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215 lines
13 KiB
Plaintext
Executable File
215 lines
13 KiB
Plaintext
Executable File
/**
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@page CDC_Standalone USB Device Communication (CDC) application
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@verbatim
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******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
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* @file USB_Device/CDC_Standalone/readme.txt
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* @author MCD Application Team
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* @brief Description of the USB Device CDC application.
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******************************************************************************
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted, provided that the following conditions are met:
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*
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* 1. Redistribution of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. Neither the name of STMicroelectronics nor the names of other
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* contributors to this software may be used to endorse or promote products
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* derived from this software without specific written permission.
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* 4. This software, including modifications and/or derivative works of this
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* software, must execute solely and exclusively on microcontroller or
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* microprocessor devices manufactured by or for STMicroelectronics.
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* 5. Redistribution and use of this software other than as permitted under
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* this license is void and will automatically terminate your rights under
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* this license.
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*
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* THIS SOFTWARE IS PROVIDED BY STMICROELECTRONICS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS, IMPLIED OR STATUTORY WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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* PARTICULAR PURPOSE AND NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY
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* RIGHTS ARE DISCLAIMED TO THE FULLEST EXTENT PERMITTED BY LAW. IN NO EVENT
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* SHALL STMICROELECTRONICS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
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* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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******************************************************************************
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@endverbatim
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@par Application Description
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This application is a part of the USB Device Library package using STM32Cube firmware. It describes how to
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use USB device application based on the Device Communication Class (CDC) following the PSTN subprotocol
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in the STM32H743xx devices using the OTG-USB and UART peripherals.
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This is a typical application on how to use the STM32H743xx USB OTG Device peripheral where the STM32 MCU
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behaves as a USB-to-RS232 bridge following the Virtual COM Port (VCP) implementation.
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- On one side, the STM32 exchanges data with a PC host through USB interface in Device mode.
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- On the other side, the STM32 exchanges data with other devices (same host, other host,
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other devices<65> through the UART interface (RS232).
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At the beginning of the main program the HAL_Init() function is called to reset
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all the peripherals, initialize the Flash interface and the systick.
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The SystemClock_Config() function is used to configure the system clock for STM32H743xx Devices :
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The CPU at 400MHz
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The HCLK for D1 Domain AXI and AHB3 peripherals , D2 Domain AHB1/AHB2 peripherals and D3 Domain AHB4 peripherals at 200MHz.
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The APB clock dividers for D1 Domain APB3 peripherals, D2 Domain APB1 and APB2 peripherals and D3 Domain APB4 peripherals to run at 100MHz.
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The Full Speed (FS) USB module uses
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internally a 48-MHz clock which is coming from a specific output of two PLLs: main PLL1 or PLL3.
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In the High Speed (HS) mode the USB clock (60 MHz) is driven by the ULPI.
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The 48 MHz clock for the USB FS is derived from the PLL3 clock (clocked by the HSE)
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When the VCP application is started, the STM32 MCU is enumerated as serial communication port and is
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configured in the same way (baudrate, data format, parity, stop bit) as it would configure a standard
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COM port. The 7-bit data length with no parity control is NOT supported.
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During enumeration phase, three communication pipes "endpoints" are declared in the CDC class
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implementation (PSTN sub-class):
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- 1 x Bulk IN endpoint for receiving data from STM32 device to PC host:
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When data are received over UART they are saved in the buffer "UserTxBuffer". Periodically, in a
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timer callback the state of the buffer "UserTxBuffer" is checked. If there are available data, they
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are transmitted in response to IN token otherwise it is NAKed.
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The polling period depends on "CDC_POLLING_INTERVAL" value.
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- 1 x Bulk OUT endpoint for transmitting data from PC host to STM32 device:
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When data are received through this endpoint they are saved in the buffer "UserRxBuffer" then they
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are transmitted over UART using interrupt mode and in meanwhile the OUT endpoint is NAKed.
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Once the transmission is over, the OUT endpoint is prepared to receive next packet in
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HAL_UART_TxCpltCallback().
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- 1 x Interrupt IN endpoint for setting and getting serial-port parameters:
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When control setup is received, the corresponding request is executed in CDC_Itf_Control().
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In this application, two requests are implemented:
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- Set line: Set the bit rate, number of Stop bits, parity, and number of data bits
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- Get line: Get the bit rate, number of Stop bits, parity, and number of data bits
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The other requests (send break, control line state) are not implemented.
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@note Receiving data over UART is handled by interrupt while transmitting is handled by DMA allowing
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hence the application to receive data at the same time it is transmitting another data (full-
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duplex feature).
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The support of the VCP interface is managed through the ST Virtual COM Port driver available for
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download from www.st.com.
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@note The user has to check the list of the COM ports in Device Manager to find out the number of the
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COM ports that have been assigned (by OS) to the VCP interface.
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This application uses UART as a communication interface. The UART instance and associated resources
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(GPIO, NVIC) can be tailored in "usbd_cdc_interface.h" header file according to your hardware
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configuration. Moreover, this application can be customized to communicate with interfaces other than UART.
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For that purpose a template CDC interface is provided in:
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Middlewares/ST/STM32_USB_Device_Library/Class/CDC/Src directory.
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In High Speed (HS) mode, enabling USB-DMA will result in data being sent only by multiple of 4 packet
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sizes. This is due to the fact that USB DMA does not allow sending data from non word-aligned addresses.
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For this specific application, it is advised to not enable the DMA capability unless required.
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To run this application, the user can use one of the following configurations:
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- Configuration 1:
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Connect USB cable to host and UART (RS232) to a different host (PC or other device) or to same host.
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In this case, you can open two hyperterminals to send/receive data to/from host to/from device.
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- Configuration 2:
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Connect USB cable to Host and connect UART TX pin to UART RX pin on the STM32H743I-EVAL board
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(Loopback mode). In this case, you can open one terminal (relative to USB com port or UART com port)
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and all data sent from this terminal will be received by the same terminal in loopback mode.
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This mode is useful for test and performance measurements.
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@note If using this example in loopback mode (ie. USART Tx IO connected to USART Rx IO on STM32 side)
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and with baudrates higher than 9600, there might be communication errors.
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@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
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based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
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a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
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than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
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@note The application needs to ensure that the SysTick time base is always set to 1 millisecond
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to have correct HAL operation.
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For more details about the STM32Cube USB Device library, please refer to UM1734
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"STM32Cube USB Device library".
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@par USB Library Configuration
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To select the appropriate USB Core to work with, user must add the following macro defines within the
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compiler preprocessor (already done in the preconfigured projects provided with this application):
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- "USE_USB_HS" when using USB High Speed (HS) Core
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- "USE_USB_FS" when using USB Full Speed (FS) Core
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@Note If the application is using the DTCM/ITCM memories (@0x20000000/ 0x0000000: not cacheable and only accessible
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by the Cortex M7 and the 燤DMA), no need for cache maintenance when the Cortex M7 and the MDMA access these RAMs.
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牋牋<EFBFBD>If the application needs to use DMA(or other masters) based access or requires more RAM, then 爐he user has to:
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牋牋牋牋牋<EFBFBD><EFBFBD>- Use a non TCM SRAM. (example : D1 AXI-SRAM @ 0x24000000)
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牋牋牋牋牋<EFBFBD><EFBFBD>- Add a cache maintenance mechanism to ensure the cache coherence between CPU and other masters(DMAs,DMA2D,LTDC,MDMA).
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牋牋牋<EFBFBD> - The addresses and the size of cacheable buffers (shared between CPU and other masters)
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must be properly燿efined to be aligned to L1-CACHE line size (32 bytes).
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<EFBFBD>@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
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牋牋<EFBFBD>It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
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牋牋牋牋牋<EFBFBD><EFBFBD>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
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牋牋牋牋牋<EFBFBD><EFBFBD>Even though the user must manage the cache coherence for read accesses.
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牋牋牋牋牋牋牋Please refer to the AN4838 揗anaging memory protection unit (MPU) in STM32 MCUs<55>牋牋牋牋牋牋牋Please refer to the AN4839 揕evel 1 cache on STM32F7 Series<65>
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@par Directory contents
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- USB_Device/CDC_Standalone/Src/main.c Main program
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- USB_Device/CDC_Standalone/Src/system_stm32h7xx.c STM32H743xx system clock configuration file
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- USB_Device/CDC_Standalone/Src/stm32h7xx_it.c Interrupt handlers
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- USB_Device/CDC_Standalone/Src/stm32h7xx_hal_msp.c HAL MSP module
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- USB_Device/CDC_Standalone/Src/usbd_cdc_interface.c USBD CDC interface
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- USB_Device/CDC_Standalone/Src/usbd_conf.c General low level driver configuration
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- USB_Device/CDC_Standalone/Src/usbd_desc.c USB device CDC descriptor
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- USB_Device/CDC_Standalone/Inc/main.h Main program header file
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- USB_Device/CDC_Standalone/Inc/stm32h7xx_it.h Interrupt handlers header file
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- USB_Device/CDC_Standalone/Inc/stm32h7xx_hal_conf.h HAL configuration file
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- USB_Device/CDC_Standalone/Inc/usbd_conf.h USB device driver Configuration file
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- USB_Device/CDC_Standalone/Inc/usbd_desc.h USB device MSC descriptor header file
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- USB_Device/CDC_Standalone/Inc/usbd_cdc_interface.h USBD CDC interface header file
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@par Hardware and Software environment
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- This application runs on STM32H743xx devices.
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- This application has been tested with STMicroelectronics STM32H743I-EVAL RevB
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evaluation boards and can be easily tailored to any other supported device
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and development board.
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- STM32H743I-EVAL RevB Set-up
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- Connect the STM32H743I-EVAL board to the PC through 'USB micro A-Male
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to A-Male' cable to the connector:
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- CN14 : to use USB High Speed (HS)
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- CN18: to use USB Full Speed (FS)
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Please ensure that jumper JP2 is not fitted.
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- Connect the STM32H743I-EVAL board to the PC (or to another evaluation board) through RS232 (USART)
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serial cable CN2 connector. Please ensure that jumper JP7 and JP8 are fitted in RS232 TX/RX position.
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- For loopback mode test: remove RS232 cable on CN2 and connect directly USART TX and RX pins:
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PB14 and PB15 (with a cable or a jumper)
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@par How to use it ?
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In order to make the program work, you must do the following :
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- In the workspace toolbar select the project configuration:
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- STM32H743I-EVAL_USBH-HS: to configure the project for STM32H7xx devices using USB OTG HS peripheral
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- STM32H743I-EVAL_USBH-FS: to configure the project for STM32H7xx devices using USB OTG FS peripheral
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- Run the application
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- Install the USB virtual COM port driver
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- Find out the number of the COM port assigned to the STM32 CDC device
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- Open a serial terminal application and start the communication
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* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
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*/
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