Autonomous peripheral operation
In computing, autonomous peripheral operation is a hardware feature found in some microcontroller architectures to off-load certain tasks into embedded autonomous peripherals in order to minimize latencies and improve throughput in hard real-time applications as well as to save energy in ultra-low-power designs.
Overview
Forms of autonomous peripherals in microcontrollers were first introduced in the 1990s. Allowing embedded peripherals to work independently of the CPU and even interact with each other in certain pre-configurable ways off-loads event-driven communication into the peripherals to help improve the real-time performance due to lower latency and allows for potentially higher data throughput due to the added parallelism. Since 2009, the scheme has been improved in newer implementations to continue functioning in sleep modes as well, thereby allowing the CPU (and other unaffected peripheral blocks) to remain dormant for longer periods of time in order to save energy. This is partially driven by the emerging IoT market.<ref name="R26"/>
Conceptually, autonomous peripheral operation can be seen as a generalization of and mixture between direct memory access (DMA) and hardware interrupts. Peripherals that issue event signals are called event generators or producers whereas target peripherals are called event users or consumers. In some implementations, peripherals can be configured to pre-process the incoming data and perform various peripheral-specific functions like comparing, windowing, filtering or averaging in hardware without having to pass the data through the CPU for processing.
Implementations
Known implementations include:
- Peripheral Event Controller (PEC) in Siemens/Infineon C166 and C167 16-bit microcontrollers since 1990<ref name="Wolf_1994"/><ref name="Siemens_2000_C167CR"/><ref name="Infineon_2004"/><ref name="Irber_2018"/>
- Intelligent autonomous peripherals (Capture compare unit CCU6) in Infineon XC800 series of 8051-compatible 8-bit microcontrollers since 2005<ref name="R24"/>
- Event System (EVSYS) in Atmel AVR XMEGA 8-bit microcontrollers since 2008<ref name="R12"/><ref name="R3"/>
- Peripheral Event System (PES) with SleepWalking<ref name="R1"/> in Atmel (now Microchip Technology) AVR32 AT32UC3L 32-bit microcontrollers since 2009<ref name="R10"/><ref name="R2"/><ref name="R17"/>
- Peripheral Reflex System (PRS) in Energy Micro (now Silicon Labs) Gecko EFM32 32-bit ARM-based microcontrollers since 2009<ref name="R11"/><ref name="R4"/><ref name="R17"/>
- IXYS/Zilog ZNEO Z16FMC 16-bit microcontrollers since 2011<ref name="R21"/><ref name="R22"/>
- Event Link Controller (ELC) in Renesas microcontrollers since 2011
- Programmable Peripheral Interconnect (PPI) in Nordic nRF 32-bit ARM-based microcontrollers since about 2011<ref name="R5"/>
- Autonomous peripherals in Infineon XMC 32-bit microcontrollers since 2012<ref name="R25"/>
- Data Transfer Manager (DTM) in Silicon Labs Precision32 SiM3L1 32-bit ARM Cortex-M3 microcontrollers since 2012<ref name="R15"/><ref name="R17"/><ref name="R19"/>
- Peripheral Event System (PES) with SleepWalking in Atmel (now Microchip Technology) SAM4L 32-bit ARM Cortex-M4 microcontrollers since 2012<ref name="R20"/>
- Power-Smart Peripherals in Freescale (now NXP) Kinetis L 32-bit ARM Cortex-M0+ microcontrollers since 2012<ref name="R23"/>
- Event System (EVSYS) with SleepWalking<ref name="R1"/> in Atmel (now Microchip Technology) SAMD, SAML and SAMC 32-bit ARM Cortex-M0+ microcontrollers since 2013<ref name="R6"/><ref name="R18"/>
- Core Independent Peripherals (CIP) in Microchip PIC16F<ref name="R7"/> and PIC18F<ref name="R8"/> as well as Microchip AVR ATtiny 8-bit microcontrollers since 2015<ref name="R9"/><ref name="R13"/><ref name="R14"/>
- Peripherals Interconnect Matrix in STMicroelectronics' STM32 32-bit ARM-based microcontrollers since 2015<ref name="R16"/>
- Low-Power Background Autonomous Mode (LPBAM) in STMicroelectronics' STM32U5 32-bit ARM-based microcontrollers since 2021<ref name="ST_2021"/>
See also
- Channel I/O
- Peripheral DMA controller (PDC)
- Clock gating, autonomous peripheral clock gating
- Power gating
- CPU power dissipation
- Low-power electronics
- Event-driven architecture
- Event-driven programming
- Always On, Always Connected (AOAC)
- Energy-Efficient Ethernet (EEE)
- TCP offload engine (TOE)
References
<references group="" responsive="1"><ref name="R1">Andersen, Michael P.; Culler, David Ethan (2014-08-25). "System Design Trade-Offs in a Next-Generation Embedded Wireless Platform" (PDF) (Technical Report). Electrical Engineering and Computer Sciences, University of California at Berkeley. No. UCB/EECS-2014-162. Archived (PDF) from the original on 2018-04-30. Retrieved 2018-04-30.</ref>
<ref name="R2">Eieland, Andreas; Krangnes, Espen (2012-10-28). "Improve Cortex M4 MCU interrupt responses with an intelligent Peripheral Event System". Atmel Corp. Archived from the original on 2018-04-30. Retrieved 2018-04-30.</ref>
<ref name="R3">Bjørnerud, Rune André (2009). "Event System Implementations for Microcontroller Circuits". NTNU Open (thesis). Institutt for elektronikk og telekommunikasjon. hdl:11250/2370969. Archived from the original on 2018-04-30. Retrieved 2018-04-29.</ref>
<ref name="R4">Bush, Steve (2009-10-21). "Energy Micro details its ARM Cortex M3-based EFM32G range". Electronics Weekly. Archived from the original on 2018-04-30. Retrieved 2018-04-29.</ref>
<ref name="R5">Elahi, Junaid; Rusten, Joar Olai; Olsen, Lasse; Sundell, Lars (2011-12-12). "Programmable peripheral interconnect". Nordic Semiconductor ASA. US patent US9087051B2. Retrieved 2018-04-29.</ref>
<ref name="R6">Riemenschneider, Frank (2013-06-18). "Mikrocontroller: Neue Cortex-M0+-Familie von Atmel" (in Deutsch). elektroniknet.de. Archived from the original on 2018-04-30. Retrieved 2018-04-29. {{cite web}}: Check |author-link= value (help)</ref>
<ref name="R7">Quinnell, Rich (2015-07-28). "8-bit Fights Back with Autonomous Peripherals". Santa Clara, USA: EETimes. Archived from the original on 2018-04-30. Retrieved 2018-04-30.</ref>
<ref name="R8">Bush, Steve (2016-10-31). "Autonomous peripherals for PIC18F MCUs". Electronics Weekly. Archived from the original on 2018-04-30. Retrieved 2018-04-29.</ref>
<ref name="R9">Stroh, Iris (2016-11-10). "Microchip Technology: 8-Bit-Offensive: AVR" (in Deutsch). elektroniknet.de. Archived from the original on 2018-04-30. Retrieved 2018-04-29.</ref>
<ref name="R10">Perlegos, Helen (2009-06-22). "Atmel Introduces AVR32 Microcontroller Which Lowers Industry's Best Power Consumption by 63%" (Press announcement). Atmel. Archived from the original on 2018-04-30. Retrieved 2018-04-30.</ref>
<ref name="R11">Bush, Steve (2009-07-08). "Energy Micro reveals more details on power efficient ARM MCU". Electronics Weekly. Archived from the original on 2018-04-30. Retrieved 2018-04-30.</ref>
<ref name="R12">Faure, Philippe (2008-02-26). "Atmel's AVR XMEGA Redefines System Performance for 8/16-bit Microcontrollers" (Press announcement). Atmel. Archived from the original on 2018-05-01. Retrieved 2018-05-01.</ref>
<ref name="R13">Di Jasio, Lucio (2015-05-05). "There is nothing left to be invented in embedded control, Part 1". Archived from the original on 2018-05-01. Retrieved 2018-05-01.</ref>
<ref name="R14">Di Jasio, Lucio (2015-05-12). "There is nothing left to be invented in embedded control, Part 2". Archived from the original on 2018-05-01. Retrieved 2018-05-01.</ref>
<ref name="R15">Manners, David (2012-10-03). "Lowest power 32-bit MCUs from Si Labs". Electronics Weekly. Archived from the original on 2018-05-02. Retrieved 2018-05-01.</ref>
<ref name="R16">"Peripherals interconnections on ST M32F405/7xx, STM32F415/7xx, STM32F42xxx, STM32F43xxx, STM32F446xx and STM32F469/479xx" (PDF) (Application note). STMicroelectronics. AN4640. Archived (PDF) from the original on 2018-05-01. Retrieved 2018-05-01.</ref>
<ref name="R17">"Raising Performance Without Breaking the Power Budget". Digikey. 2013-07-10. Archived from the original on 2018-05-02. Retrieved 2018-05-01.</ref>
<ref name="R18">"A closer look at Atmel's Peripheral Event System". Archived from the original on 2018-05-01. Retrieved 2018-05-01.</ref>
<ref name="R19">Silicon Laboratories. "Low Power Technology: Microcontroller Peripherals Push the Boundaries of Ultra-Low-Power". Archived from the original on 2018-05-01. Retrieved 2018-05-01. [1]</ref>
<ref name="R20">Kragnes, Espen; Eieland, Andreas (2012). "Redefining the Power Benchmark" (PDF) (White Paper). Atmel. Archived (PDF) from the original on 2018-05-01. Retrieved 2018-05-01.</ref>
<ref name="R21">"ZILOG Releases New 16-Bit MCU System On A Chip For Motor Control Applications". BusinessWire. 2011-01-06. Archived from the original on 2018-05-02. Retrieved 2018-05-01.</ref>
<ref name="R22">Coulson, Dave (2011-10-12). "The Need for Autonomous Peripheral Interoperation in Sensorless BLDC Applications". Convergence Promotions LLC. WP002003-0111. Archived from the original on 2018-05-01. Retrieved 2018-05-01. [2][3]</ref>
<ref name="R23">"Freescale Energy-Efficient Solutions: Kinetis L Series MCUs" (PDF) (White paper). Freescale. 2012. Archived (PDF) from the original on 2018-05-03. Retrieved 2018-05-03.</ref>
<ref name="R24">"XC800 Product Presentation - Capture Compare Unit CC6" (PDF). Infineon. May 2006. XC886 CC6 V1. Archived (PDF) from the original on 2018-05-10. Retrieved 2018-05-10. […] Drives need realtime performance – control loop must run faster than 2-4 PWM periods (e.g. 100-200us) – CPU performance is valuable and must be saved for key tasks – Question: How to offload the CPU? –Answer: Build intelligent and autonomous peripherals! […] CC6 in a Drive application: – generate PWM patterns for all kind of motors – operate always in a safe state – even in an error condition – interact with ADC for sensorless control of motors […] CC6 is used intensively – the more it works autonomous the more CPU load can be saved for control algorithms […]
</ref>
<ref name="R25">Bauer, Peter; Schäfer, Peter; Zizala, Stephan (2012-01-23). "One microcontroller platform. Countless solutions. XMC4000" (PDF) (Presentation). International Press Conference, Am Campeon, Munich, Germany: Infineon. Archived (PDF) from the original on 2018-05-10. Retrieved 2018-05-10.</ref>
<ref name="R26">Pitcher, Graham (2014-01-28). "Things worthy of consideration - The Internet of Things is pushing microcontroller developers to move in unexpected directions". New Electronics. pp. 22–23. Archived from the original on 2018-05-10. Retrieved 2018-05-10. [4]</ref>
<ref name="Wolf_1994">Wolf, Axel (March 1994). "Connecting the C166 architecture to CAN (I)" (PDF). Components. Applications Microcontrollers. Vol. XXIX, no. 4. Siemens Aktiengesellschaft. pp. 42–44. Archived (PDF) from the original on 2021-12-02. Retrieved 2021-12-02. (3 pages) (NB. Mentions the term "autonomous peripherals" in conjunction with the Siemens/Infineon SAB 80C166 in 1994 already. Part II of the article: [5])</ref>
<ref name="Infineon_2004">CAN Connecting C166 and C500 Microcontroller to CAN (PDF). 1.0. Infineon Technologies AG. February 2004. Application Note AP29000. Archived (PDF) from the original on 2020-10-22. Retrieved 2021-12-02. {{cite book}}: |work= ignored (help)</ref>
<ref name="Siemens_2000_C167CR">User's Manual - C167CR Derivatives - 16-Bit Single-Chip Microcontroller (PDF). 3.1 (2000-03 ed.). Munich, Germany: Infineon Technologies AG. March 2000 [2000-02, 1999-03, 1996-03, 1994-08, 1992-07]. Archived (PDF) from the original on 2020-10-27. Retrieved 2021-12-02. {{cite book}}: |work= ignored (help) (NB. Discusses an autonomously operating built-in CAN controller and a "Peripheral Event Controller" (PEC).)</ref>
<ref name="Irber_2018">Irber, Alfred (Summer 2018) [2016-02-25, 2009-09-25]. Embedded Systems SS2018 (PDF). 2.0 (in Deutsch). Munich, Germany: FH München - Hochschule für angewandte Wissenschaften, Fakultät für Elektrotechnik und Informationstechnik. pp. 1, 17, 28, 37–40. ES. Archived (PDF) from the original on 2021-12-02. Retrieved 2021-12-02.</ref>
