Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

DannyB — Wed, 11 Nov 2020 23:34:27 GMT

Also, now I can't seem to duplicate the problem. (I tried a couple times on each board)

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

DannyB — Wed, 11 Nov 2020 23:30:23 GMT

Ok, I was able to recover both boards. I had to apply power to the nRF as I was calling:

nrfjprog --recover --family NRF52

But I still don't know the root cause for the problem. Is it possible the nrfjprog --eraseall put the pin pselreset UICR registers in a weird state? Also, these nRFs had probably never been programmed/erased before i did it.

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

DannyB — Wed, 11 Nov 2020 21:29:47 GMT

Here is the log from a failing board:

...

Connecting to J-Link...

J-Link is connected.

Firmware: J-Link V9 compiled Dec 13 2019 11:14:50

Hardware: V9.10

S/N: 59103743

Feature(s): GDB

Checking target voltage...

Target voltage: 1.80 V

Listening on TCP/IP port 2331

Connecting to target...

ERROR: Could not connect to target.

Target connection failed. GDBServer will be closed...Restoring target state and closing J-Link connection...

Shutting down...

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

DannyB — Wed, 11 Nov 2020 21:26:24 GMT

Interesting, I believe the programmer works at 1.8 V, but I don't know for sure. I am able to use this JLink on boards I haven't erased. Here is the log of a successful debug session:

SEGGER J-Link GDB Server V6.86f Command Line Version

JLinkARM.dll V6.86f (DLL compiled Oct 23 2020 17:50:09)

Command line: -if swd -device nRF52840_xxAA -endian little -speed 1000 -port 2331 -swoport 2332 -telnetport 2333 -vd -ir -localhostonly 1 -singlerun -strict -timeout 0 -nogui

-----GDB Server start settings-----

GDBInit file: none

GDB Server Listening port: 2331

SWO raw output listening port: 2332

Terminal I/O port: 2333

Accept remote connection: localhost only

Generate logfile: off

Verify download: on

Init regs on start: on

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: nRF52840_xxAA

Target interface: SWD

Target interface speed: 1000kHz

Target endian: little

Connecting to J-Link...

J-Link is connected.

Firmware: J-Link V9 compiled Dec 13 2019 11:14:50

Hardware: V9.10

S/N: XXXXXXXX

Feature(s): GDB

Checking target voltage...

Target voltage: 1.79 V

Listening on TCP/IP port 2331

Connecting to target...

Connected to target

Waiting for GDB connection...Connected to 127.0.0.1

Reading all registers

Read 4 bytes @ address 0x00000000 (Data = 0x20040000)

Read 2 bytes @ address 0x00000000 (Data = 0x0000)

Received monitor command: speed 1000

Target interface speed set to 1000 kHz

Received monitor command: clrbp

Received monitor command: reset

Resetting target

Received monitor command: halt

Halting target CPU...

...Target halted (PC = 0x00000100)

Received monitor command: regs

R0 = 00000000, R1 = 00000000, R2 = 00000000, R3 = 00000000

R4 = 00000000, R5 = 00000000, R6 = 00000000, R7 = 00000000

R8 = 00000000, R9 = 00000000, R10= 00000000, R11= 00000000

R12= 00000000, R13= 20040000, MSP= 20040000, PSP= 00000000

R14(LR) = FFFFFFFF, R15(PC) = 00000100

XPSR 01000000, APSR 00000000, EPSR 01000000, IPSR 00000000

CFBP 00000000, CONTROL 00, FAULTMASK 00, BASEPRI 00, PRIMASK 00

Reading all registers

Received monitor command: speed auto

Select auto target interface speed (2000 kHz)

Received monitor command: flash breakpoints 1

Flash breakpoints enabled

Received monitor command: semihosting enable

Semi-hosting enabled (Handle on BKPT)

Received monitor command: semihosting IOClient 1

Semihosting I/O set to TELNET Client

Received monitor command: SWO DisableTarget 0xFFFFFFFF

SWO disabled successfully.

Received monitor command: SWO EnableTarget 0 0 0x1 0

SWO enabled successfully.

Downloading 16032 bytes @ address 0x0000C020 - Verified OK

Downloading 16064 bytes @ address 0x0000FEC0 - Verified OK

Downloading 16016 bytes @ address 0x00013D80 - Verified OK

Downloading 16064 bytes @ address 0x00017C10 - Verified OK

Downloading 16096 bytes @ address 0x0001BAD0 - Verified OK

Downloading 15872 bytes @ address 0x0001F9B0 - Verified OK

Downloading 16096 bytes @ address 0x000237B0 - Verified OK

Downloading 16064 bytes @ address 0x00027690 - Verified OK

Downloading 16064 bytes @ address 0x0002B550 - Verified OK

Downloading 16016 bytes @ address 0x0002F410 - Verified OK

Downloading 16032 bytes @ address 0x000332A0 - Verified OK

Downloading 16320 bytes @ address 0x00037140 - Verified OK

Downloading 2224 bytes @ address 0x0003B100 - Verified OK

Downloading 24 bytes @ address 0x0003B9B0 - Verified OK

Downloading 2200 bytes @ address 0x0003B9C8 - Verified OK

Comparing flash [....................] Done.

Writing register (PC = 0x c120)

Read 4 bytes @ address 0x0000C120 (Data = 0x0000F04F)

Read 2 bytes @ address 0x0000C120 (Data = 0xF04F)

Read 2 bytes @ address 0x0000C122 (Data = 0x0000)

Read 2 bytes @ address 0x0000CA8C (Data = 0xB508)

Reading 64 bytes @ address 0x0002B980

Read 2 bytes @ address 0x0002B9B2 (Data = 0xF7E1)

Received monitor command: regs

R0 = 00000000, R1 = 00000000, R2 = 00000000, R3 = 00000000

R4 = 00000000, R5 = 00000000, R6 = 00000000, R7 = 00000000

R8 = 00000000, R9 = 00000000, R10= 00000000, R11= 00000000

R12= 00000000, R13= 20040000, MSP= 20040000, PSP= 00000000

R14(LR) = FFFFFFFF, R15(PC) = 0000C120

XPSR 01000000, APSR 00000000, EPSR 01000000, IPSR 00000000

CFBP 00000000, CONTROL 00, FAULTMASK 00, BASEPRI 00, PRIMASK 00

Reading all registers

Read 4 bytes @ address 0x0000C120 (Data = 0x0000F04F)

Read 2 bytes @ address 0x0000C120 (Data = 0xF04F)

Read 2 bytes @ address 0x0000C122 (Data = 0x0000)

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

Jørgen Holmefjord — Wed, 11 Nov 2020 19:38:29 GMT

[quote user="DannyB"]I am using an external Segger JLink USB-based programmer.[/quote]

Have you made sure that this programmer supports the voltage level your board is running at?

[quote user="DannyB"]However, I did try with the Segger onboard the DK and it was the same result[/quote]

This makes sense if the custom board runs at 1.76V. The on-board debugger on the DK does not support level-shifting, meaning it can only program boards running at the DK voltage (normally 3.0 V).

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

DannyB — Wed, 11 Nov 2020 17:53:29 GMT

I am using an external Segger JLink USB-based programmer. However, I did try with the Segger onboard the DK and it was the same result (still unable to communicate with the target).

The custom board is powered by an onboard PMIC, Vbat = 3.8 Volts. It is generating a Vdd of 1.76 Volts.

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

Jørgen Holmefjord — Wed, 11 Nov 2020 14:41:52 GMT

Hi,

How is the custom board connected to the debugger? Are you using the on-board debugger on the DK?

When you say "Voltage looks good", what does this mean exactly? Is the custom board powered from the DK, at the same voltage level, or is it powered externally?

Best regards,
Jørgen

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

DannyB — Tue, 10 Nov 2020 23:35:55 GMT

I'm wondering if its a problem if the GPIO_AS_PINRESET is not set. Would this cause the SWD interface to have a problem if PINRESET is not defined in UICR?

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

DannyB — Tue, 10 Nov 2020 22:48:53 GMT

I've tried a fair amount of these and none of them helped.

RE: Unable to connect to nRF52840 on custom board over SWD. "No idcode detected:

awneil — Tue, 10 Nov 2020 22:38:13 GMT

Segger has this on debugging target connection problems:

wiki.segger.com/J-Link_cannot_connect_to_the_CPU