How to use a DMA to transfer a word data buffer from Flash memory to embedded SRAM through the STM32C0xx DMA HAL and LL API. The LL API is used for performance improvement.
At the beginning of the main program the HAL_Init() function is called to reset all the peripherals, initialize the Flash interface and the systick. Then the SystemClock_Config() function is used to configure the system clock (SYSCLK) to run at 48 MHz.
DMA1_Channel1 is configured to transfer the contents of a 32-word data buffer stored in Flash memory to the reception buffer declared in RAM.
The start of transfer is triggered by LL API. DMA1_Channel1 memory-to-memory transfer is enabled. Source and destination addresses incrementing is also enabled. The transfer is started by setting the channel enable bit for DMA1_Channel1. At the end of the transfer a Transfer Complete interrupt is generated since it is enabled and the callback function (customized by user) is called.
Board’s LEDs can be used to monitor the transfer status:
It is possible to select a different channel for the DMA transfer example by modifying defines values in the file main.h.
Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds) based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower) than the peripheral interrupt. Otherwise the caller ISR process will be blocked. To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
This example need to ensure that the SysTick time base is always set to 1 millisecond to have correct HAL operation.
System, DMA, Data Transfer, Memory to memory, Flash, SRAM
This example runs on STM32C031C6Tx Devices.
This example has been tested with STMicroelectronics NUCLEO-C031C6 board and can be easily tailored to any other supported device and development board.
In order to make the program work, you must do the following :