Eric Esteve explains why the latest Cortex-M7 MCU series will open up countless capabilities for drones other than just flying.
By nature, avionics is a mature market requiring the use of validated system solution: safety is an absolute requirement, while innovative systems require a stringent qualification phase. That’s why the very fast adoption of drones as an alternative solution for human piloted planes is impressive. It took 10 or so years for drones to become widely developed and employed for various applications, ranging from war to entertainment, with prices spanning a hundreds of dollars to several hundreds of thousands. But, even if we consider consumer-oriented, inexpensive drones, the required processing capabilities not only call for high performance but versatile MCU as well, capable of managing its built-in gyroscope, accelerator, geomagnetic sensor, GPS, rotational station, four to six-axis control, optical flow and so on.
When I was designing for avionics, namely the electronic CFM56 motor control (this reactor being jointly developed by GE in the U.S. and Snecma in France, equipping Boeing and Airbus planes), the CPU was a multi-hundred dollar Motorola 68020, leading to a $20 per MIPS cost! While I may not know the Atmel | SMART SAM E70 price precisely — I would guess that it cost a few dollars — what I do I know is that the MCU is offering an excess of 600 DMIPS. Aside from its high performance, this series boasts a rather large on-chip memory size of up to 384KB SRAM and 2MB Flash — just one of many pivotal reasons that this MCU has been selected to support the “drone with integrated navigation control to avoid obstacle and improve stability.”
In fact, the key design requirements for this application were: +600 DMIPS, camera sensor interface, dual ADC and PWM for motor control and dual CAN, all bundled up in a small package. Looking at the block diagram below helps link the MCU features with the various application capabilities: gyroscope (SPI), accelerator (SPI x2), geomagnetic sensor (I2C x2), GPS (UART), one or two-channel rotational station (UART x2), four or six-axis control communication (CAN x2), voltage/current (ADC), analog sensor (ADC), optical flow sensor (through image sensor Interface or ISI) and pulse width modulation (PWM x8) to support the rotational station and four or six-axis speed PWM control.
For those of you who may not know, the SAM E70 is based on the ARM-Cortex M7 — a principle and multi-verse handling MCU that combines superior performance with extensive peripheral sets supporting multi-threaded processes. It’s this multi-thread support that will surely open up countless capabilities for drones other than simply flying.
Today’s drones already possess the ability to soar through the air or stay stationary, snapping pictures or capturing HD footage. That’s already very impressive to see sub-kilogram devices offering such capabilities! However, the drone market is already looking ahead, preparing for the future, with the desire to get more application stacks into the UAVs so they can take in automation, routing, cloud connectivity (when available), 4G/5G, and other wireless functionalities to enhance data pulling and posting.
For instance, imagine a small town tallying a few thousand habitants, except a couple of days or weeks per year because of a special event or holiday, a hundred thousand people come storming into the area. These folks want to feed their smartphone with multimedia or share live experiences by sending movies or photos, most of them at the same time. The 4G/5G and cloud infrastructure is not tailored for such an amount of people, so the communication system may break. Yet, this problem could be fixed by simply calling in drone backup to reinforce the communication infrastructure for that period of time.
While this may be just one example of what could be achieved with the advanced usage of drones, each of the innovative applications will be characterized by a common set of requirements: high processing performance, large SRAM and flash memory capability, and extensive peripheral sets supporting multi-threaded processes. In this case, the Cortex M7 ARM-based SAM E70 MCU is an ideal choice with processing power in excess of 640 DMIPS, large on-chip SRAM (up to 384 KB) and Flash (up to 2MB) capabilities managing all sorts of sensors, navigation, automation, servos, motor, routing, adjustments, video/audio and more.
Intrigued? You’ll want to check out some of the products and design kits below:
This post has been republished with permission from SemiWiki.com, where Eric Esteve is a principle blogger as well as one of the four founding members of SemiWiki.com. This blog first appeared on SemiWiki on July 18, 2015.