Hydro Probe Click Board™

Product Code: MIKROE-4131

How Does The Hydro Probe Click Board™ Work? The Hydro Probe Click Board™ uses the capacitive soil moisture sensor based on capacitive changes that are used to detect the volumetric water content of the soil. It based its operation on capacitive measurement, which has a great advantage over resistive measurement. Compared with resistive soil moisture sensors, capacitive sensors do not require direct exposure of the metal electrodes, which can significantly reduce the erosion of the electrodes. The Hydro Probe Click Board™ can only qualitatively test the humidity of the soil and can't measure quantitatively. When the humidity of the soil rises, the value of the output decreases; conversely, when the humidity decreases, the output value becomes higher. It operates with a flexible power supply voltage range which makes it suitable for 3.3V and 5V MCUs. The Hydro Probe Click Board™ performs its function as capacitive soil moisture sensor by using two main components, CMOS RC oscillator MIC1557 and 12-bit A/D converter MCP3221 with I2C serial interface.

Oscillator frequency is set to 600kHz. From the oscillator, a signal goes to the soil moisture probe through a 10k resistor, these two elements act as a low pass filter for the oscillator signal. The output analog signal from the capacitive probe goes through diode to the MCP3221, A/D converter with 12-bit resolution, which converts that data and sends it to MCU. Communication to the MCP3221 is performed using a 2-wire I2C serial interface with available standard (100 kHz) or fast (400 kHz) mode. To be sure that you received correct data, calibration of the Hydro Probe Click needs to be done. The final output value is affected by probe insertion depth and how tight the soil packed around it is. It's recommended that the probe should not be placed on the depth which crosses the limit line on the Click board. The Hydro Probe Click Board™ uses the I2C communication interface and can be supplied and interfaced with both 3.3V and 5V supply voltage. The on board SMD jumper labelled as VCC SEL allows voltage selection for interfacing with both 3.3V and 5V microcontrollers. More information about integrated circuits on this board can be found in the attached datasheets. However, this Click board™ comes equipped with a library that contains easy to use functions and a usage example that may be used as a reference for the development. SPECIFICATIONS Type Environmental Applications The Hydro Probe Click Board™ can be used in agriculture usage, household usage for gardeners, research and forecast, and many more. On-board modules Hydro Probe Click uses the MIC1557 and MCP3221 IC's. Key Features Digital reading of soil moisture. Interface I2C Compatibility mikroBUS Click board size L (57.15 x 25.4 mm) Input Voltage 3.3V,5V PINOUT DIAGRAM This table shows how the pinout of the Hydro Probe Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns). Notes Pin Pin Notes NC 1 AN PWM 16 NC NC 2 RST INT 15 NC NC 3 CS RX 14 NC NC 4 SCK TX 13 NC NC 5 MISO SCL 12 SCL I2C Clock NC 6 MOSI SDA 11 SDA I2C Data Power Supply 3.3V 7 3.3V 5V 10 5V Power Supply Ground GND 8 GND GND 9 GND Ground ONBOARD SETTINGS AND INDICATORS Label Name Default Description LD1 PWR - Power LED Indicator JP1 VCC SEL Left Power supply voltage selection: left position 3V3, right position 5V