AN1577 Datasheet, PDF (1/30 Pages) STMicroelectronics – This application note presents the implementation

AN1577
APPLICATION NOTE
DEVICE FIRMWARE UPGRADE (DFU) IMPLEMENTATION IN
ST7 USB DEVICES
by Microcontroller Division Applications
1 INTRODUCTION
This application note presents the implementation of a Device Firmware Upgrade (DFU) ca-
pability in ST7 USB microcontrollers. It follows the DFU class specification defined by the USB
Implementers Forum, for reprogramming an application through USB. The DFU principle is
particularly well suited to USB applications that require need to be reprogrammed in the field:
The same USB connector can be used both for the standard operating mode, and for the re-
programming process.
This operation is made possible by the IAP capability featured by most of the ST7 microcon-
trollers, which allows a FLASH MCU to be reprogrammed by any communication channel
(Please refer to AN1575 for more details).
The DFU process, like any other IAP process, is based on the execution of firmware located in
Sector 0 of the ST7 Flash memory which manage the Flash operations (erasing and program-
ming) of Sectors 1 and 2.
This application note covers then two main aspects:
The firmware located in Sector 0,
The Interface between the firmware in Sector 0 and the firmware in Sectors 1 & 2.
The proposed implementation is demonstrated with 2 different projects: the USB Low-Speed
devices Evaluation Kit and the ST7265 Full-Speed 5-in-1 demoboard. In this document these
projects are referred to as “LS project” and “FS project”.
A basic DFU protocol is also used in these projects. The modular approach used in the imple-
mentation based on a DFU library allows you to adapt it easily to other higher level protocols
or new types of hardware.
AN1577/0103
1/30
1