connection fail via swd with jlink

[bini2007]

We're using nrf52833 and our target board is already running our program well.

Then 

we'd like to flash by using Jlink SWD programmer.

So, we connected vref, gnd, swdio swclk pin between our target and jlink's 20 pin connector by wire.

When we use jlink flasher program, we got the following errors.

Connecting to target via SWD
InitTarget() start
InitTarget()end
RESET (pin15) high, but should be low. Please check target hardware.
RESET (pin15) high, but should be low. Please check target hardware.
RESET (pin15) high, but should be low. Please check target hardware.
RESET (pin15) high, but should be low. Please check target hardware.
RESET (pin15) high, but should be low. Please check target hardware.
RESET (pin15) high, but should be low. Please check target hardware.
RESET (pin15) high, but should be low. Please check target hardware.
InitTarget() start
InitTarget() end
RESET (pin15) high, but should be low. Please check target hardware.
RESET (pin15) high, but should be low. Please check target hardware.
Cannot connect to target.

It seems errors in connection nrf52833 and jlink.

Currently, our target don't use RESET pin (p0.18) after looking into our schematic.

please check and advice us.

[Menon]

Hello,

From your response, I understand that the issue occurs when you use an external debugger, but there is no issue when using the nRF52833 DK as the debugger. Please correct me if I’m wrong.

If that is the case, the problem is likely related to the connection between your J-Link debugger and your custom board. Could you please ensure that the power supply is stable while using the external debugger?

From the last shared logs, it appears that the target device is not being detected.

Kind Regards,

Abhijith

[bini2007]

Hi,

I have tested j-link connection between our target and DK board.

When DK board was connected with RTT Viewer on my PC, the noti message with "update on Jlink OB fw"showed on RTT Viewer.

And I update Jlink OB on my DK board and I tested again j-link via swd with my target.

Then the following errors happened. please advice me why this happened and jlink OB connection failed even with our target.

C:\Program Files\SEGGER\JLink_V794e>JLink.exe
SEGGER J-Link Commander V7.94e (Compiled Jan 15 2024 15:20:36)
DLL version V7.94e, compiled Jan 15 2024 15:18:46

Connecting to J-Link via USB...O.K.
Firmware: J-Link OB-SAM3U128-V2-NordicSemi compiled Oct  9 2024 11:00:56
Hardware version: V1.00
J-Link uptime (since boot): 0d 00h 02m 58s
S/N: 685079944
License(s): RDI, FlashBP, FlashDL, JFlash, GDB
USB speed mode: High speed (480 MBit/s)
VTref=3.300V


Type "connect" to establish a target connection, '?' for help
J-Link>connect
Please specify device / core. <Default>: NRF52833_XXAA
Type '?' for selection dialog
Device>
Please specify target interface:
  J) JTAG (Default)
  S) SWD
  T) cJTAG
TIF>S
Specify target interface speed [kHz]. <Default>: 4000 kHz
Speed>
Device "NRF52833_XXAA" selected.


Connecting to target via SWD
InitTarget() start
InitTarget() end - Took 108ms
Connect fallback: Reset via Reset pin & Connect.
InitTarget() start
InitTarget() end - Took 109ms
Cannot connect to target.
J-Link>

Please help me.