9.2 Device Firmware Upgrade Over Serial

Device Firmware Upgrade(DFU) over serial is the functionality in Bootloader that user uses it to load new image received over serial interface and write into the flash. PC GUI tool(MicrochipUtilityTool.exe) and Python Script are two methods used for DFU over serial. The following application guide and demonstration steps use these two methods to carry out the DFU over serial. The demonstration is to upgrade ble_sensor user application with a new image.

MicrochipUtility is a GUI tool, it suppors OTAU over serial, Zigbee OTAU. The utility tool is provided in Microchip website Microchip Utility Tool. For the application guide and demonstration using this tool for the serial DFU, go to Serial Bootloader Demo

Pre-requisite:

• ble_sensor project as current user application(version 1.0.0.0): wireless_apps_pic32cxbz3_wbz35\apps\ble\advanced_applications\ble_sensor\firmware

• Precompiled ble_sensor new image(binary file): wireless_apps_pic32cxbz3_wbz35\apps\ble\advanced_applications\ble_sensor\precompiled_hex\ble_sensor.X.production.signed_uart_1.0.0.1.bin

• Bootloader:

  • Precompiled hex file for GPIO Trigger mode DFU: wireless_apps_pic32cxbz3_wbz35\apps\bootloader\bootloader\precompiled_hex\bootloader.X.production.he

  • Precompiled hex file for Timer Based Trigger DFU: wireless_apps_pic32cxbz3_wbz35\apps\bootloader\bootloader\precompiled_hex\bootloader_timer.X.production.hex

• Python Script Files:

  • For GPIO Trigger mode DFU: flash_load_2ndSlot.py, progctrl.py (wireless_pic32cxbz_wbz\utilities\pic32cx-bz\dfuPythonScripts\)
  • For Timer Based Trigger DFU: flash_load_2ndSlot_timer.py, progctrlOptimized.py (wireless_pic32cxbz_wbz\utilities\pic32cx-bz\dfuPythonScripts\)

• Hardware: WBZ351 Curiosity board

Running a Python Script:

For GPIO Trigger DFU, execute python script using the following command:

python flash_load_2ndSlot.py -i image.bin

For Timer Based Trigger DFU, execute python script by using the following command:

python flash_load_2ndSlot_timer.py -i image.bin

image.bin is the binary file of new user image, this binary file is generated from user application by MPLAB X IDE. It could be other file name from user’s own application, it may have path name before the file.

DFU over Serial Demonstration:

Following are steps to operate DFU over seiral, programing a new user image by using Bootloader.

• Preparation: Create and Program Unified image

Before DFU operation, make sure the unified image containing bootloader and current user application are created and programmed. To do this, open ble_sensor project with MPLAB X IDE. If user click Lodables, will see the bootloader precompiled hex file is already added into the project.

Then on the IDE Tools bar, click Clean and Build Main Project icon to build the project. Since the project has a loadable hex file added, code building will create a unified image hex file ble_sensor.X.production.signed.unified.hex

Note: Another binary file named ble_sensor.X.production.signed.bin is created at the same time. This binary file will be the targe image file used by bootloader for DFU. However, in this demonstration, we will use another precomipled binary file as target image, since that image contains different firmware version to tell user DFU is successful.

Once code building is finished, on the IDE Tools bar, click Make and Program Device Main Project icon to program device, the unified image will be programmed into WBZ351 Curiosity board.

Now the board is ready, followings we will use DFU over serial to upgrade it to a new image ble_sensor.X.production.signed_uart_1.0.0.1.bin

For creating unified image, refer to Bootloader - section Configure User Application to use Bootloader - Add Bootloader as Lodable File/Project to Create Unified Image to know more details.

• Enter into DFU Mode

For the provided bootloader example, DFU mode is triggered by SW2 Button on WBZ351 Curiosity board. So press and hold SW2 Button first, then short press Reset button(SW1) to restart the firmware, the firmware will enter DFU mode. Opening Tera Term on PC, and configure it as 115200/8bit/none Parity/1 Stop bit, will see the message output as “DFU Now!”.

This message means the board is under DFU mode.

• Run Python Script to do DFU

Close Tera Term and open Windows Command Prompt, go to the directory where python script files and binary image file are located and execute python script as below:

python flash_load_2ndSlot.py -i ble_sensor.X.production.signed_uart_1.0.0.1.bin

To run above python script, user may need to copy those python script files and binary image file into a same folder. However, python script also support file with aboslute path name or relative path name.

python flash_load_2ndSlot_timer.py -i ble_sensor.X.production.signed_uart_1.0.0.1.bin

For Timer Based Trigger DFU, it will wait to capture DFU mode window of the bootloader, so for operating Timer Based Trigger DFU, need execute python script first, then reset the board and wait for a while. If python script has captured DFU window, it will start DFU process. Otherwise, user will need another reset the board until DFU is started. Referring to figure below, after python script is executed, it keep waiting and reminding user to reset the board until DFU progress starts to be shown.

The % progress will tell the DFU progress. Once it is finished as 100%, the new image is copied to slot1 of internal flash memory.

• Reset Board to Start New Firmware

Python script has not supported firmware automatical reboot after DFU completion, so need manually reset the board to start new firmware.

Once DFU progress achieves 100% complete, close Windows Command Prompt and open Tera Term to see the message output. On the board, press the Reset button(SW1) to restart, the bootloader will then copy new firmware from flash memory slot1 to slot0. After that, bootloader will jump and start new user image in slot0. On Tera Term, user will see messages as shown below, original firmware version is 1.0.0.0, now firmware version is 1.0.0.1, the DFU is successful.