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STM32F405 "Held in Reset State" Problem

Question asked by kucukgoz.mehmet on Jun 2, 2017

Hi everyone,


I cannot connect the STM32F405RG MCU with ST-Link Utility and IAR Embedded Workbench.


I need your help, 

How can i connect MCU again ?


I tried  

Connection Settings -->   SWD
Mode -->             Connect Under Reset

Reset Mode -->   Hardware Reset,       


and such combinations. (SWD, JTAG, Normal,Hot Plug, Hardware Reset, Core Reset . . .   )


Some of warning messages like this :

"cannot connect to device mcu is kept under reset"

"Target held in reset state"

"Do you want to perform mass erase to unlock the device"

"no MCU device found"



Our circuit of JTAG and MCU connections shown below.


Note : While i cannot connect MCU, RESET_N voltage value is unstable.
sometimes 1v, sometimes 1.7v, sometimes 3v, sometimes 2v  . . always changes ?


my jtag schematic  





my mcu connections



Thank you