Improve Cortex M4 MCU interrupt responses with an intelligent Peripheral Event System
Advantages of peripheral event control
The SAM4L uses Atmel proprietary low power embedded Flash and the latest semiconductor processes and several architectural refinements to deliver industry-leading energy efficiency in both active and sleep modes (Figure 3 below).
Additional energy saving are realized thanks to its SleepWalking mode, the SAM4L is able to spend a greater percentage of its time in a deep sleep while the Peripheral Event System handles most routine tasks. The PES’s autonomous peripherals only enter their active mode when an event occurs which meets their pre-programmed trigger criteria (Figure 4 below).
When used in conjunction with the Cortex M4 CPU’s low operating power and rapid wake-up characteristics, the SAM4L produces a dramatically smaller energy footprint than conventional MCUs while delivering superior 32-bit performance for conventional and real-time applications.
*The Peripheral Event System execute its functions in 2 clock cycles, enabling event processing with deterministic latency without an RTOS.
*The PES’s low-latency event handling provides reliable fault detection with 100% predictable reaction time.
*Autonomous peripherals simplify, and in many cases, eliminate complex interrupt routines for cleaner, less fragile code and shorter development/debug cycles.
*Simplified software with less real-time dependencies retires risk in software development and update cycles.
*Designs are simper to implement and test.
*Intelligent peripherals reduce CPU’s overhead load, freeing processor resources for use in other applications or features.
Conclusion
Embedded systems designers face a daunting set of challenges as the products they design are expected to deliver more intelligence and increased functionality, often on a very limited power budget.
Microcontrollers equipped with a network of autonomous peripherals, such as the Peripheral Event System (PES) can help designers meet those challenges by autonomously performing complex functions such as data collection, timing, and communication, as well as respond to real-time events without involving the device’s main processor.
This distributed network of intelligent analog and digital I/O peripheral elements which operates independently of the CPU and its DMA system and can be configured to have its peripherals selectively react to external inputs and interact with each other without using any CPU resources.
In addition to dramatically reducing the MCU’s energy consumption, the PES eliminates the need for most interrupt service routines (ISRs), enabling deterministic response to real-time events and greatly simplifying software development.
The Peripheral Event System’s basic architecture has already been used in Atmel’s AVR XMEGA series of 8-bit processors and in the 32-bit AVR UC3, and has recently been incorporated in Atmel’s SAM4L Cortex M4-based 32-bit MCU family.
This new family of PES-augmented MCUs brings powerful real-time capabilities, ultra-low-power operation, and simplified programming to applications such as intelligent sensor nodes for HVAC & alarm systems, glucose monitors, and point-of-sale terminals, or any other design which requires the processing capabilities of the Cortex M4.
Espen Krangnes is an AVR product marketing manager at Atmel Corporation, which he joined in 2004. He works on a variety of projects. Espen has a master of science degree in engineering cybernetics from the Norwegian University of Science and Technology. His master’s thesis involved using an Atmel AVR ATtiny26 to create a fully automated juvenile lobster larvae sorting machine.
Andreas Eieland is Senior Product Marketing Manager for Flash Microcontrollers at Atmel. Prior to this position, Mr. Eieland worked as an AVR Product Marketing Manager and Applications Engineer at Atmel's AVR Products Center. He holds a Master of Science degree from the Norwegian University of Science and Technology.
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