STM32F0xx Standard Peripherals Firmware Library: USART Communication Boards Data Exchange using DMA example

STM32F0xx Standard Peripherals Library

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USART Communication Boards Data Exchange using DMA example 
  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    USART/USART_TwoBoards/DataExchangeDMA/readme.txt 
  * @author  MCD Application Team
  * @version V1.4.0
  * @date    24-July-2014
  * @brief   Description of the USART Communication Boards Data Exchange using 
  *          DMA example.
  ******************************************************************************
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
Example Description

This example provides a small application in which joystick buttons are used to trigger USART communications using DMA and though using USART firmware library.

  • Hardware Description

To use this example, you need to load it on two STM32 boards (let's call them Board A and Board B) then connect these two boards through USART lines and GND.

*------------------------------------------------------------------------------*
|                BOARD A                                BOARD B                |
|         ____________________                   ____________________          |
|        |                    |                 |                    |         |
|        |                    |                 |                    |         | 
|        |     __________     |                 |     __________     |         |
|        |    |   USART  |____|TX_____________RX|____|   USART  |    |         |
|        |    |  Device1 |____|RX_____________TX|____|  Device2 |    |         |
|        |    |__________|    |                 |    |__________|    |         |
|        |                    |                 |                    |         |
|        |  O LD1             |                 |  O LD1             |         |
|        |  O LD2    Joystick |                 |  O LD2    Joystick |         |
|        |  O LD3        _    |                 |  O LD3        _    |         |
|        |  O LD4       |_|   |                 |  O LD4       |_|   |         |
|        |                    |                 |                    |         |
|        |             GND O--|-----------------|--O GND             |         |
|        |____________________|                 |____________________|         |
|                                                                              |
|                                                                              |
*------------------------------------------------------------------------------*
Note:
  • The connection between the pins should use a common Ground.
  • Software Description

On Board A, at each joystick buttons press:

  • The USART Board A sends the specific command to the USART Board B (the command contains the transaction code (CMD_RIGHT, CMD_LEFT, CMD_UP, CMD_DOWN or CMD_SEL) followed by the number of data to be transmitted (CMD_RIGHT_SIZE, CMD_LEFT_SIZE, CMD_UP_SIZE, CMD_DOWN_SIZE or CMD_SEL_SIZE)
  • The USART Board B receives the command and sends the CMD_ACK command to the USART board A
  • The USART Board A receives the CMD_ACK command and sends the number of bytes from TxBuffer to the USART Board B.
  • The USART Board B compares the number of bytes received with the defined ones into his TxBuffer.

Received data correctness is signaled by LED lightening and though as follow:

  • Joystick RIGHT and data correctly received ==> LD2, LD3 ON and LD4 OFF
  • Joystick LEFT and data correctly received ==> LD4 ON, LD2 and LD3 are OFF
  • Joystick UP and data correctly received ==> LD2 ON, LD3 and LD4 are OFF
  • Joystick DOWN and data correctly received ==> LD3 ON, LD2 and LD4 are OFF
  • Joystick SEL and data correctly received ==> LD2, LD3 and LD4 are ON

The steps described above can be also initiated and ensured by Board B.

In both boards(Board A or Board B), the data transfers is managed using the USART Tx/Rx channels DMA requests.

The SysTick is configured to generate interrupt each 10ms. A dedicated counter inside the SysTick ISR is used to toggle the LD1 each 100ms indicating that the firmware is running.

A defined communication timeout is insuring that the application will not remain stuck if the USART communication is corrupted. You can adjust this timeout through the USER_TIMEOUT define inside main.h file depending on CPU frequency and application conditions (interrupts routines, number of data to transfer, baudrate, CPU frequency...).

These operations can be repeated infinitely.

Directory contents
Note:
The "system_stm32f0xx.c" is generated by an automatic clock configuration tool and can be easily customized to meet user application requirements. To select different clock setup, use the "STM32F0xx_Clock_Configuration_VX.Y.Z.xls" provided with the AN4055 package available on ST Microcontrollers
Hardware and Software environment
  • This example runs on STM32F0xx devices.
  • This example has been tested with STMicroelectronics STM320518-EVAL and STM32072B-EVAL including respectively STM32F051R8T6 and STM32F072VBT6 devices and can be easily tailored to any other supported device and development board
  • STM320518-EVAL Set-up
    • Connect USART1 TX pin (PA.09) to USARTx RX pin
    • Connect USART1 RX pin (PA.10) to USARTx TX pin
    • Connect GND pins of two boards
    • JP3 should be in 5-6 position
  • STM32072B-EVAL Set-up
    • Connect USART2 TX pin (PD.05) to USARTx RX pin
    • Connect USART2 RX pin (PD.06) to USARTx TX pin
    • Connect GND pins of two boards
    • JP17 should be in 5-6 position
How to use it ?

In order to make the program work, you must do the following :

  • Copy all source files from this example folder to the template folder under Project
  • Open your preferred toolchain
  • If the used device is STM32F051R8T6 choose STM32F051 project
    • Add the following files to the project source list
      • Utilities\STM32_EVAL\STM320518_EVAL\stm320518_eval.c
  • If the used device is STM32F072VBT6 choose STM32F072 project
    • Add the following files to the project source list
      • Utilities\STM32_EVAL\STM32072B_EVAL\stm32072b_eval.c
  • Rebuild all files and load your image into target memory
  • Run the example

© COPYRIGHT STMicroelectronics

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