ST STM32F105 series Application Note

AN2662 DFU bootloader
Doc ID 14156 Rev 1 67/83
4 DFU bootloader
4.1 Bootloader code sequence
Figure 52. Bootloader for STM32F105xx and STM32F107xx with USB DFU
1. After system reset, the device may return to the BL_DFU loop, enter the USART or CAN bootloader loops
or execute code from Flash/RAM depending on the connection states and the boot pins status.
2. Leave DFU is achieved by a 0 Data Download request followed by GetStatus request and Device Reset.
3. After six trials (the three clock configurations are tested twice), a System Reset is generated.
BL_DFU
Received
correct Packet?
No (Timeout)
Ye s
Configure external oscillator
mode and re-initialize USB
Enumeration Phase
Enter DFU Mode
Wait for
Host commands
DFU Request
routines
DFU requests
Jump to
Leave DFU
routine
Leave DFU
Generate System
and exit DFU mode
Need reset ?
Reset
1)
Application Address
Ye s
No
Mode
2)
Configure internal oscillator
mode and re-initialize USB
USB Device
connected
No
Ye s
Device USB reset
Clock Detection
Phase
3)
Increment TrialNum
TrialNum > 6
Generate System
Reset

ST STM32F105 series Specifications

General

Brand	ST
Model	STM32F105 series
Category	Microcontrollers
Language	English