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.

Working with the zip version

If you decide to work with the zip version, complete the following steps to set up your environment:

1. Download the repository file nRF51_SDK_x.x.x_xxxxxxx.zip (for example, nRF51_SDK_9.0.0_1a2b3c4.zip) from https://developer.nordicsemi.com.
2. Extract the zip file to the directory that you want to use to work with the nRF51 SDK.
3. Install the nRF51 MDK:
   • If you use Keil 5, Keil will prompt you to install the nRF_DeviceFamilyPack.
   • If you use Keil 4, double-click the nRF5x_MDK_x_x_x_Keil4.msi file to install the MDK.
   • If you use IAR, double-click the nRF5x_MDK_x_x_x_IAR.msi file to install the MDK.
   • If you use GCC, the MDK is delivered with the SDK and does not need to be installed separately.

Installing CMSIS Packs

To install all CMSIS Packs for the nRF51 SDK for the first time, complete the following steps:

1. Download the packs file nRF51_SDK_x.x.x_xxxxxxx_packs.zip (for example, nRF51_SDK_9.0.0_1a2b3c4_packs.zip) from https://developer.nordicsemi.com.
2. Extract the .zip file to a temporary directory, for example C:\tmp\nRF51_SDK.
3. Run the install.bat file that is located in the extracted directory and follow the instructions.

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.