[CLOSED] J-Link connection problem - STM32

Hello,

I am an engineering student and I’m working on STM32F407ZG.

I use IAR and J-Link Lite STM32.

The basic examples (without RTOS) worked fine until I try other examples (with
FreeRTOS).

Now I can’t download files on the board and an error message “Failed to get CPU
status after 4 retries” is displayed on the screen. The basic examples don’t
work too.

I tried to use another board and JLink recognized the Cortex-M4 processor
whereas the other was unrecognized. ("No device found at all")

I tried to activate the bootloader (pulling BOOTMODE0 low and applying a reset)
but it didn’t work.

After that I tried to use J-Link unlock STM32 but I got another error message.

Thanks for your help,

Best regards,

Andy

SEGGER J-Link Unlock tool for STM32 devices
Compiled Jul 10 2015 18:29:09
(c) 2009-2015 SEGGER Microcontroller GmbH & Co. KG, http://www.segger.com
Solutions for real time microcontroller applications
Options:
[0] Exit
[1] STM32F0xxxx
[2] STM32F1xxxx
[3] STM32F2xxxx
[4] STM32F3xxxx
[5] STM32F4xxxx
[6] STM32L1xxxx
Please select the correct device family: 5
Connecting to J-Link via USB...O.K.
Using SWD as target interface.
Target interface speed: 1000 kHz.
VTarget = 3.274V
Reset target...O.K.
Reset option bytes (may take app. 20 seconds)...Resetting option bytes failed.
Press any key to exit.

Problem is solved ! I had to download the example with the jumper in B0_1 position.
Not reset and return in the B0_0 position and then download the example.

Andy