how to unlock the flash of a nrf51822 using OpenOCD

Question

I bought a couple of nrf51822 but their flash seem to be locked. See the log below:

Licensed under GNU GPL v2
For bug reports, read
    http://openocd.org/doc/doxygen/bugs.html
debug_level: 2

Info : only one transport option; autoselect 'swd'
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : BCM2835 SPI SWD driver
Info : SWD only mode enabled
Info : clock speed 31200 kHz
Info : SWD DPIDR 0x0bb11477
Error: Could not find MEM-AP to control the core   <--- locked flash
Info : Listening on port 3333 for gdb connections

Notes:

• I am using OpenOCD-spi on a Raspberry-pi
• The chip seems to get identified correctly
• I tried setting the unlocking registers for a nrf52 but it didn't work.

How can I unlock it?

Answer 1

Download the cmdline tools from https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPack

if using windows

cd <location of installation>
./nrfjprog -h
./nrfjprog --log 'btlog.txt'
read btlog.txt

this wont unlock it but it will give you insight