This is an extension project for the Bluetooth Low Energy Inertial Measurement Unit as described at http://hackaday.io/project/5286-ble-intertial-measurement-unit. Fiddling with prototype cables and switching between breadboard's standard 2.54mm and nRF51822's 2.00mm pitch is a complete nightmare.
I had a similar problem with a Onion Omega2 board, which came in 2mm pin spacing.
I found this cheap proto board on Aliexpress "Prototype PCB for Arduino UNO R3 Shield Board DIY, Combo 2mm + 2.54mm Pitch", which allowed me to make an adaptation between 2mm and 2.54mm:
I had a similar problem with a Onion Omega2 board, which came in 2mm pin spacing.
I found this cheap proto board on Aliexpress "Prototype PCB for Arduino UNO R3 Shield Board DIY, Combo 2mm + 2.54mm Pitch", which allowed me to make an adaptation between 2mm and 2.54mm:
https://fr.aliexpress.com/item/32895744627.html