Problem to debug NET CPU after segger update and new nrf5340 chip

[emag nioj]

Hi i  m evaluating the nrf5340 and i get this message when i try to download the code to NET cpu and it's a bit impossible to attach the debugger

CTRL-AP indicates that the device is secured.

For debugger connection the device needs to be unsecured.
Note: Unsecuring will trigger a mass erase of the internal flash, SRAM and UICR of both the application and the network core.

How to unsecure permanently?

Thank you!

[Elfving]

Hi Emag!

Correct, the nRF53 series (and soon the nRF52's) comes with APPROTECT being enabled as default. It is basically read/writing protected until it is programmed not to be. In order to circumvent this temporarily however you can recover it:

nrfjprog --recover --coprocessor CP_NETWORK
nrfjprog --recover

To unsecure "permanently" (ie. having it disabled after flashing) you need to write to

UICR.APPROTECT and CTRL-AP.APPROTECT.DISABLE

for both the app and network core. Though this wouldn't really be permanent either, as flashing anything like a sample project can revert it back to the default. For more info about this see here.

Best regards,

Håkon

[emag nioj]

Thank you Elfving,  so if i put in the NET Code at main this 

NRF_UICR_NS->APPROTECT=0x50fa50fa;
NRF_CTRLAP_NS->APPROTECT.DISABLE=0x50fa50fa;

and in APP code at main this 

NRF_UICR_S->APPROTECT=0x50fa50fa;
NRF_CTRLAP_S->APPROTECT.DISABLE=0x50fa50fa;

do you think it can solve and let me attach the debugger to see the code?

I need to debug the NET core because after a while i stop the RTC0 and put the core to _WFI waiting an accelerometer interrupt to wake up.

But after the GPIOTE interrupt i try to restart RTC0 but the counter seems very slow i haven't RTC0 interrupts.

Now the workaround is to NVIC_DisableIRQ(RTC0_IRQ) and NVIC_EnableIRQ(RCT0_IRQ) when wake up.

In the previous chip this problem was not present. So now with the default APProtect is a caos to debug when i try to attach the memory is erased.

Best regards,
emag