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Nx_HTTP_SSE_wifi application description

This application provides an example of Azure RTOS NetX/NetXDuo stack usage.

It demonstrates a HTTP server application using the WiFi connectivity on Cypress module. The IP address of the target board to connect to is displayed on the UART. The end-user can connect to it through an HTTP client browser.

Expected success behavior

This HTTP server response one html page:

  • the page is updated each time events are sent by the server, meaning information about the Live thread list.

Error behaviors

An error message is displayed on the UART in case there are too many clients trying to connect. Removing a web page for a client enables a new client to be requested.

Assumptions if any

None

ThreadX usage hints

  • ThreadX uses the Systick as time base, thus it is mandatory that the HAL uses a separate time base through the TIM IPs.

  • ThreadX is configured with 1000 ticks/sec, this should be taken into account when using delays or timeouts at application. It is always possible to reconfigure it in the tx_user.h, the TX_TIMER_TICKS_PER_SECOND define, but this should be reflected in tx_initialize_low_level.S file too.

  • ThreadX is disabling all interrupts during kernel start-up to avoid any unexpected behavior, therefore all system related calls (HAL, BSP) should be done either at the beginning of the application or inside the thread entry functions.

  • ThreadX offers the tx_application_define() function, that is automatically called by the tx_kernel_enter() API. It is highly recommended to use it to create all applications ThreadX related resources (threads, semaphores, memory pools...) but it should not in any way contain a system API call (HAL or BSP).

  • Using dynamic memory allocation requires to apply some changes to the linker file. ThreadX needs to pass a pointer to the first free memory location in RAM to the tx_application_define() function, using the first_unused_memory argument. This requires changes in the linker files to expose this memory location.

    • For EWARM add the following section into the .icf file:
       place in RAM_region    { last section FREE_MEM };
    • For MDK-ARM: either define the RW_IRAM1 region in the ".sct" file or modify the line below in tx_initialize_low_level.S to match the memory region being used
        LDR r1, =|Image$$RW_IRAM1$$ZI$$Limit|
    • For STM32CubeIDE add the following section into the .ld file:
        ._threadx_heap :
    {
     . = ALIGN(8);
     __RAM_segment_used_end__ = .;
     . = . + 64K;
     . = ALIGN(8);
    } >RAM_D1 AT> RAM_D1

    The simplest way to provide memory for ThreadX is to define a new section, see ._threadx_heap above. In the example above the ThreadX heap size is set to 64KBytes. The ._threadx_heap must be located between the .bss and the ._user_heap_stack sections in the linker script. Caution: Make sure that ThreadX does not need more than the provided heap memory (64KBytes in this example). Read more in STM32CubeIDE User Guide, chapter: "Linker script".

    • The tx_initialize_low_level.S should be also modified to enable the USE_DYNAMIC_MEMORY_ALLOCATION compilation flag.

NetX Duo usage hints

For more details about the MPU configuration please refer to the AN4838

Keywords

RTOS, ThreadX, NetXDuo, WIFI, Access Point, server-sent events, microSD

Hardware and Software environment

  • This application runs on STM32H747xx devices.

  • This application has been tested with STMicroelectronics STM32H747I-DISCO boards Revision: MB1248-H747I-D02 and can be easily tailored to any other supported device and development board.

  • A daughter board with the WiFi module is to be plugged into the microSD card connector CN12 of the STM32H747I-DISCO board.

  • The daughter board that was used is made up of:

    • A Murata uSD-M.2 Adapter Kit rev A (J1 position 2-3, VBAT from microSD connector)
    • The 1DX M.2 Module for the Cypress WiFi (CYW4343W)

    Connect Pin 20 of STMod+ connector P2 of STM32H747I-DISCO to the uSD M.2 Adapter (J9 pin3 WL_REG_ON_HOST) that supports the Cypress device as described with the below pictures:

picture1

picture2

  • This application uses USART1 to provide a console for commands, the hyperterminal configuration is as follows:

    • BaudRate = 115200 baud
    • Word Length = 8 Bits
    • Stop Bit = 1
    • Parity = None
    • Flow control = None
    • Line endings set to LF (receive).

  • Remote PC Set-up

    • PC must share the same WiFi network configuration from the server on board, i.e., "MyHotSpot" non secure Access Point server with the 192.168.1.1 address.

How to use it?

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

  • Open your preferred toolchain
  • For each target configuration (Nx_HTTP_SSE_wifi_CM4 first then Nx_HTTP_SSE_wifi_CM7) :
    • Rebuild all files
    • Load images into target memory
  • After loading the two images, you have to reset the board in order to boot (Cortex-M7) and CPU2 (Cortex-M4) at once.
  • Run the application with Access Point mode set by default.