Large SoCs without an Ethernet interface typically have slow start-up times and high-power requirements — until now.
Atmel, a lead partner for the ARM Cortex-M7 processor launch in October 2014, has unveiled three new M7-based microcontrollers with a unique memory architecture and advanced connectivity features for the connected car market.
According to a company spokesman, E70, V71 and V70 chips are the industry’s highest performing Cortex-M microcontrollers with six-stage dual-issue pipeline delivering 1500 CoreMarks at 300MHz. Moreover, V70 and V71 microcontrollers are the only automotive-qualified ARM Cortex-M7 MCUs with Audio Video Bridging (AVB) over Ethernet and Media LB peripheral support.
Atmel is among the first suppliers to introduce the ARM Cortex-M7-based MCUs, whose core combines performance and simplicity and further pushes the performance envelope for embedded devices. The new MCU devices are aimed to take the connected car design to the next performance level with high-speed connectivity, high-density on-chip memory, and a solid ecosystem of design engineering tools.
Atmel’s Memory Play
Atmel has memory technology in its DNA, and that seems apparent in the design footprint of E70, V70 and V71 MCUs. The San Jose-based chipmaker is offering a flexible memory system that is optimized for performance, determinism and low latency.
Jacko Wilbrink, Senior Marketing Director at Atmel, said that the company’s Cortex-M7-based MCUs leverage Atmel’s advanced peripherals and flexible SRAM architecture for higher performance applications while keeping the Cortex-M class ease-of-use. He added that the large on-chip SRAM on SAM E70/V70/V71 chips is critical for connected car and IoT product designers since it allows them to run the multiple communication stacks and applications on the same MCU without adding external memory.
On-chip DMA and low-latency access SRAM architecture
Avoiding the external memories reduces the PCB footprint, lowers the BOM cost and eliminates the complexity of high-speed PCB design when pushing the performance to a maximum. Next, Tim Grai, another senior manager at Atmel, pointed out another critical take from Cortex-M7 designs: The tightly coupled memory (TCM) interface. It provides the low-latency memory that the processor can use without the unpredictability that is a feature of cache memories.
Grai says that the most vital memory feature is not the memory itself but how the TCM interface to the M7 is utilized. “The available RAM is configurable to be used as system RAM or tightly-coupled instruction and data memory to the core, where it provides deterministic zero-wait state access,” Grai added. “The arrangement of SRAM allows for multiple concurrent accesses.”
Cortex-M7 a DSP Winner
According to Will Strauss, President & Principal Analyst at Forward Concepts, ARM has had considerable success with its Cortex-M4 power-efficient 32-bit processor chip family. “However, realizing that it lacked the math ability to do more sophisticated DSP functions, ARM has introduced the Cortex-M7, its newest and most powerful member of the Cortex-M family.”
Strauss adds that the M7 provides 32-bit floating point DSP capability as well as faster execution times. With the greater clock speed, floating point and twice the DSP power of the M4, the M7 is even more attractive for applications requiring high-performance audio and even video accompanying traditional automotive and control applications.
Atmel’s Grai added an interesting dimension to the DSP story in Cortex-M7 processor fabric. He pointed out that true DSPs don’t do control and logical functions well and generally lack the breadth of peripherals available on MCUs. “The attraction of the M7 is that it does both—DSP functions and control functions—hence it can be classified as a digital signal controller (DSC).”
Grai quoted the example of Atmel V70 and V71 microcontrollers used to connect end-nodes like infotainment audio amplifiers to the emerging Ethernet AVB network. In an audio amplifier, you receive a specific audio format that has to be converted, filtered, modulated to match the requirement for each specific speaker in the car. So you need Ethernet and DSP capabilities at the same time.
Grai says that the audio amplifier in infotainment applications is a good example of DSC: a mix of MCU capabilities and peripherals plus DSP capability for audio processing. Atmel is targeting the V70 and V71 chips as a bridge between large application processors and Ethernet.
Most of the time, the main processor does not integrate Ethernet AVB, as the infotainment connectivity is based on Ethernet standard. Here, the V71 microcontroller brings this feature to the main processor. “Large SoCs, which usually don’t have Ethernet interface, have slow start-up time and high power requirements,” Grai said. “Atmel’s V7x MCUs allow fast network start-up and facilitate power moding.”
The SAM E70, V70 and V71
Atmel’s three new MCU devices are aimed at multiple aspects of in-vehicle infotainment connectivity and telematics control.
SAM E70: The microcontroller series features Dual CAN-FD, 10/100 Ethernet MAC with IEEE1588 real-time stamping, and AVB support. It’s aimed at automotive industry’s movement toward controller area network (CAN) message-based protocols holistically across the cabin, eliminating isolation and wire redundancy, and have them all bridged centrally with the CAN interface.
SAM V70: It’s designed for MediaLB connectivity and leverages advanced audio processing, multi-port memory architecture and Cortex-M7 DSP capabilities. For the media-oriented systems transport (MOST) architecture, old modules are not redesigned. So Atmel offers a MOST solution that is done over Media Local Bus (MediaLB) and is supported by the V70 series.
SAM V71: The MCU series ports a complete automotive Ethernet AVB stack for in-vehicle infotainment connectivity, audio amplifiers, telematics and head control units. It mirrors the SAM V70 series features as well as combines Ethernet-AVB and MediaLB connectivity stacks.
Majeed Ahmad is the author of books Smartphone: Mobile Revolution at the Crossroads of Communications, Computing and Consumer Electronics and The Next Web of 50 Billion Devices: Mobile Internet’s Past, Present and Future.
Atmel | Bits & Pieces 