Iot-based Smart Irrigation Systems: An

Figure 15. Most utilized temperature sensors.

	Min	Max
DHT11	0 ^◦C	50 ^◦C	±2 ◦C [28,59,61,62,64,71,87,93,94,101,103,115,117–119,121,130, 131,135,139,143,144,148,154,159,160,162]
DHT22	−40 ^◦C	125 ^◦C	±0.5 ^◦C [76,88,95,96,114,120,126,144,146,151,155,156,158]
LM35	−55 ^◦C	150 ^◦C	- [48,49,53,56,65,80,82,84,91,98,103,129,132,165]

Table 2. Temperature monitoring sensors.



_Sensor Temperature Range _{Accuracy Reference}

According to sensor type, thermistors such as the DHT11, the DHT22 and the AM2315 (Adafruit Industries, New York, NY, USA) are the most utilized type of temperature sensors, [14] (see Figure 16). The DHT11 and DHT22 are low-cost sensors. However, the AM2315 has a higher price with the advantages of a higher range (−40 ^◦C to 125 ^◦C) has higher accuracy (±0.1 ^◦C). Semiconductor-based integrated circuit temperature sensors like the LM35 (Texas Instruments, Dallas, TX, USA) and DS18B20 (Maxim Integrated, San Jose, CA, USA) [50], and band-gap proportional to absolute temperature sensors, SH10 (Sensirion AG, Staefa ZH, Switzerland) [35] and SH11 (Sensirion AG, Staefa ZH, Switzerland) [46], are the next most utilized temperature sensors by type. The SH10 and SH11 sensors provide both temperature and relative humidity readings. Furthermore, compared to the DHT11, they

present better temperature ranges and accuracy. They are however similar to the DHT22 in terms of temperature ranges, accuracy and price. The TMP36 (Analog Devices, Norwood, MA, USA) [34,152] is a temperature sensor comprised of a diode and the EE160 (SENSOVANT, Paterna, Spain) [75] is a resistive temperature detector sensor. The FM-KWS (Dongguan Holchan Electronics Technology Co., Ltd., Dongguan, China) [122] and the BME250 (Adafruit Industries, New York, NY, USA) [157] are of an unknown type.