AN3990 Firmware upgrade overview
Doc ID 022318 Rev 1 3/14
After the board reset and depending on the user button state:
1. User button pressed: The firmware upgrade application is executed.
2. User button not pressed: A test on the user application start address will be
performed and one of the below processes is executed.
– User vector table available: User application is executed.
– User vector table not available: firmware upgrade application is executed.
During the firmware upgrade application execution, there is a continuous check on the user
button pressed state time. Depending on the state time of the user button, one of the
following processes is executed.
Note: The UPLOAD command condition verification is signaled by the blinking state of the blue
LED.
Table 2. User button state time control
User button state Time Process executed
Pressed
> 3 seconds
UPLOAD command will be executed immediately after
completed execution of the DOWNLOAD command.
< 3 seconds Only the DOWNLOAD command is executed.