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

STM32F0xx Standard Peripherals Library

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SPI Communication Boards Data Exchange using DMA example 
  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    SPI/SPI_TwoBoards/DataExchangeDMA/readme.txt  
  * @author  MCD Application Team
  * @version V1.4.0
  * @date    24-July-2014
  * @brief   Description of the SPI 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 SPI communications using DMA and though using SPI 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 SPI lines and GND. In the STM32 master board (Board A), connect the timer output capture compare channel into NSS line. In the firmware example uncomment the dedicated line in the main.h file to use the SPI peripheral as STM32 Master device or as STM32 Slave.

*------------------------------------------------------------------------------*
|                BOARD A                                BOARD B                |
|         ____________________                   ____________________          |
|        |                    |                 |                    |         |
|        |                    |                 |                    |         | 
|        |     __________ ____|_______SCK_______|____ __________     |         |
|        |    |SPI Master|____|_______MOSI______|____|SPI Slave |    |         |
|        |    |  Device  |____|_______MISO______|____|  Device  |    |         |
|        |    |__________|____|_______NSS_______|____|__________|    |         |
|        |                    |   |             |                    |         |
|        |  O LD1  TIM_CHx O__|___|             |  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 short wires and a common Ground.
  • Software Description

In master board, SPI peripheral is configured as Master full duplex with DMA and NSS hardware mode. The TIM2 is configured to generate 4KHz PWM signal with 50% duty cycle on TIM2_CH2 pin (PA.01), this signal is used as DMA trigger and as NSS signal input to latch the SPI data transfers. Whereas in Slave board, SPI peripheral is configured as Slave Full duplex with DMA and NSS hardware mode.

At each joystick buttons press:

  • The Master sends the specific command to the Slave using the TIM2_CH2 DMA request (DMA1_Channel3)(the command contains the transaction code (CMD_RIGHT, CMD_LEFT, CMD_UP, CMD_DOWN or CMD_SEL) and receives the ACK command from the Slave using SPI_Rx DMA request(DMA1_Channel2)
  • The Slave receives the command using SPI_Rx DMA request(DMA1_Channel2) and sends the ACK command using the SPI_Tx DMA request (DMA1_Channel3).
  • The Master sends the defined NumberOfByte from TxBuffer using the TIM2_CH2 DMA request (DMA1_Channel3) to the Slave and receives NumberOfByte from the Slave using SPI_Rx DMA request(DMA1_Channel2) into Rxbuffer.
  • The Slave sends the defined NumberOfByte from Txbuffer using the SPI_Tx DMA request (DMA1_Channel3) to the Master and receives NumberOfByte from the Master using SPI_Rx DMA request(DMA1_Channel2) into Rxbuffer.
  • The Master compares the NumberOfByte received data with the defined ones into TxBuffer and check the ACK command, received data correctness is signaled by LD lightening and though as follow:
    • Joystick JOY_RIGHT and data correctly received ==> LD2 and LD3 ON and LD4 OFF
    • Joystick JOY_LEFT and data correctly received ==> LD4 ON, LD2 and LD3 are OFF
    • Joystick JOY_UP and data correctly received ==> LD2 ON, LD3 and LD4 are OFF
    • Joystick JOY_DOWN and data correctly received ==> LD3 ON, LD2 and LD4 are OFF
    • Joystick JOY_SEL and data correctly received ==> LD2, LD3 and LD4 leds ON
  • The Slave compares the NumberOfByte received data with the defined ones into TxBuffer and check the received command,Received data correctness is signaled by LED lightening and though as follow:
    • Received command CMD_RIGHT and data correctly received ==> LD2 and LD3 ON and LD4 OFF
    • Received command CMD_LEFT and data correctly received ==> LD2 ON, LD3 and LD4 are OFF
    • Received command CMD_UP and data correctly received ==> LD2 ON, LD3 and LD4 are OFF
    • Received command CMD_DOWN and data correctly received ==> LD3 ON, LD2 and LD4 are OFF
    • Received command CMD_SEL and data correctly received ==> LD2, LD3 and LD4 leds ON

In both boards, the SPI is configured to use the slave hardware management to manage the NSS pin.

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 SPI 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
    • Use LED1, LED2, LED3 and LED4 connected respectively PC.10, PC.11, PC.12 and PD.02 pins for each eval boards.
    • Use The Joystick push buttons
      • DOWN[PC.07]
      • UP[PC.06]
      • LEFT[PC.09]
      • RIGHT[PC.08]
      • SEL[PA.00]

Connect SPI1 SCK pin (PA.05) to SPI SCK pin

  • Connect SPI1 MISO pin (PB.04) to SPI MISO pin
  • Connect SPI1 MOSI pin (PA.07) to SPI MOSI pin
  • Connect SPI1 NSS pin (PA.15) to SPI NSS pin
  • Connect TIM2_CH2 pin (PA.01) to SPI1 NSS pin (PA.15) (On master board only to trigger the DMA transfers)
  • Connect GND pins of two boards.
  • STM32072B-EVAL Set-up
    • Use LED1, LED2, LED3 and LED4 connected respectively PD.08, PD.09, PD.10 and PD.11 pins for each eval boards.
    • Use The Joystick push buttons
      • DOWN[PF.10]
      • UP[PF.09]
      • LEFT[PE.02]
      • RIGHT[PE.03]
      • SEL[PA.00]
    • Connect SPI1 SCK pin (PB.03) to SPI SCK pin
    • Connect SPI1 MISO pin (PE.15) to SPI MISO pin
    • Connect SPI1 MOSI pin (PE.14) to SPI MOSI pin
    • Connect SPI1 NSS pin (PA.15) to SPI NSS pin (PA.15)
    • Connect TIM2_CH2 pin (PA.01) to SPI1 NSS pin (PA.15) (On master board only to trigger the DMA transfers)
    • Connect GND pins of two boards.
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

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