Smart Agriculture can sometimes live in the most unexpected places, such as a cow’s rumen in the case of the smaXtec, a health monitoring system from an Austrian company of the same name that decided to use an STM32L431KC microcontroller (MCU) and our LIS2DW12 three-axis MEMS accelerometer. The rumen is the first chamber of the cow’s alimentary canal, meaning it mixes and starts digesting food. It is also the best place to insert a bolus, a capsule fed to the cow that sits in the rumen. smaXtec is a bolus that’s small (105 mm x 35 mm), and that keeps track of the bovine’s critical physiological data, such as pH, activity levels, and temperature. Beyond the ability to track the animal’s well-being, it can determine when the cow is in heat, therefore significantly increasing the chances of fertilizing it.
Artificial insemination enabled farmers to realize substantial savings compared to natural service, as it removed the costs of breeding and caring for a bull. According to the Canadian Beef Cattle Research Council, artificial insemination has a “net benefit of $11,110 for a 40-cow herd”. However, the topic is still the subject of many scientific debates trying to find the techniques that will yield the best results. The College of Agricultural Sciences at the Pennsylvania State University estimates that technicians who recently received training have an average breeding rate of about 70 %. Hence, there is clearly room for improvement, especially as the prices for bull semen continue to increase.
From Outside to Inside the Cow, The New smaXtec Approach
Determining when a cow is in heat is hard. According to PennState, between 7 % and 20 % of cows are not in heat when they undergo insemination. Additionally, farmers must determine when the estrus started because they must perform the artificial insemination near the end of the “standing heat” phase. At this stage, the animal shows signs that it’s ready for mounting by a male counterpart, which indicates that ovulation should occur in about 12 hours.
The process thus demands a reasonably accurate reading of the animal, but aside from a visual analysis, farmers have limited tools, which makes the smaXtec even more attractive. Moreover, the fact that they use a bolus means that they can get more information than competing solutions that just track activity. For instance, the interface can inform farmers about the animal’s drinking behavior and its rumen’s pH, or announce the birth of a calf about 15 to 20 hours before it happens.
To be practical, the smaXtec needs to last four years on a single battery because it is the typical timeframe in which a dairy cow is productive. The Austrian company was thus pushing to save energy, which led its teams to use the LIS2DW12, our accelerometer with an active low-power mode of just 1 µA. With its output data rate oscillating between 1.6 Hz and 1.6 kHz, the device offers the accuracy necessary to precisely determine if it is restless and nervous, some of the first symptoms of estrus, without draining the battery too much or necessitating a larger PCB. Indeed, the LIS2DW12 is available in a small thin LGA (Land Grid Array) package, helping the smaXtec keep the overall design small to make it easy to swallow, thus preventing any discomfort or pain to the animal.
Knowing the Cow Inside Out, The Journey From the STM32L4 to Cloud
smaXtec also chose our STM32L431KC microcontroller because it offered an interesting power-to-performance ratio. As the company explained, they are looking into developing pre-processing algorithms to limit the amount of data the system needs to send to the cloud by locally computing some of the information from the sensors. The other reason behind their choice of MCU was our 10-year longevity program, which was the best out of all the manufacturers they were considering during the prototyping phase. The fact that we stand by our products for such a long time gave them the peace of mind they needed. Too often, engineers overlook the longevity of a manufacturer’s support to focus more on technical specifications, but smart agriculture needs components that farmers and manufacturers can rely on for a very long time.
Moreover, smaXtec also used our Nucleo boards to test some of our MCUs, evaluate the ease-of-use of our platform, and experiment with some of our code. These were important factors that would determine how fast their teams would be able to bring their health monitoring system to market. To facilitate developments, the company used our STM32CubeL4, a software package that contains Hardware Abstraction Layers and low-level APIs that ensure developers can jumpstart their application on our MCU. smaXtec even used our I-CUBE-LRWAN expansion pack to create the sub-gigahertz application that transmits data from the bolus to a gateway that relay information to a cloud platform.
