Before you install the SDK, make sure that you have all required tools installed. See section 3 (Getting started) in the nRF51 Development Kit User Guide for detailed instructions.
The SDK is delivered both as CMSIS Packs and as a plain zip archive. If you use Keil 4, Keil 5 before V5.12, or a different IDE that uses GCC or IAR, work with the zip version. If you use Keil 5.12 or later, you can either work with the zip version or install the CMSIS Packs.
If you decide to work with the zip version, complete the following steps to set up your environment:
To install all CMSIS Packs for the nRF51 SDK for the first time, complete the following steps:
C:\tmp\nRF51_SDK
.After the installation, you can access the components and examples from the Keil Pack Installer. Alternatively, you can install the packs directly from the Pack Installer.
To update to newer versions of the SDK, click the Check For Updates button in the Pack Installer and select which packs you would like to update.