AN1633 Datasheet, PDF (1/9 Pages) STMicroelectronics – This application note describes how to implement

AN1633
APPLICATION NOTE
DEVICE FIRMWARE UPGRADE (DFU) IMPLEMENTATION IN
NON-USB APPLICATIONS
1 INTRODUCTION
by Microcontroller Division Applications
This application note describes how to implement the Device Firmware Upgrade (DFU) capa-
bility using a ST7 USB microcontroller like the ST72F62 or ST72F63B in a general purpose or
‘non-USB’ application. The term ’non-USB’ is used here to contrast with ‘USB application’
which has a different DFU implementation (refer to AN1577). In the implementation described
here, the USB interface is not used in the application. The application board is self powered
and the on-chip USB interface is only used occasionally, as a maintenance utility port to up-
grade the MCU firmware.
The USB cell is only activated when the USB cable is plugged-in. At this time the application
is stopped and the microcontroller is seen as a USB device and enters the DFU process to
erase and program the new firmware in Sector 1 and/or Sector 2. When the user removes the
USB cable, the USB cell is switched-off and the main application is executed !
To illustrate this application note, a firmware example has been developed using a ST72F62
or a ST72F63B USB Low-Speed device. This firmware is based on the ST7 USB Low-Speed
DFU Demo firmware.
It is not necessary to know the USB cell to understand this application note. For more informa-
tion about the USB DFU class, please refer to the Application Note AN1577.
AN1633/0303
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