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15. DMA：USART

DMA：USART

DMA：USART1、software-hardware2、Brief principle2.1、Hardware schematic diagram2.2、Physical connection diagram3.3、Principle of control3、Engineering configuration3.1、Notes3.2、Pin configuration4、Main Function4.1、User function4.2、LL library function analysis5、Experimental phenomenon

This tutorial demonstrates Serial (USART1) communication via DMA

1、software-hardware

STM32F103CubeIDE
STM32 robot expansion board
USART1, DMA: chip internal peripheral
Type-C cable or ST-Link
Download or simulate the program of the development board

2、Brief principle

2.1、Hardware schematic diagram

The schematic only shows the serial interface used in the tutorial (USART1)

2.2、Physical connection diagram

3.3、Principle of control

USART1

The knowledge related to serial port will not be introduced, you can see before [Chapter 3:3.4 Serial communication]

DMA（Direct Memory Access）

STM32F103ZET6 has a total of two DMA controllers, DMA1 has 7 channels, DMA2 has 5 channels;

It is used for high-speed data transfer between peripheral equipment and memory and between memory and memory.

DMA features

The initialization and start of DMA are completed by the CPU, and the transfer process is executed by the DMA controller without the participation of the CPU, so that the CPU resources are saved to do other operations

DMA1 requests per channel

DMA2 requests per channel

DMA1 channels 4 and 5 are used in this tutorial

3、Engineering configuration

Project Configuration: Prompts for configuration options in the STM32CubeIDE project configuration process

3.1、Notes

Omitted project configuration: New project, chip selection, project configuration, SYS for pin configuration, RCC configuration, clock configuration, and project configuration content

The project configuration part, which is not omitted, is the key point to configure in this tutorial.


Please refer to [2. Development environment construction and use: STM32CubeIDE installation and use] to understand how to configure the omitted parts of the project.

3.2、Pin configuration

Configure the specified pin function

You can directly select the corresponding pin number in the pin view, and the corresponding option will appear when the mouse is left clicked

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USART1

NVIC
NVIC can modify interrupt priority

Advanced Settings

Generating code

4、Main Function

This section mainly introduces the functional code written by users. Detailed code can be opened by yourself in the project file we provide, and enter the Bsp folder to view the source code. .

4.1、User function

function：USART1_DataByte

Function prototypes	void USART1_DataByte(uint8_t data_byte)
Functional Description	Sending a single byte
Input parameters	data_byte：Data to be sent
Return value	None
Tips	Define the DMA_USART macro to switch between DMA transfer and USART directly

function：USART1_DataString

Function prototypes	void USART1_DataString(uint8_t *data_str, uint16_t datasize)
Functional Description	Sending strings
Input parameters1	data_str：The first address to send data to
Input parameters2	datasize：Data size
Return value	None
Tips	Define the DMA_USART macro to switch between DMA transfer and USART directly

4.2、LL library function analysis

LL library functions that have been covered in the previous tutorial will not be covered in the tutorial


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If you want to find the HAL library and LL library function analysis involved in the entire tutorial, you can view the documents in the folder [8. STM32 Manual: STM32F1_HAL Library and LL Library_User Manual]

function：LL_DMA_SetDataTransferDirection

Function prototypes	void LL_DMA_SetDataTransferDirection(DMA_TypeDef *DMAx, uint32_t Channel, uint32_t Direction)
Functional Description	Set the direction of data transmission
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	Direction：Direction of data transmission
Return value	None

function：LL_DMA_SetChannelPriorityLevel

Function prototypes	void LL_DMA_SetChannelPriorityLevel(DMA_TypeDef *DMAx, uint32_t Channel, uint32_t Priority)
Functional Description	Set the priority of the DMA channel
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	Priority：priority
Return value	None

function：LL_DMA_SetMode

Function prototypes	void LL_DMA_SetMode(DMA_TypeDef *DMAx, uint32_t Channel, uint32_t Mode)
Functional Description	Set DMA working mode
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	Mode：Mode of work
Return value	None

function：LL_DMA_SetPeriphIncMode

Function prototypes	void LL_DMA_SetPeriphIncMode (DMA_TypeDef *DMAx, uint32_t Channel, uint32_t PeriphOrM2MSrcIncMode)
Functional Description	Set DMA peripheral delta mode
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	PeriphOrM2MSrcIncMode：Incremental mode selection
Return value	None

function：LL_DMA_SetMemoryIncMode

Function prototypes	void LL_DMA_SetMemoryIncMode (DMA_TypeDef *DMAx, uint32_t Channel, uint32_t MemoryOrM2MDstIncMode)
Functional Description	Set DMA memory increment mode
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	MemoryOrM2MDstIncMode：Incremental mode selection
Return value	None

function：LL_DMA_SetPeriphSize

Function prototypes	void LL_DMA_SetPeriphSize(DMA_TypeDef *DMAx, uint32_t Channel, uint32_t PeriphOrM2MSrcDataSize)
Functional Description	Set the peripheral data size
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	PeriphOrM2MSrcDataSize：Data size
Return value	None

function：LL_DMA_SetMemorySize

Function prototypes	void LL_DMA_SetMemorySize (DMA_TypeDef *DMAx, uint32_t Channel, uint32_t MemoryOrM2MDstDataSize)
Functional Description	Set the memory data size
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	MemoryOrM2MDstDataSize：Data size
Return value	None

function：LL_DMA_SetMemoryAddress

Function prototypes	void LL_DMA_SetMemoryAddress(DMA_TypeDef *DMAx, uint32_t Channel, uint32_t MemoryAddress)
Functional Description	Set the DMA memory address
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	MemoryAddress：Memory address
Return value	None

function：LL_DMA_SetPeriphAddress

Function prototypes	void LL_DMA_SetPeriphAddress(DMA_TypeDef *DMAx, uint32_t Channel, uint32_t PeriphAddress)
Functional Description	Set the DMA peripheral address
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	PeriphAddress：Peripheral device address
Return value	None

function：LL_DMA_SetDataLength

Function prototypes	void LL_DMA_SetDataLength(DMA_TypeDef *DMAx, uint32_t Channel, uint32_t NbData)
Functional Description	Set the length of DMA transfer data
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Input parameters3	NbData：Data length
Return value	None

function：LL_DMA_EnableChannel

Function prototypes	void LL_DMA_EnableChannel(DMA_TypeDef *DMAx, uint32_t Channel)
Functional Description	Enable DMA channels
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Return value	None

function：LL_DMA_DisableChannel

Function prototypes	void LL_DMA_DisableChannel(DMA_TypeDef *DMAx, uint32_t Channel)
Functional Description	Closing the DMA channel
Input parameters1	DMAx：DMA handle address
Input parameters2	Channel：DMA channel number in the range 0 to 7
Return value	None

function：LL_USART_EnableDMAReq_RX

Function prototypes	void LL_USART_EnableDMAReq_RX(USART_TypeDef *USARTx)
Functional Description	Enable DMA serial port reception
Input parameters	USARTx：USART handle address
Return value	None

function：LL_USART_EnableDMAReq_TX

Function prototypes	void LL_USART_EnableDMAReq_TX(USART_TypeDef *USARTx)
Functional Description	Enable DMA serial port sending
Input parameters	USARTx：USART handle address
Return value	None

5、Experimental phenomenon

After downloading the program successfully, press the RESET button of the development board to open the serial debugging assistant to observe the phenomenon


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For program download, please refer to [2. Development environment construction and use: program download and simulation]

phenomenon：

Press RESET button, serial debugging assistant will print USRT+DMA Class! Character;

Then through the serial port debug assistant to send what information will print the corresponding information

On-chip Flash (Flash)

DMA：SPI