hdma_i2c1_rx.Init.MemInc = DMA_MINC_ENABLE; hdma_i2c1_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE; hdma_i2c1_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE; hdma_i2c1_rx.Init.Mode = DMA_NORMAL; hdma_i2c1_rx.Init.Priority = DMA_PRIORITY_LOW; hal_dma_init(&hdma_i2c1_rx); __HAL_LINKDMA(hi2c1, hdmarx, hdma_i2c1_rx); // Similar steps apply for TX DMA Stream/Channel... } ``` Afterwards, when performing actual transfers via I2C utilizing DMA, one would typically call APIs similar to those shown hereunder which handle starting transactions asynchronously while leveraging underlying hardware resources efficiently through direct memory access mechanisms without CPU intervention during bulk operations: ```c uint8_t DataToSend[] = "HelloWorld"; HAL_I2C_Master_Transmit_DMA(&hi2c1, AddressOfSlaveDevice<<1 , DataToSend,strlen((char*)DataToSend)); ```