How to use 8-bit MCU to realize smart farm technology

Technological advances have both advantages and disadvantages for modern farms. Modern agricultural and horticultural techniques allow more crops to be produced on a smaller area to meet the needs of a growing population . However, the quality of fresh food produced on farms today is declining, and the quantity is still not enough for farmers to remain profitable.

Agriculture itself is very unstable. The reason is that the annual output is greatly affected by the external environment. In order to meet the demand for greater consistency and sustainability in agriculture, another modern technology needs to be applied to agriculture (Figure 1). Let's first learn about smart farms.

Figure 1. Farmers can remotely monitor the health of their crops and livestock, providing valuable information to ensure consistent farming practices.

Powerful connected livestock monitoring systems help increase the number of healthy animals, thereby improving food quality. Soil and plant health monitoring systems allow farmers to monitor the health of their crops at an unprecedented level of detail. With today's embedded connected sensor systems, the "smart farm" of the future will have the tools and capabilities needed to increase yields and profits, while still meeting the quality expectations of discerning customers.

The information collected by these sensors can help guide farmers to make the best decisions for their farms, thereby increasing crop and livestock productivity while reducing the use of water, pesticides and fertilizers. This not only helps to reduce the impact of farms on the natural environment, but also improves the quality of the land and ensures sustainable development for future generations.

Key enabler of embedded and wireless technologies

Simply put, the main solution to ensure the sustainability of modern farms is to provide useful information to farmers. Thanks to today's innovations in embedded and wireless technologies, this can be achieved by using a large array of low-cost networked sensors. These sensors typically monitor various on-site conditions of farmland or livestock, including temperature, pH, humidity, activity data, and GPS coordinates. Next, these sensors transmit the above data to a centralized database, usually cloud-based, through wireless communication networks such as 4G/5G cellular and LoRa.

This data can then be accessed online from any internet-connected device and quickly analyzed to determine if corrective action is needed, allowing farmers to access analytics on their farm from anywhere in the world.

The concept of connected sensor nodes is not new; however, to ensure adequate performance and reliability in this unique and harsh environment, several key requirements must be met. First, a reliable power source is required, a challenge that is difficult to address because farms are generally not equipped with 1,000-foot extension cords.

The nodes need to be battery powered and energy efficient enough to operate for months or even years without battery replacement. To meet this challenge, microcontroller (MCU) based systems are needed to achieve extremely high system efficiency, manage complex tasks with low core CPU utilization, and not lose power when the system is not working.

Secondly, sensor nodes in smart farms need to remain operational in harsh remote areas and even be mounted on animals. For the entire system, practical and innovative solutions are needed to ensure stability and functionality. Nodes need to remain on site for a long time and require minimal hardware maintenance. All software updates need to be done remotely and securely. To meet this demand, reliable remote connectivity needs to be provided on the farm site through the most common wide area network (WAN) infrastructure.

When designing connected systems for smart farm applications, engineers must take into account the diversity of plants and animals being monitored. Plant health monitoring systems can measure a variety of environmental conditions, including water levels, soil conditions, pH, and light levels, while livestock tracking systems need to include GPS coordinates, gait monitors, pulse oximeters, and other sensors that monitor key health data points.

In either case, the ideal commercial solution is a universal base node design that can be purchased directly to meet the needs of individual farms. To achieve this goal, the base node must be flexible enough to interface with a variety of analog and digital sensors.

However, there is another, more difficult design challenge that involves the various engineering disciplines that need to be applied in such systems. For smart farm component designers or engineering teams, in addition to being proficient in cloud infrastructure, they also need expert experience in traditional embedded design techniques, RF communications (including the full details of LoRa, Wi-Fi, and cellular topologies), and cybersecurity.

8-bit MCUs debut

To expand the infrastructure of smart farms, we must first start from the aspects that are not considered when exploring cutting-edge applications. Since most sensor nodes in smart farms are battery-powered, remotely located, and require occasional maintenance, the world's most energy-efficient microcontrollers are required to achieve the best control solutions.

8-bit MCUs have a history of more than 50 years, and while they have been the choice for most low-power embedded tasks, the latest devices have added many modern features that directly meet the needs of smart agriculture and horticultural systems. Among the many new features, the Core Independent Peripherals (CIPs) on PIC® and AVR® microcontrollers are "enhancers" of embedded designs.

CIPs can work independently of the chip's CPU, so designers can set them up to handle common, repetitive tasks in the lowest power mode. CIPs also offer another benefit in low-maintenance environments, helping designers improve system reliability. Because CIPs can be programmed to act like a tiny FPGA in an MCU, they can effectively avoid software deviations such as stack overflow or underflow.

Interfacing with a variety of digital and analog sensors using the same networking base node controller can be challenging. Fortunately, there are modern MCUs that meet the needs of these specialized applications while minimizing external components. Such MCUs offer SPI and I2C interfaces for digital sensor connectivity, as well as differential analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) with programmable gain amplifiers (PGAs) for extreme sensor flexibility (Figure 2). These features give designers the freedom to build highly customizable, modular sensor nodes for smart farm applications.

Figure 2. Small, efficient MCUs are key to ensuring sustainable development of smart agriculture

As MCU architectures modernize, their supporting development hardware and software environments are also maturing. For engineering teams at small companies where embedded systems, RF antenna design, and cloud connectivity are not core competencies, rapid prototyping boards are the panacea. Prototyping boards provide designers with simple reference examples and even include GitHub repositories and firmware that can connect to the most common cloud providers.

Remote sensor technology

Today’s agriculture and horticulture are undergoing a technological revolution. Real-time access to plant and animal health data via the internet is transforming the way farms operate, resulting in higher yields and greater vitality of the land (Figure 3).

Figure 3. Remote sensor technology using 8-bit MCUs can monitor farm health and ensure crops receive the necessary care to thrive.

The forefront of this revolution is “available everywhere” cloud connectivity, but the foundation is still built using mature 8-bit microcontrollers. Modern MCU architectures such as AVR and PIC with CIP will be key components in bridging the gap between sensors and the cloud for developers of sustainability-enhanced products, both now and in the future.