OTP feature for 51422 / 51822

[mafaka]

Is there a firmware locking feature for either 51422/51822, or can you purchase OTP (one time programmable) versions?

Can you buy them mask programmed from Nordic?

I wish to prevent any reprogramming of the chip in the wild.

Thanks.

[Susheel Nuguru]

The only thing that you can protect on this chip is the readback protection which protects reading back IP from unwanted code sections and/or debugger.

When you use softdevice NVMC is protected peripheral and debugger and or other software cannot directly write to these NVMC (forbidding any erase operations from outside)