2022-12-01 05:35 AM
My previous question was how to detect a cable and they said to use a EXTI to receive a VBUS detection. The customer wants to use USB to program a blank device (so nothing configured) and EXTI is a block of interrupts and could be multiple pins. Please provide more details on how the bootloader checks for a USB cable.
Thanks,
Sonya
2022-12-01 06:35 AM
I think they can monitor voltage levels on the DP/DM pins at the USB IO Cell.
Unconnected state determined by pull-ups.
2022-12-01 07:00 AM
Read AN2606
2022-12-01 07:54 AM
I have read AN2606, but it does not tell you how the bootloader detects that a USB cable is detected. We know how to detect a USB cable is connected, but can't find details on how the bootloader recognizes the connection.
2022-12-01 08:46 AM
For what you need it. System bootloader or any other use USB standart for init communication.
I use it two way. One is device powered .. connect USB cable .. reset MCU with boot0 pin ...
Second not powered device , schematics that pull power from USB and set boot0 pin
and exist more ...