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Unable to run program using VSCode on the STM32F401RET6. "RAMCode did not respond in time"

masoncc
Associate II

‎2025-05-29 5:41 PM - edited ‎2025-05-30 7:54 AM

OS: `Linux Mint 22`
Kernel Version: `6.8.0-48-generic`
STM32CubeMX version: `6.14.1`
STM32 Chip: `STM32F401RET6`

I'm trying to just run a simple light blink script for testing. I'm using a Segger J-Link EDU Mini and programming over SWD using a 10-Pin connection. I'm using a CMake project generated by STM32CubeMX and I am debugging from VSCode (which is launching `JLinkGDBServerCLExe`).

If I run `Start debugging` I get this output (and it just stops there indefinitely):
```
/opt/SEGGER/JLink/JLinkGDBServerCLExe -singlerun -nogui -if swd -port 50000 -swoport 50001 -telnetport 50002 -device STM32F401RE
SEGGER J-Link GDB Server V8.38 Command Line Version

JLinkARM.dll V8.38 (DLL compiled May 28 2025 12:45:51)

Command line: -singlerun -nogui -if swd -port 50000 -swoport 50001 -telnetport 50002 -device STM32F401RE
-----GDB Server start settings-----
GDBInit file: none
GDB Server Listening port: 50000
SWO raw output listening port: 50001
Terminal I/O port: 50002
Accept remote connection: yes
Generate logfile: off
Verify download: off
Init regs on start: off
Silent mode: off
Single run mode: on
Target connection timeout: 0 ms
------J-Link related settings------
J-Link Host interface: USB
J-Link script: none
J-Link settings file: none
------Target related settings------
Target device: STM32F401RE
Target device parameters: none
Target interface: SWD
Target interface speed: 4000kHz
Target endian: little

Connecting to J-Link...
J-Link is connected.
Firmware: J-Link EDU Mini V2 compiled Apr 1 2025 10:05:18
Hardware: V2.00
S/N: 802001278
Feature(s): FlashBP, GDB
Checking target voltage...
Target voltage: 3.31 V
Listening on TCP/IP port 50000
Connecting to target...
Connected to target
Waiting for GDB connection...Connected to 127.0.0.1
GDB client (conn. 10) requested target.xml from GDB Server
Reading common registers: Read register 'r0' (4 bytes) from hardware: 0x00000000
Read register 'r1' (4 bytes) from hardware: 0x00000000
Read register 'r2' (4 bytes) from hardware: 0x00000000
Read register 'r3' (4 bytes) from hardware: 0x00000000
Read register 'r4' (4 bytes) from hardware: 0x00000000
Read register 'r5' (4 bytes) from hardware: 0x00000000
Read register 'r6' (4 bytes) from hardware: 0x00000000
Read register 'r7' (4 bytes) from hardware: 0x00000000
Read register 'r8' (4 bytes) from hardware: 0x00000000
Read register 'r9' (4 bytes) from hardware: 0x00000000
Read register 'r10' (4 bytes) from hardware: 0x00000000
Read register 'r11' (4 bytes) from hardware: 0x00000000
Read register 'r12' (4 bytes) from hardware: 0x00000000
Read register 'sp' (4 bytes) from hardware: 0xD8FFFFFF
Read register 'lr' (4 bytes) from hardware: 0xF9FFFFFF
Read register 'pc' (4 bytes) from hardware: 0xFEFFFFFF
Read register 'xpsr' (4 bytes) from hardware: 0x03000001
Received monitor command: halt
Halting target CPU...
...Target halted (PC = 0xFFFFFFFE)
Received monitor command: reset
Resetting target
Downloading 404 bytes @ address 0x08000000
Downloading 4640 bytes @ address 0x08000194
Downloading 368 bytes @ address 0x080013B4
Downloading 8 bytes @ address 0x08001524
Downloading 4 bytes @ address 0x0800152C
Downloading 4 bytes @ address 0x08001530
Downloading 12 bytes @ address 0x08001534
Writing register 'pc' = 0x08001348
ERROR: Timeout while preparing target, RAMCode did not respond in time (PC = 0xFFFFFFFE, XPSR = 0x01000003, SP = 0x20000610)!
Failed to prepare RAMCode using RAM
Received monitor command: reset
Resetting target
Reading 64 bytes @ address 0x08001240
Read 2 bytes @ address 0x08001250 (Data = 0xB508)
Setting breakpoint @ address 0x08001250, Kind = 2, Type = THUMB, BPHandle = 0x0001
Starting target CPU...
...Target halted (DBGRQ, PC = 0xFFFFFFFE)
Reading common registers: Read register 'r0' (4 bytes) from hardware: 0x00000000
Read register 'r1' (4 bytes) from hardware: 0x00000000
Read register 'r2' (4 bytes) from hardware: 0x00000000
Read register 'r3' (4 bytes) from hardware: 0x00000000
Read register 'r4' (4 bytes) from hardware: 0x00000000
Read register 'r5' (4 bytes) from hardware: 0x00000000
Read register 'r6' (4 bytes) from hardware: 0x00000000
Read register 'r7' (4 bytes) from hardware: 0x00000000
Read register 'r8' (4 bytes) from hardware: 0x00000000
Read register 'r9' (4 bytes) from hardware: 0x00000000
Read register 'r10' (4 bytes) from hardware: 0x00000000
Read register 'r11' (4 bytes) from hardware: 0x00000000
Read register 'r12' (4 bytes) from hardware: 0x00000000
Read register 'sp' (4 bytes) from hardware: 0xD8FFFFFF
Read register 'lr' (4 bytes) from hardware: 0xF9FFFFFF
Read register 'pc' (4 bytes) from hardware: 0xFEFFFFFF
Read register 'xpsr' (4 bytes) from hardware: 0x03000001
Removing breakpoint @ address 0x08001250, Size = 2
Reading register 'msp' = 0xFFFFFFD8
Reading register 'psp' = 0x00000000
```

If I run `Run without Debugging` I get this output:

```
/opt/SEGGER/JLink/JLinkGDBServerCLExe -singlerun -nogui -if swd -port 50000 -swoport 50001 -telnetport 50002 -device STM32F401RE
SEGGER J-Link GDB Server V8.38 Command Line Version

JLinkARM.dll V8.38 (DLL compiled May 28 2025 12:45:51)

Command line: -singlerun -nogui -if swd -port 50000 -swoport 50001 -telnetport 50002 -device STM32F401RE
-----GDB Server start settings-----
GDBInit file: none
GDB Server Listening port: 50000
SWO raw output listening port: 50001
Terminal I/O port: 50002
Accept remote connection: yes
Generate logfile: off
Verify download: off
Init regs on start: off
Silent mode: off
Single run mode: on
Target connection timeout: 0 ms
------J-Link related settings------
J-Link Host interface: USB
J-Link script: none
J-Link settings file: none
------Target related settings------
Target device: STM32F401RE
Target device parameters: none
Target interface: SWD
Target interface speed: 4000kHz
Target endian: little

Connecting to J-Link...
J-Link is connected.
Firmware: J-Link EDU Mini V2 compiled Apr 1 2025 10:05:18
Hardware: V2.00
S/N: 802001278
Feature(s): FlashBP, GDB
Checking target voltage...
Target voltage: 3.31 V
Listening on TCP/IP port 50000
Connecting to target...
Connected to target
Waiting for GDB connection...Connected to 127.0.0.1
GDB client (conn. 9) requested target.xml from GDB Server
Reading common registers: Read register 'r0' (4 bytes) from hardware: 0x00000000
Read register 'r1' (4 bytes) from hardware: 0x00000000
Read register 'r2' (4 bytes) from hardware: 0x00000000
Read register 'r3' (4 bytes) from hardware: 0x00000000
Read register 'r4' (4 bytes) from hardware: 0x00000000
Read register 'r5' (4 bytes) from hardware: 0x00000000
Read register 'r6' (4 bytes) from hardware: 0x00000000
Read register 'r7' (4 bytes) from hardware: 0x00000000
Read register 'r8' (4 bytes) from hardware: 0x00000000
Read register 'r9' (4 bytes) from hardware: 0x00000000
Read register 'r10' (4 bytes) from hardware: 0x00000000
Read register 'r11' (4 bytes) from hardware: 0x00000000
Read register 'r12' (4 bytes) from hardware: 0x00000000
Read register 'sp' (4 bytes) from hardware: 0xD8FFFFFF
Read register 'lr' (4 bytes) from hardware: 0xF9FFFFFF
Read register 'pc' (4 bytes) from hardware: 0xFEFFFFFF
Read register 'xpsr' (4 bytes) from hardware: 0x03000001
Received monitor command: halt
Halting target CPU...
...Target halted (PC = 0xFFFFFFFE)
Received monitor command: reset
Resetting target
Downloading 404 bytes @ address 0x08000000
Downloading 4640 bytes @ address 0x08000194
Downloading 368 bytes @ address 0x080013B4
Downloading 8 bytes @ address 0x08001524
Downloading 4 bytes @ address 0x0800152C
Downloading 4 bytes @ address 0x08001530
Downloading 12 bytes @ address 0x08001534
Writing register 'pc' = 0x08001348
ERROR: Timeout while preparing target, RAMCode did not respond in time (PC = 0xFFFFFFFE, XPSR = 0x61000003, SP = 0x20000610)!
Failed to prepare RAMCode using RAM
Received monitor command: reset
Resetting target
```

According to google that PC value of `0xFFFFFFFE` indicates "core lock-up".

Hopefully this isn't a hardware issue (this is a custom board), but I've been probing with a multimeter and haven't seen anything unexpected so far. There isn't a whole lot going on on the board. `BOOT0` is tied to ground through a 10k resistor.

I made it so that `SystemInit` in `system_stm32f4xx.c` explicitly sets: `SCB->VTOR = FLASH_BASE`, but that didn't seem to change anything.

I saw this post: https://forum.segger.com/index.php/Thread/2635-SOLVED-STM32F746-Failed-to-execute-RAMCode-for-RAM-check-after-upgrade-to-jlink/?postID=9015#post9015 where for them `WWDG_SW` was unset, maybe that is what is happening? I can't say I fully understand that.

As a bit of a side note, at one point I tried setting `WWDG_SW` to 1 using `STM32_Programmer_CLI` using:
```
STM32_Programmer_CLI -c port=SWD -ob WWDG_SW=1
```
And I got back: `Error: No debug probe detected.` Even though `STM32_Programmer_CLI -l` shows:
```
===== J-Link Interface =====

-------- Connected J-Link Probes List --------

J-Link Probe 0 :
J-Link SN : 802001278
-----------------------------------------------
```

Additional information:

My launch configuration:

```
{
"type": "cortex-debug",
"request": "launch",
"name": "Debug J-Link",
"cwd": "${workspaceRoot}",
"executable": "${command:cmake.launchTargetPath}",
"serverpath": "/opt/SEGGER/JLink/JLinkGDBServerCLExe",
"serverArgs": [],
"servertype": "jlink",
"device": "STM32F401RE",
"interface": "swd",
"serialNumber": "",
"runToEntryPoint": "main",
"stm32cubeprogrammer": "${config:STM32VSCodeExtension.cubeCLT.path}/STM32CubeProgrammer/bin",
"armToolchainPath": "${config:STM32VSCodeExtension.cubeCLT.path}/GNU-tools-for-STM32/bin",
"svdFile": "${config:STM32VSCodeExtension.cubeCLT.path}/STMicroelectronics_CMSIS_SVD/STM32F401.svd",
}
```

Thank you for any help, I feel extremely stuck.

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masoncc
Associate II

‎2025-05-30 8:22 AM

With some more sleep, I reviewed the circuit again and noticed that there is nothing connected to the VCAP1 pin. Clearly an error, but would the resulting power instability cause an error like this?

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masoncc
Associate II

‎2025-09-21 2:35 PM - edited ‎2025-09-21 2:55 PM

Current status: I have gone through two board revisions now. I added the VCAP1 pin in the first revision, but the board still doesn't seem to work. This latest board revision gives me test points for every pin of the STM32F401RET6 because I just can't seem to get this basic light blink program to work. I am noticing that NRST is always at 0V with or without the J-Link connected to SWD. I see some people suggesting on the forums to connect a 10k->3.3v pull-up to the NRST pin, but it feels to me like that shouldn't be the fundamental issue considering that isn't something that is suggested in the datasheet.

I've ordered an oscilloscope so I can maybe get some better clue as to what is going on here.

With the board unplugged I did confirm with a multimeter that NRST isn't physically shorted to GND, so something must be pulling it to GND when the board is powered on.

Currently when I run without debugging it halts on `Resetting target`. When I run with debugging it gets to the end (`Starting target CPU...`) but nothing seems to be happening on the board. I have LED blink code running but the voltage of the GPIO pin for both LED pins doesn't change - it sits at around 0.5V, and neither of the LEDs come on.

 

I have also tested using this same J-Link to program my Nucleo board over SWD, and everything worked perfectly. So the code and the programmer are working fine. It has to be the board.

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