When an application implements self reprogramming capability with a bootloader, some method needs to be implemented so as to be able to enter into the bootloader “firmware update mode” (as opposed to the standard application run mode, where self reprogramming is normally not performed).
There are lots of ways to end up in boot loader mode. The examples provided implement two possible methods for entry into boot loader mode:
1. An I/O pin check at power-up/after any reset (ex: a user pressing a pushbutton attached to a general purpose input pin).
2. Software entry from the application run mode, into the bootloader firmware update mode, via an absolute jump to address 0x001C. This can be accomplished by receiving some application specific stimulus (ex: a custom command from a PC GUI program intended to be used in conjunction with the USB application), and then in the firmware, executing an appropriate goto instruction.
Name |
Description |
Discusses hardware entry into boot loader mode. | |
Discusses software entry (entry from application) into boot loader mode. |
MLA - USB Library Help Version : 2.16
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