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STM32 Leave DFU mode command

Question asked by Kulkarni.Narendra on Jan 23, 2017
Latest reply on May 15, 2018 by wong.chii_lok

Hi, I have a question regarding STM32L Leave DFU mode command. I can enter in to built in bootloader from startup code. I am initialising some GPIO pins in startup (assembly code) and they maintain the status after I push the uC in boot ROM. However, after completion of downloading new firmware, when the application sends Leave DFU mode command, the device comes out successfully but the GPIO registers are are at default state. I understand that application address needs to be provided before sending 0 length packet (leave dfu command).  The documentation (AN3156 page 20) indicates 'the device disconnects itself', but it is unclear if it initializes all peripherals to default state. The GPIO status is maintained while I enter from my startup code to bootrom code.

Can anybody throw some light on how the DFU exit is handled in bootcode or indicate correct steps so that it does not affect the GPIO status. 

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