The Low Level Radio Frequency (LLRF) system will control RF stations in XFEL. The LLRF system interfaces to other subsystems through approximately 100 ADC channels and the same number of DACs. Next generation of the LLRF system for XFEL is based on ATCA standard and the hardware architecture is already fixed. In order to control 32 cavities with amplitude and phase stability at 0.01% and 0.01deg, several control algorithms must run in parallel. Development of software for such complex system requires suitable software development framework which enables implementation of applications running on FPGA, DSP, and processors and communicate to each other through different types of links. The framework should also allow implementation of software for commissioning and later for upgrade. The presented software development framework is a set of rules, coding guidelines, libraries and system firmware. The framework takes into consideration architecture of LLRF hardware including number ATCA shelves, carrier blades and AMC modules for each RF station. The framework also includes libraries for communication links in the ATCA shelf such as PCIe, Ethernet and custom low latency links.