NRF52 DK won't work well for some bluetooth examples in zephyr project

[summer]

I choose one NRF52 DK(nrf52840_pca10056) for my daily development. After hundreds of erase and write cycles, the DK won't behaves like it should do. The other DKs runs well while this one not. But some basic example runs well. How can I figure out if this DK is damaged? If so, why is it damaged partially?

what I have tested is, zephyr ibeacon sample works well, while peripheral sample wont work as expected. But other DKs work well.

[Stian Røed Hafskjold]

The DK may have been ESD damaged after a lot of use. You can also try to verify the contents of the flash after programming using 'nrfjprog --verify' command to see if the flash memory is bad.

[summer]

I have verified the content flashed into the DK, and everything seems ok. But the board behaves incorrectly.

[Stian Røed Hafskjold]

Ok good. Then step 2 is to explain what "behaves incorrectly" means.

[summer]

peripheral sample output

***** Booting Zephyr OS zephyr-v1.13.0-3079-g4e23d6c875 *****
Bluetooth initialized
[00:00:01.514

and it is stuck at
static inline void cpu_sleep(void)
{
__WFE();
__SEV(); // it stucks here
__WFE();
}

the ibeacon log using the same DK is

***** Booting Zephyr OS zephyr-v1.13.0-3099-g35da3e3e0f *****
Starting iBeacon Demo
Bluetooth initialized
[00iBeacon started
:00:00.007,415] bt_hci_core: HW Platform: Nordic Semiconductor (0x0002)
[00:00:00.007,415] bt_hci_core: HW Variant: nRF52x (0x0002)
[00:00:00.007,415] bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 1.13 Build 99
[00:00:00.007,843] bt_hci_core: Identity: e9:08:a3:ee:25:67 (random)
[00:00:00.007,843] bt_hci_core: HCI: version 5.0 (0x09) revision 0x0000, manufacturer 0x05f1
[00:00:00.007,843] bt_hci_core: LMP: version 5.0 (0x09) subver 0xffff

and I can see the beacon using my phone.

In short, the program is stuck at some random point but other DKs work well.

[Stian Røed Hafskjold]

If the FW works on another DK with the same chip version, I'm pretty sure the chip is ESD damaged.