The new STM32Cube Low-Layer Application Program Interface (LL API) software from STMicroelectronics allows embedded systems developers to have better access to hardware, down to register-level code for products designed using STM32 ARM Cortex -M microcontroller chips. Embedded system developers can now have flexibility in controlling device peripherals. The LL APIs are integrated into the STM32Cube packages with example projects designed to run on STM32 Nucleo development boards and its also easy to port the examples to other STM32 boards, suggests ST. The LL APIs can be used in parallel with the corresponding HALs in the same project. MISRA-C 2004 compliant LL APIs offer an easy migration path from the older STM32 Standard Peripheral Libraries (SPL) to the STMCube ecosystem. LL APIs are checked using Grammatech CodeSonar for optimum code quality and reliability. The LL APIs are always kept in line with the latest release version through an automatic-update mechanism inside the STM32CubeMX SW package. Free of charge, open-source BSD LL APIs are currently available in the STMCube packages for STM32L4, L0, and F0 MCU series, with full deployment across the STMCube spectrum scheduled for Q1 2017. However there is an exception where HALs and LL APIs can’t be simultaneously used for concurrent processes on the same peripheral.