How 8-bit MCUs enable smart farm technology

The modern farm has been both blessed and cursed by the advancement of technology. Modern agricultural and horticultural techniques have enabled higher crop yields with smaller footprints supporting ever-growing populations. However, the quality of today’s farm fresh food has been deteriorating, while the quantity is still not enough to keep farmers profitable.

The agriculture industry is inherently unstable. This is largely due to the impact of external environmental circumstances on yield from year to year. The desire for more consistency and sustainability in agriculture is driving the adoption of another kind of modern technology in this industry (Figure 1). Enter the smart farm.

Figure 1 Farmers can remotely monitor crops and livestock health, providing valuable information that ensures consistency in the agricultural industry. Source: Microchip

The availability of networked livestock monitoring systems has increased the number of healthy animals, leading to improved quality of food. Soil and plant health monitors provide farmers with the ability to monitor crop health to levels of detail not previously possible. Thanks to today’s embedded networked sensor systems, the “smart farm” of the future will have the tools and capabilities needed to increase yield and profitability while still supporting the quality levels required by discerning customers.

The information that is gathered from these sensors can help guide farmers in making the best decisions for their farms, allowing them to nurture crops and livestock to higher productivity levels while decreasing the use of water, pesticides, and fertilizer. This can help reduce the farm’s impact on its natural environment and improve the quality of the land; thus, ensuring sustainability for generations to come.

Embedded and wireless key enablers

Simply put, the principal solution for ensuring sustainability in the modern farm is to supply usable information to farmers. Due to the innovation of today’s embedded and wireless technologies, this objective can be achieved by implementing massive arrays of low-cost networked sensors. These sensors will typically monitor on-location conditions—temperature, pH, moisture, activity data and GPS coordinates—from farmland or livestock. Next, these sensors will transmit this data via wireless communication networks such as 4G/5G cellular and LoRa to a centralized and typically cloud-based database.

The data can then be accessed online by any Internet-connected device, and quickly analyzed to determine if corrective actions are needed. This allows a farmer to access the farm’s analytics from anywhere in the world.

Networked sensor nodes are not a new concept; but to ensure a level of performance and reliability in this uniquely difficult space, some key requirements must be met. First, they need a reliable power source, which is a challenging situation to resolve since a farm does not come with 1,000-foot extension cords.

Nodes would need to be battery-powered and efficient enough to last months or even years without battery replacement. This challenge requires high system efficiency which is typically achieved by implementing a microcontroller (MCU)-based system that can manage various complex tasks without heavy core CPU usage and power down when the system is inactive.

Second, sensor nodes on the smart farm need to remain operable in harsh, remote areas and perhaps even be attached to animals. The entire system is exposed to the elements which requires practical but innovative solutions to ensure robustness and functionality. Nodes would need to remain in the field for long periods of time and require very little hardware service. All software updates need to be completed remotely and securely. This requires reliable remote connectivity via the most common wide area networking (WAN) infrastructure at the farm’s locale.

When designing networked systems destined for smart farm applications, engineers must anticipate an incredibly wide variety of plants and animals being monitored. Plant health monitoring systems may measure various environmental conditions—including water levels, soil conditions, pH levels and light levels—while livestock trackers may incorporate GPS coordinates, gait monitors, pulse oximeters, and other sensors that monitor key health data points.

In either case, an ideal commercial solution would be a common base node design that can be easily adapted to the needs of the individual farm at the time of purchase. To achieve this, the base node must be flexible enough to interface with a wide variety of analog and digital sensors.

Another, more difficult design challenge concerns the wide variety of engineering disciplines needed to implement in such a system. Smart farm component designers or engineering teams need to have expert-level experience in classical embedded design techniques, RF communication—including the ins-and-outs of LoRa, Wi-Fi, and cellular topology—and network security in addition to being well-versed in cloud infrastructure.

Enter 8-bit MCUs

The path to scaling smart farm infrastructure starts in a place that isn’t commonly thought of when discussing cutting-edge applications. Since the vast majority of sensor nodes on the smart farm are battery powered, remotely located and sporadically maintained, the optimal control solution must involve the most power-efficient microcontrollers on the planet.

The 8-bit MCUs have been with us for 50 years, and while they have always been the lowest-power option for most embedded tasks, the newest devices have been modernized to directly address the needs of smart agricultural and horticultural systems. Among the many new features, the core independent peripherals (CIPs) available on PIC and AVR microcontrollers are a “force multiplier” for embedded design.

CIPs can act independently from the chip’s CPU, which allows designers to set them up to handle common and repetitive tasks with the lowest amount of power consumed. An additional benefit that CIPs provide in low-maintenance environments is their ability to help designers increase system reliability. Since CIPs are programmed as though they were tiny FPGAs included with the MCU, they are effectively immune to software excursions such as stack overflows or underflows.

Interfacing with a wide variety of digital and analog sensors using the same Internet-connected base node controller can be a challenge. Fortunately, there are modern MCUs that are designed for this very application while minimizing external componentry. Such MCUs offer SPI and I2C interfaces for digital sensor connectivity as well as differential analog-to-digital converter (ADC) with programmable gain amplifier (PGA) and digital-to-analog converter (DAC) for a high level of sensor flexibility (Figure 2). This gives designers the freedom to build highly customizable and modular sensor nodes for smart farm applications.

Figure 2 Small, efficient MCUs are key to sustainability in smart farming. Source: Microchip

Alongside the modernization of MCU architectures, their accompanying development hardware and software environments have also come a long way. For engineering teams at small companies where embedded systems, RF antenna design and cloud connectivity are not all core competencies, rapid prototyping boards are life savers. This provides designers with an easy example to follow and even includes a GitHub repository with firmware to connect with popular cloud providers.

Remote sensor technology

Today’s agriculture and horticulture industries are undergoing a technological revolution. Access to plant and animal health data via the Internet in real-time is transforming the way farms are run, with a result of ever-higher yields and increased land viability (Figure 3).

Figure 3 The 8-bit MCU-enabled remote sensor technology to monitor farm health ensures that crops receive the necessary care to thrive. Source: Microchip

At the forefront of this revolution is “available anywhere” cloud connectivity, but its foundation will continue to be built with the venerable 8-bit microcontroller. Modern MCU architectures, such as AVR and PIC with CIPs, will be key components to bridge the gap between sensor and cloud for developers of sustainability-enhancing products—now and into the future.

Grace San Giacomo is an engineer at Microchip Technology’s 8-bit microcontroller business unit.

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