KNOT HAL is part of KNOT project. It aims to provide hardware abstraction layer for SPI and nRF24L01 radios. Allowing power constrained embedded devices to join a wireless network and exchange datagrams using nRF24L01 radios. The initial target platforms are Arduino (nodes), and Raspiberry PI GW. nRF24L01 is a highly integrated, ultra low power (ULP) 2Mbps RF transceiver IC for the 2.4GHz ISM band. On a second project phase, other radio access technologies such as Bluetooth Low Energy, and Wi-Fi are planned.