What is the meaning of the 51/52 of NRF51/52?

[Andrew]

I am just curious, do the numbers 51 and the 52 have any meaning? Does the base of 50 imply anything? Are these just arbitrary numbers for the sake of good marketing?

[Joakim Jakobsen]

Hi Andrew!

Like the previous answers stated, I'm afraid the numbers in nRF51 and nRF52 does not have any special meaning to them. They are simply product names, made to clearly distinguish between Nordic's product series.

Best regards
Joakim