# Autonomous Active Tag Using Energy Harvesting Strategies
## 2 Materials and Methods
### Processing Module  
The processing module has four submodules: the microcontroller, the memory, the transceiver and the antenna, as can be seen above in Figure 1. Each one will be described in its own subsection. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Information about the Authors of the Study** & \
\begin{tabular}{c} **Energy Harvesting** \\ **Method** \\ \end{tabular} &
\begin{tabular}{c} **Energy Storage** \\ **Method** \\ \end{tabular} & **Application** \\ \hline [PERSON] and [PERSON] [5] & Fuel cell & - & - \\ [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON], and [PERSON] [6] & Bio cell & Supercapacitor & - \\ [PERSON]; [PERSON]; [PERSON], and [PERSON] [7] & Radio Frequency technique & Supercapacitor & Food monitoring \\ [PERSON] et al. [8] & Radio Frequency technique & Supercapacitor & Monitoring temperature \\ [PERSON]; [PERSON], and [PERSON] [9] & Thermal technique & Battery & Bracelet as a wearable \\ [PERSON] et al. [10] & Mechanical technique & - & Electronic devices as a calculator or LEDs \\ [PERSON]; [PERSON]; [PERSON]; [PERSON], and [PERSON] [11] & Solar technique & Battery & Extend the life of wireless sensor networks \\ [PERSON]; [PERSON]; [PERSON]; [PERSON]; and [PERSON] [12] & Solar technique & Battery & For satellite \\ [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON], and [PERSON] [13] & Solar technique & Supercapacitor & Animal monitoring \\ [PERSON]; [PERSON] A.; [PERSON]; [PERSON], and [PERSON] [14] & Solar and wind-based techniques & - & To meet the demand of remote sensors and small-scale portable electronics; \\ [PERSON]; [PERSON]; [PERSON]; [PERSON], and [PERSON] [15] & Solar technique and Radio Frequency technique & Battery or & To supply wireless sensor networks \\ [PERSON] [PERSON]; [PERSON]; [PERSON]; [PERSON] [PERSON] and [PERSON] [16] & Radio Frequency, thermal, and photovoltaic or & Battery or & Feed wireless sensor networks \\ This study & vibrational techniques & supercapacitor & Road Maintenance \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Current methods of energy harvesting techniques and their applications. Figure 1: Autonomous active tag architecture. Normal operation: energy is obtained from solar and mechanical harvest submodules, which is stored in a supercapacitor and regulated to feed the diverse elements of the processing module. This is indicated by simple arrows. Bold lines reflect the communication of data between submodules. Dotted lines show the elements oriented to debugging the device. The double dotted line between storage and battery means that the battery is connected to the storage submodule. The main function of this module is the control over the tag operation, which includes the tasks of transmitting, receiving and saving data. All these tasks use different strategies to provide full functionality with the minimum power consumption. These techniques are based on programming the low power consumption modes of the microcontroller and the transceiver, as well as synchronizing them in conjunction with the memory EEPROM (Electrically Erasable Programmable Read-Only Memory), for a correct running. In this case, the effort to achieve the best performance is important because it will lead to a greater lifetime of the device. The first technique is the use of a low working voltage, as low voltages usually imply less consumption and a longer lifetime. In this case, the lowest voltage that components allow is 1.8 volts. The second design decision is to select the components of the tag with less current consumption among those that fit in the other features. The third is to work in the 868 MHz Europe license-free band, which has a lower power consumption and simplified protocols. The upper one of 2.4 GHz is a more frequently used band than the 868 MHz band, so it has more interferences. In the case of the lower license-free band of 433 MHz, the 868 MHz band has a better compromise between communication range and binary rate. The workflow of this module can be separated in two directions.