Atmel ARM-based processors
Atmel ARM-based processors are microcontrollers and microprocessors integrated circuits, by Atmel, that are based on various 32-bit ARM processor cores, with Atmel-designed peripherals and tool support. Atmel ARM families complement their 8-bit AVR and 32-bit AVR32 lines of microcontrollers.
The "SAM" moniker in Atmel part numbers stands for "SMART Atmel microcontroller". The SMART brand includes application-specific ARM-based parts for Wi-Fi, such as the SmartConnect and Smart Direct lines, as well as ARM-based ICs meant for smart energy products such as gas and power meters. The SMART line is a key component of Atmel’s Internet of Things (IoT) strategy.
- 1 Overview
- 2 History
- 3 Products
- 4 Development tools
- 5 Documentation
- 6 See also
- 7 References
- 8 Further reading
- 9 External links
ARM licenses the core design for a series of 32-bit processors. ARM does not manufacture any complete silicon products, just intellectual property (IP). The ARM processors are RISC (reduced instruction set computing). This is similar to Atmel’s AVR 8-bit products, a later adoption of RISC architecture. Whereas the AVR architecture used Harvard architecture exclusively, some ARM cores are Harvard (Cortex-M3) and others are Von Neumann architecture (ARM7TDMI).
Semiconductor companies such as Atmel take the ARM cores, which use a consistent set of instructions and register naming, and add peripheral circuits such as ADCs (analog to digital converters), clock management, and serial communications such as USART, SPI, CAN, LIN, and I2C. Atmel made efforts to adapt advanced peripherals and power management that used very little power and can operate independently without having the CPU core powered up (sleepwalking). They also provided for DMA between external interfaces and memories increasing data throughput with minimal processor intervention.
Atmel sells both MCUs (microcontroller units) that have internal Flash memory, and MPUs (microprocessor units) that use external memory. In addition to the chips themselves, Atmel offers demo boards, both on its website, and through distribution channels such as Digi-key, Element14, Arrow, Avnet, Future Electronics, and Mouser.
Some of the "Atmel | SMART"-line of ARM-based products are meant for specific applications, such as their SAM4CP that is used in smart-grid energy meters. There are also Atmel wireless products built on ARM cores, such as the SmartConnect and Smart Direct wireless chips and modules.
- 1995 sign ARM ARM7TDMI "Thumb" core license agreement (ARMv4T Von Neumann architecture) (an MPU core Atmel made into MCU)
- AT91M40800 (1998)
- AT91FR40162 (2002)
- 1995 sign ARM920T/ARM9TDMI (MPU) core license agreement (ARMv4T Von Neumann architecture)
- AT91RM9200 (2003)
- 2000 sign ARM926EJ/ARM9E (MPU) core license agreement (ARMv5 architecture)
- AT91SAM9260 (2006)
- AT91SAM9263 (2007)
- SAM9XE (2008)
- SAM9R (2009)
- SAM9G (2009)
- SAM9M (2010)
- 2004 sign ARM1176JZ-S core license agreement (not used in Atmel parts)
- 2008 sign Cortex license agreement with ARM Holdings.
- Cortex-M3 (MCU) (ARMv7-M Harvard architecture)
- Cortex-M4 (MCU) (ARMv7E-M Harvard architecture)
- Cortex-A5 (MPU) (ARMv7-A architecture)
- Cortex-M0+ (MCU)in the SAM D20 (2013) (ARMv6-M architecture) – In June 2013, Atmel announced the SAMD20 series based on the ARM Cortex-M0+.
- Cortex-M7 (MCU) (ARMv7-M architecture)
- SAMS70 series, (2015) Atmel announced the SAM S70 series based on the ARM Cortex-M7. 
- SAME70 series, (2015) Atmel announced the SAM S70 series based on the ARM Cortex-M7. 
- SAME70 series, (2015) Atmel announced the SAM S70 series based on the ARM Cortex-M7, which is the first Atmel chip automotive grade with a Cortex-M7 core. 
The "Atmel | SMART"-branding is an umbrella for all AT91 ARM-based parts, even those without "AT91" in the name.
Microcontrollers have internal program memory as well as the conventional internal registers and RAM. Atmel ARM MCUs range from the SAM D10 series with as few as 14 pins, to the 144-pin SAM S70 and SAM E70 products.
The SAM4S, SAM4N, SAM3S, SAM3N, SAM7S (64-pin) families have pin-compatible IC footprints, except for USB device, though they are not voltage level compatible.
The SAM D family from Atmel consists of four different sub series (SAM D10, SAM D11, SAM D20, SAM D21). The devices are all based on the ARM Cortex-M0+ processor and offer different pin, memory, and feature combinations. The devices are pin- and code-compatible and share peripherals like the Event System and the SERCOM module. The Arduino Zero board uses a ATSAMD21G18 chip.
In 2009 Atmel announced the ATSAM3U line of flash-based microcontrollers based on the ARM Cortex-M3 processor, as a higher end evolution of the SAM7 microcontroller products. They have a top clock speed in the range of 100 MHz, and come in a variety of flash sizes. In the summer 2009 these parts were still sampling, and a development board had recently been made available.
In December 2009, the ATSAM3S line was announced. This features several enhancements for lower power operation and bill of materials cost reduction.
Market watchers observe that these Cortex-M3 products are competition for Atmel's own AVR32 UC3A products. Both are microcontrollers with largely identical peripherals and other hardware technology, flash-based, similar clock speeds, and with dense 16/32 bit RISC instruction sets.
- SAM3S – reduce power consumption
- SAM3U – high-speed USB
- SAM3X – the Arduino Due board uses the Atmel SAM3X8E microcontroller
- SAM4C – ARM Cortex-M4/M4F dual-core, which includes FPU
- SAM4E – ARM Cortex-M4F core, which includes FPU
- SAM4L – ARM Cortex-M4 core
- SAM4N – ARM Cortex-M4 core, pin-to-pin compatibility with SAM4S, SAM3S, SAM3N, SAM7S devices
- SAM4S – ARM Cortex-M4 core
- SAMG – ARM Cortex-M4F core, which includes FPU
These are based on the ARM Cortex-M7 core.
- SAMS70 – general purpose high performance MCU
- SAME70 – connectivity high performance MCU
- SAMV70, SAMV71 – automotive high performance MCU
There are a wide variety of AT91 flash-based microcontrollers, based on ARM7TDMI cores. These chips have a top clock speed in the range of 60 MHz, and come with a variety of flash sizes and peripheral sets.
- SAM7L – low power operation
- SAM7S – USB and other peripherals. SAM7S 64-pin chips are compatible with SAM4S, SAM4N SAM3S, SAM3N families.
- SAM7SE – USB, external memory support, and other peripherals
- SAM7X – Ethernet, USB, CAN, and other peripherals
- SAM7XC -–cryptographic extensions (notably AES support) to AT91SAM7X chips
The AT91SAM9XE flash-based microcontrollers are based on the ARM926ej-s cores. They have a top clock speed in the range of 200 up to 400 MHz, and come with a variety of flash sizes. They somewhat resemble flash-equipped AT91SAM9260 chips.
Atmel introduced the AT91SAM9 processors (using the ARM926ej-s core, with the ARMv5TEJ architecture) as its first broad market follow on to the highly successful AT91rm9200 processor. These processors improved on that predecessor by using less power, incorporating a newer and more powerful ARM core, and providing a variety of chips with different peripheral sets. While most are clocked at up to about 200 MHz, some can run at twice that speed. Processors include:
- SAM A5D2
- SAMA5D2 – 10/100 Ethernet, CAN, LCD, ClassD audio, QSPI, USB HSIC, Raw Bayer Image Sensor Interface, LPDDR3/LPDDR2/LPDDR/DDR2, up to 10 UART
- SAM A5D3
- SAMA5D31 – 10/100 Ethernet, LCD
- SAMA5D33 – Gigabit Ethernet, LCD
- SAMA5D34 – Gigabit Ethernet, LCD, dual CAN
- SAMA5D35 – no LCD, dual CAN, one Gigabit Ethernet + one 10/100 Ethernet
- SAMA5D36 – LCD, dual CAN, one Gigabit Ethernet + one 10/100 Ethernet
- SAM A5D4
- SAMA5D4 – 528 MHz (840 DMIPS), Neon, 128 KB L2 cache, video decoder, LCD, Ethernet
- Smart Direct
- SAM 4C/CM
- Arduino Due with 84 MHz Atmel ATSAM3X8E (ARM Cortex-M3 core).
- Arduino Zero with 48 MHz Atmel ATSAMD21G18 (ARM Cortex-M0+ core).
- Arduino MKR1000 with 48 MHz Atmel ATSAMW25 (ARM Cortex-M0+ core).
- Shield Compatible
- Xplained Pro
- SAM W21
Integrated development environments:
- Atmel - Studio 7
- IAR – Embedded Workbench for ARM
- Segger J-Link
The amount of documentation for all ARM chips is daunting, especially for newcomers. The documentation for microcontrollers from past decades would easily be inclusive in a single document, but as chips have evolved so has the documentation grown. The total documentation is especially hard to grasp for all ARM chips since it consists of documents from the IC manufacturer (for example, Atmel) and documents from CPU core vendor (ARM Holdings).
A typical top-down documentation tree is: manufacturer website, manufacturer marketing slides, manufacturer datasheet for the exact physical chip, manufacturer detailed reference manual that describes common peripherals and aspects of a physical chip family, ARM core generic user guide, ARM core technical reference manual, ARM architecture reference manual that describes the instruction set(s).
- Atmel ARM documentation tree (top to bottom)
- Atmel ARM-series website
- Atmel ARM-series marketing slides
- Atmel ARM-chip datasheet
- Atmel ARM-chip reference manual
- ARM core website
- ARM core generic user guide
- ARM core technical reference manual
- ARM architecture reference manual
Atmel has additional documents, such as: evaluation board user manuals, application notes, getting started guides, software library documents, errata, and more. See External Links section for links to official Atmel and ARM documents.
- ARM architecture, List of ARM microprocessor cores, ARM Cortex-M
- Microcontroller, List of common microcontrollers
- Embedded system, Single-board microcontroller
- Interrupt, Interrupt handler, Comparison of real-time operating systems
- JTAG, SWD
- Press Release; Atmel; February 4, 2013.
- Press Release; Atmel; June 1, 2009.
- Press Release; Atmel; December 15, 2009.
- Press Release; Atmel; November 9, 2010.
- Press Release; Atmel; February 28, 2012.
- Press Release; Atmel; October 26, 2011.
- Press Release; Atmel; September 24, 2012.
- Press Release; Atmel; January 14, 2013.
- Press Release; Atmel; August 12, 2014.
- Press Release; Atmel; January 7, 2014.
- Press Release; Atmel; January 5, 2015.
- Press Release; Atmel; October 1, 2014.
- Press Release; Atmel; September 14, 2015.
- Press Release; Atmel; June 17, 2013.
- Press Release; Atmel; July 15, 2015.
- Press Release; Atmel; Jan 6, 2015.
- Pin-compatible Cortex replacement for Atmel ARM7 SAM7S derivatives; ECE; May 2011.[permanent dead link]
- Microsite; Atmel; July 11, 2014.
- Arduino Zero; arduino.cc
- Arduino Due; arduino.cc
- SAM5A webpage; Atmel.com
- meta-atmel Yocto Compliant layer
- AT91SAM official documents
- ARM official documents