Nodes work mode. Because the plant growth does not require
very strict real-time monitoring, in order to reduce the energy consumption of sensor nodes to prolong the network lifetime, sleep mode was designed on these nodes. Working in this mode, the sensor nodes are asleep and waiting for the timer to overflow, which will generate the interrupt signal to wake up
the nodes, as shown in Figure 2. The sleep time of the node Tsleep is set at the requirement of the monitoring performance. In our implementation, we set Tsleep=600 s. We also set active time of the node Tactive=30 s or Tactive=60 s, respectively.