Posts by John1234

Hello,

I tried your second suggestion and it didn't work. I used a multimeter to check the voltage of the SWDIO and SWDCLK signals, I get 0.16V and 0.5V respectively. Does this tell you something?

I tried connecting the J-link EDU mini to my target board via SWD and it can seem to connect. The target board is a custom PCB which features the STM32F401RDT6 microcontroller. I connect the SWDIO and SWDCLK pins together, also the ground and VRef pin. This is what I get as the output :

Output

SEGGER J-Link Commander V7.94c (Compiled Jan 3 2024 15:17:49)
DLL version V7.94c, compiled Jan 3 2024 15:17:37

Connecting to J-Link via USB...O.K.
Firmware: J-Link EDU Mini V1 compiled Dec 13 2023 14:36:33
Hardware version: V1.00
J-Link uptime (since boot): 0d 00h 05m 24s
S/N: 801043014
License(s): FlashBP, GDB
USB speed mode: Full speed (12 MBit/s)
VTref=3.265V

Type "connect" to establish a target connection, '?' for help
J-Link>connect
Please specify device / core. <Default>: STM32F401RD
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 "STM32F401RD" selected.

Connecting to target via SWD
InitTarget() start
SWD selected. Executing JTAG -> SWD switching sequence.
Error: Failed to initialized DAP.
Can not attach to CPU. Trying connect under reset.
SWD selected. Executing JTAG -> SWD switching sequence.
Error: Failed to initialized DAP.
Connecting to CPU via connect under reset failed.
InitTarget() end - Took 309ms
Connect failed. Resetting via Reset pin and trying again.
InitTarget() start
SWD selected. Executing JTAG -> SWD switching sequence.
Error: Failed to initialized DAP.
Can not attach to CPU. Trying connect under reset.
SWD selected. Executing JTAG -> SWD switching sequence.
Error: Failed to initialized DAP.
Connecting to CPU via connect under reset failed.
InitTarget() end - Took 209ms
Cannot connect to target.

Any help would be greatly appreciated.