Single Chip MCU + DSP Architecture for Automotive: SAMV71

Single Chip MCU + DSP Architecture for Automotive: SAMV71
by Eric Esteve on 04-29-2015 at 7:00 pm

It’s all about Cost of Ownership (CoO) and system level integration. If you target automotive related application, like audio or video processing or control of systems (Motor control, Inverter…) you need to integrate strong performance capable MCU with a DSP. In fact if you expect your system to support Audio Video Bridging (AVB) MAC on top of the targeted application and to get the automotive qualification, ARM Cortex-M7 processor based Atmel SAMV70/71 should be your selection: offering the fastest clock speed of his kind (300 MHz), integrating a DSP Floating Point Unit (FPU), supporting AVB and qualified for automotive.

Let’s have a closer look at the SAMV71 internal architecture:

When developing a system around a Micro Controller Unit (MCU) you expect this single chip to support as many peripherals as needed in your application to minimize the global cost of ownership. That’s why you can see the long list of system peripherals (top left of the block diagram).
Atmel SAMV71 is dedicated to support automotive infotainment application, so the Dual CAN and Ethernet MAC support (bottom right). If we dig into these functions, we can list these supported features:

  • 10/100 Mbps, IEEE1588 support
  • MII (144-pin), RMII (64-, 100, 144-pin)
  • 12 KB SRAM plus DMA
  • AVB support with Qav & Qas HW support for Audio traffic support
  • 802.3az Energy efficiency support
  • Dual CAN-FD
  • Up to 64 SRAM-based Mailboxes
  • Wake up from Sleep or Wake up Modes on RX/TX

The automotive-qualified SAM V70 and V71 series also offer high-speed USB with integrated PHY and Media LB, which, when combined with the Cortex-M7 DSP extensions, make the series ideal for infotainment connectivity and audio applications. Let’s take a look at this DSP benchmark:

If you are not limited by budget consideration and can afford integrating one standard DSP along with a MCU, you will probably select the SHARC 21489 DSP (from Analog devices) offering the best-in-class benchmark results for FIR, Biquad and real FFT. But such performance has a cost, not only a $ cost but also in term of power consumption and board footprint, let’s call it “cost of ownership”. Automotive applications are running in production by million units per year, and $ cost is absolutely crucial in this market segment and you will quickly decide to go to an integrated solution.

To support audio or video infotainment application, you expect the DSP integrated in the Cortex M7 to be “good enough” and you can see from this benchmark results that it’s the case for Biquad for example, as ARM CM7 is equal or better than any other DSP (TI C28, Blackfin 50x or 70x) except the SHARC 21489… but much cheaper! Good enough means that the SAMV70 will support automotive audio (Biquad in this case) and keep enough DSP power for Ethernet MAC (10/100 Mbps, IEEE1588) support.

You can see on the above picture the logical SAMV71 architectures for Ethernet AVB support and how using the DSP capabilities for Telematics Control Unit (TCU) or Audio Amplifier.

Integrating a DSP means that you need to develop the related DSP code. Because the DSP is tightly integrated into the ARM CM7 core, you may use the MCU development tools (and not specific DSP tools) for developing your code. Since February the ATSAMV71-XULT (Full featured Xplained board) is available from Atmel. As this board has been built around the features rich SAMV71, you can develop your automotive application on exactly the same MCU architecture than the part going into production:

More information about this evaluation/development board is available on Atmel web here.

From Eric Esteve from IPNEST