STM32L471 not getting detected in SWD/JTAG (STLINK).

[SMano]

I have two STM32L471 custom design board. Both of them are not getting detected with stlink neither via jtag not swd. But, i am able to program the flash using the bootloader mode. Is there any way to recover the swd/jtag. I need at least one of them for debugging. I have attached the screen shots.

Appreciate your help.

Following is the log data

18:23:14 : Can not connect to target!

         If you're trying to connect to an STM32W1xx device, please select Normal or HotPlug mode from Target->Settings menu.

         If you're trying to connect to a low frequency application , please select a lower SWD Frequency mode from Target->Settings menu.

18:23:15 : No target connected

[Tesla DeLorean]

Have you tried via "Connect Under Reset"? Requires NRST wired to debugger header.

Have you tried with BOOT0 pulled HIGH?

Review circuit.

Make sure you have the right pins connected, as the error generally means not connected correctly or not powered.

Perhaps test pins via toggling of GPIO (PA13,PA14) in code you upload via the bootloader.

[SMano]

Hi Clive,

Debugger connection is proper, since i used to debug earlier. All of a sudden, i am unable to debug using both jtag/swd.

Have you tried with BOOT0 pulled HIGH?

I pulled BOOT0 pin high to enter in the bootloader mode and able to program the flash. Application runs properly.

Perhaps test pins via toggling of GPIO (PA13,PA14) in code you upload via the bootloader.

I configured the pins PA13 and PA14 as output and toggled it. It works fine.

With oscilloscope, i could observe the reset pin going down multiple times, when tried to connect under reset. Also observed four pulses in SWDCLK.