Unable to connect to chip using SEGGER JLink after flashing firmware

[ubimiles]

We're currently developing a zephyr firmware on zephyr 4.2 and we got a custom board for our hardware powered by an nrf52840-ckaa-R 

the first time I connected the board I was able to flash it using west, 
after flashing the board I am unable to flash it agian  

and I get this error 

Error: One or more batch tasks failed: * 53001714: Device error: Failed to read from memory address 0x10000130: Failed to write DebugPort register 0x08: Unknown Error in J-Link DLL (error code =-1) (Generic)

nrfjprog --recover , nrfjprog --eraseall and nrfuitl device recover all fail to recover the device 

eventually I was able to recover the device by manually issuing the ERASEALL command 

JLinkExe -if SWD -device nRF52840_xxAA -speed 4000

r

w4 4001e504 2
w4 4001e50c 1
w4 4001e514 1
qc

after flashing a few times I started getting failed to power up DAP error whenever I try to connect to the device 

J-Link>con
Device "NRF52840_XXAA" selected.

Connecting to target via SWD
InitTarget() start
InitTarget() end - Took 1.43ms
Found SW-DP with ID 0x2BA01477
DAP: Could not power-up system power domain.
DPIDR: 0x2BA01477
CoreSight SoC-400 or earlier
Scanning AP map to find all available APs
AP[0]: Stopped AP scan as end of AP map has been reached
Iterating through AP map to find AHB-AP to use
Attach to CPU failed. Executing connect under reset.
Failed to power up DAP
InitTarget() start
InitTarget() end - Took 1.24ms
Found SW-DP with ID 0x2BA01477
Failed to power up DAP
Error occurred: Could not connect to the target device.
For troubleshooting steps visit: https://kb.segger.com/J-Link_Troubleshooting

what's weird is one time I got to actually do the eraseall command despite the Failed to power up DAP showing up 

I tried getting the nrf into bootloader mode by holding reset and powering the device up 
I tried lowering speed for JLink 
I tried powering the device and connecting the device, as well as running nrfjprog --recover/--eraseall in a loop while connecting and disconnecting the device 
nothing works out 

hardwarewise the DC/DC converter seems to be working so the nrf is functional (at least to an extent I guess) 
 
Is there any way to debug this or is my device just bricked?

[Vidar Berg]

Hello,

Please check whether your design includes the optional DCDC inductors. The nrf52840dk/nrf52840 build target has this enabled by default, and if you run this firmware on HW without the inductors, the DCDC regulator will fail to provide a stable supply to the chips internal domains which can lead to issues such as being unable to re-program the device.

https://docs.nordicsemi.com/bundle/ps_nrf52840/page/ref_circuitry.html 

Best regards,

Vidar

[ubimiles]

The design does indeed include the DCDC inductors.

I also ended up defining a custom board for Zephyr rather than using that of the nrf52840DK 

[ubimiles]

I can try to supply the 1.3V externally, 

Can you elaborate on how that would be different since I already get 1.25V on DEC4?

[Vidar Berg]

I assume you measured it with a voltmeter. The DEC4 voltage will have ripple and is not constant value when DCDC regulator is enabled and you won't be able to measure this with a voltmeter so I can't tell if it is within spec or not. You also didn't answer my other question about the Vout voltage. 

[ubimiles]

Vout is around 1.8, voltage on reset is around 2.2

[ubimiles]

Still same behavior, getting failed to power up DAP with 1.3V supplied externally to DEC4

[ubimiles]

Here are the ripples on DEC4