# Towards a Low-Cost Precision Viticulture System Using Internet of Things Devices
## 5 Hardware Infrastructure
### Radio Unit  
The proper selection of the wireless communication technology that will be used to transfer data between the nodes and the control room in crucial. It is important that the selected technology has low power requirement so the total energy consumption in each node is low. In terms of transmission range, a long transmission range would be more applicable for a viticulture application. The packets usually  
Figure 8: Arduino MKR 1300 [28]. \begin{table}
\begin{tabular}{l r} \hline \hline Microcontroller & SAMD21 Cortex-M0+ 32 bit low power ARM MCU \\ \hline Power Supply & 5 V \\ \hline Digital I/O Pins & 8 \\ \hline Analog Input Pins & 7 \\ \hline Length \(\times\) Width & 67.64 mm \(\times\) 25 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 3: MKR 1300 Specification. Figure 7: Soil temperature (**a**) sensor and (**b**) experimental data readings. need to travel from remote areas to a control room, hence, a long transmission range would minimize the number of hops and relay nodes that would be necessary between the nodes and the control room. At the same time, for the proposed application, the data size will be low. Only small packets will be sent from the different nodes to the control room every couple of minutes, hence real-time data transmission is not a requirement for such application. Among the available wireless technologies, Wi-Fi (2.4 GHz), Bluetooth Low Energy (BLE) and LoRaWAN are popular for many applications. The characteristics of each technology are shown in Table 4.  
The three wireless protocols were tested and evaluated mainly based on power consumption. To experiment with Wi-Fi and Bluetooth, the Arduino MKR 1010 microcontroller was used [29]. This contains a U-BLOX NINA-W102 chip, which is capable of 2.4 GHz operation, capable of Wi-Fi and BLE [29]. For the LoRaWAN experiments, Arduino MKR 1300 was used, since it is designed to use the LoRa protocol with an integrated Murata CMWX1 ZZABZ chip [28]. The frequencies available on this chip are 433 MHz, 868 MHz, and 915 MHz. The processor of each microcontroller is an Atmel ATSAMD21 ARM-based microprocessor. The consistency of this microprocessor and other peripherals on the boards keep the small variances between each prototype negligible. A summary of each configuration of the prototype can be seen in Table 5.  
To examine the appropriateness of each wireless technology for the proposed system, the focus was on the energy requirements. Three MKR boards were used, one for each technology and one soil moisture and one soil temperature sensor in each board was connected. Each node transmitted data reported from the sensor every second, without any filtering and processing, for approximately 5 min. All the prototypes were powered using the Monsoon power monitor in order to be able to monitor the energy requirements. The Monsoon power monitor is able to get very accurate measurement readings and allows the user to easily log data to average the power over an amount of time [30]. The results are shown in Figure 9. The energy consumption of each board when the two sensors are connected on the board was measured, shown in Figure 9a. As expected, the energy consumption of the \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Technology** & **Transmission Range (m)** & **Bitrate (Mbit/s)** & **Power Requirements** & **Advantages** & **Disadvantages** \\ \hline
**Wi-Fi** & up to 100 & 288.8 & Moderate & High availability, does not require extra hardware & Prone to noise, high energy consumption \\ \hline
**BLE v4** & up to 60 & 25 & Low & Low energy consumption & Prone to interference \\ \hline
**LoRaWAN** & up to 15000 & 0.05 & Extremely Low & Very long transmission range, low energy consumption & Requires extra hardware \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of wireless technology characteristics.