10.1 Cortex M4 Processor

The Arm®Cortex™-M4 processor is a high performance 32-bit processor designed for the microcontroller market. It offers the following significant benefits to developers:

• Outstanding processing performance combined with fast interrupt handling
• Enhanced system debug with extensive breakpoint and trace capabilities
• Efficient processor core, system, and memories
• Ultra low-power consumption with integrated sleep modes
• Platform security robustness, with integrated memory protection unit (MPU).

The implemented Arm Cortex-M4 is revision r0p1

For additional information, refer to http://www.arm.com.

The Cortex-M4 processor is built on a high-performance processor core with a 3-stage pipeline Harvard architecture, making it ideal for demanding embedded applications. The processor delivers exceptional power efficiency through an efficient instruction set and extensively optimized design, providing high-end processing hardware including IEEE 754-compliant single-precision floating-point computation, a range of single-cycle and SIMD multiplication and multiply-with-accumulate capabilities, saturating arithmetic, and dedicated hardware division.

To facilitate the design of cost-sensitive devices, the Cortex-M4 processor implements tightly-coupled system components that reduce processor area while significantly improving interrupt handling and system debug capabilities. The Cortex-M4 processor implements a version of the Thumb instruction set based on Thumb®-2 technology, ensuring high code density and reduced program memory requirements. The Cortex-M4 instruction set provides the exceptional performance expected of a modern 32-bit architecture, with the high code density of 8-bit and 16-bit microcontrollers.

The Cortex-M4 processor closely integrates a configurable Nested Vector Interrupt Controller (NVIC), to deliver industry-leading interrupt performance. The NVIC includes a Non-Maskable interrupt (NMI), and provides up to 8 interrupt priority levels. The tight integration of the processor core and NVIC provides fast execution of Interrupt Service Routines (ISRs), dramatically reducing interrupt latency. This is achieved through the hardware stacking of registers, and the ability to suspend load-multiple and store-multiple operations. Interrupt handlers do not require wrapping in assembler code, removing any code overhead from the ISRs. A tail-chain optimization also significantly reduces the overhead when switching from one ISR to another.

To optimize low-power designs, the NVIC integrates with the sleep modes, that include a deep sleep function that enables the entire device to be rapidly powered down while still retaining program state.