Nordic not reflashable suddenly

[dareis08]

Nordic,

We've been using the nRF52832 for many years now.  We have a custom board that uses SWCLK and SWDIO to flash our NRF52.  We're getting set for production and I am working on our automated manufacturing rig.  We have a python script that flashes a nordic with a soft device, bootloader, and then application.  Some of the GPIO go to LEDs, so I can see what state the chip is in after programming.  It had been working great then I started getting this problem where the LEDs didn't show up in the right state.  I'd go to reflash the device, and then the SWD won't connect, and I could not erase the chip.  I can hit our reset button, tied to the RESET pin on the IC, and nothing happens.  Normally this button does a hard reset, where the LED goes away and (I believe) the chip loses power.  Upon release of the reset, the board should initialize into the bootloader and the LED blinks red marking as such.  But for these 'bricked' boards, the LED stays on throughout the reset button press.   These two things: not able to reset the chip, and not being able to reflash the chip, these are quite alarming.

One piece of good news is the current drawn seems to be about 1 mA like when the Nordic is in low power state.  

I've spent most all day going through devzone forums trying things, hoping to recover or at least explain my freeze-up.  

When I go back into J Flash Lite, I can no longer ERASE the chip.  Now it says

Connecting to J-Link...
Connecting to target...
ERROR: Could not connect to target.
Done.

Fine, I can try from the command utility.  I use the jlink.exe tool, and go through the regular steps to connect and then try to erase.  This also doesn't work:

J-Link>connect
Device "NRF52832_XXAA" selected.

Connecting to target via JTAG
InitTarget() start
InitTarget() end
TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
InitTarget() start
InitTarget() end
TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
InitTarget() start
InitTarget() end
TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
InitTarget() start
InitTarget() end
TotalIRLen = ?, IRPrint = 0x..000000000000000000000000
Cannot connect to target.

Ok, now I try to use the nrfjprog tool.  For reference I look up the version as 

nrfjprog version: 10.15.1 external
JLinkARM.dll version: 7.58b

Then I do all kinds of commands to try and talk to my board.  Here are some

>nrfjprog --recover --log
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: [ nRFXX] - Device does not have an ARM debug port.
ERROR: [SeggerBackend] - JLinkARM.dll reported "-1", "An unknown error.".
ERROR: nrfjprog could not identify the target device. This may be due to an
ERROR: invalid family argument, a problem with your device, or nrfjprog may
ERROR: not yet support your device.
ERROR: Please check the family argument passed, or upgrade nrfjprog to a more
ERROR: recent version.

>nrfjprog -e
ERROR: nrfjprog could not identify the target device. This may be due to an
ERROR: invalid family argument, a problem with your device, or nrfjprog may
ERROR: not yet support your device.
ERROR: Please check the family argument passed, or upgrade nrfjprog to a more
ERROR: recent version.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.

>nrfjprog -d --family nrf52 --log
ERROR: Unable to connect to a debugger.
ERROR: [ nRF52] - Debug probe is not connected to an NRF52 series device.
ERROR: The --family option given with the command (or the default from
ERROR: nrfjprog.ini) does not match the device connected.

I know the segger and cables and everything are correct, I HAD been able to program this and other boards.  But during development of the python script, I've 'bricked' 5 of my boards.  I only have 2 left.  So I need to get to the bottom of this.

I don't understand how something could ever make the SWCLK SWDIO not able to erase the chip.  What am I missing, please help.

environment:  windows 10

[dareis08]

hmolesworth,

In response to your comment about the LED.  Here is that section of the schematic.  I'm not sure the LED staying on after a reset is the problem.  The LED are connected to GPIO and then programmed for funcationality in our program.  So, with an empty memory, I think the datasheet shows these are reset as input pins.  My guess is that this causes the LED to be HIGH when the board is bricked, and even while the P0.21 pin reset is toggled.  

The fact that even after the erase command, where the system clears the settings of the reset (I think) and does a system reset to 'enact' the new UICR values, even after this I still need the 3V external in order for the chip connect.  That is suspicious.  As a side note, after this erase, the LEDs are all off so long as the 3V external is applied.  When I take off the external, the LEDS go back on and the board cannot connect to nrfjprog.

 

nrfjprog -f nrf52 -e
Erasing user available code and UICR flash areas.
Applying system reset.

Can you please explain more what you would suggest we do with the supply current to further debug?

Thanks,

Darren

[hmolesworth]

LED on during reset pin low implies no internal VCC available even if voltage is on the VCC pin so instead internal VCC is coming from the LED pin through the schottky protection diode to internal VCC and thus illuminating the LED; if the chip were in reset the LED port pin would not be driven low at all and would not be lit. This implies the internal LDO (or DCDC if that is hat you are using) may be bust. Try enabling the internal DCDC at powerup  then remove the 3 volts on the reset pin and see if the it still dies.

Otherwise we are quite sure there isn't a simple code bug? Check by while(1); at power up, no other code run at all; no offense intended.

Edit: Just to clarify (couldn't edit my last post, still issues with this forum in editing) the thesis is that the Reset pin has become the new source of VCC for the nRF52, nothing to do with reset functionality. Any other i/o pin might also supply VCC if it were directly connected to 3 volts, then maybe the reset pin (now not connected to 3 volts) would work also as expected. Worth a try .. if this the case the current into the Reset or other io pin will be (say) 4 or 5mA since it is supplying the entire internal VCC. How could this have happened? Well ..