Current hardware version: V1.2.0

Compiled GUI for Windows 7 OS and later: MHTG_V10X_GUI.zip

Source code: GitHub

USB Driver (CP210X): Windows 7/8/8.1 or Windows 10

Behold, an easy to use, Arduino based, programmable water pump controller for 12/24VDC water pumps ranging up to 50/100W power output, respectively. It's capable of controlling the irrigation of a small hydroponic growing system. There's a standalone Windows application to interact with this device and change its settings on-the-fly through micro-USB connection. For default settings read the relevant points in the "operation" section.

Features

• Power input: 12VDC @ 4A (50W max) or 24VDC @ 4A (100W max)
• Screw terminals (below v1.2.0), spring clamp terminals (v1.2.0 and up)
• Reverse polarity protection on power input connector
• N-channel power MOSFET PWM motor driver
• Water pump speed adjustable between 0-100% (PWM-frequency adjustable down to 245 Hz)
• Programmable on/off timer and service mode
• +5V voltage regulator for the onboard ATmega328P microcontroller running at 16 MHz
• Micro-USB connector with CP2102 USB-controller for communication and microcontroller programming
• Important settings are saved into the ATmega328P's internal EEPROM and loaded when necessary
• Two-click automatic firmware update in the Windows GUI
• 2x 10k NTC temperature sensor connectivity (XH2.54-2P connector), adjustable beta-value, selectable units (Celsius, Fahrenheit, Kelvin for hardcore people)
• 1x I2C device connectivity (XH2.54-4P connector) preferably for a 20x4 character LCD with I2C backpack
• 2x tactile switches (hardware reset and mode button)
• 2x status LEDs, green: standby, red: water pump running
• Informative data layout when a 20x4 I2C LCD is connected

Operation

Powering up

There's no on/off switch on this device so it's always active when it has power through the screw terminal / spring clamp terminal or USB-connector. Apply input voltage according to your water pump rating (12V for 12V pump, 24V for 24V pump). You can hot-swap on all connectors. The reverse polarity protection doesn't let components to suffer damage. The device loads the last saved settings and gradually ramps up the water pump to its set speed.

Timer

An internal timer ensures the water pump is switched on and off according to the set intervals. By default the timer is set to 5 minutes on-time and 60 minutes off-time.

Water pump speed

By default the water pump is driven at 100% speed. Adjust this speed with the Windows GUI application so that it doesn't blow off system components. Default PWM-frequency is set to 490 Hz, which is a default value of Arduino devices. The firmware is programmed to use the TimerOne-library which enables more sophisticated wave-shaping (frequency- and phase-correct PWM) thus drives the motor more smoothly.

Service mode

Press the "Mode" button to enter into service mode. In this mode the water pump is disabled regardless of timer status and the red LED blinks rapidly. During this time you can service your hydroponic growing system without the fear of nutrient water splashing everywhere. Press the "Mode" button again to resume normal operation. The timer continues counting time in the background so it's possible that you resume operation when the water pump is off anyways.

Temperature sensing

You can connect up to 2 10k NTC thermistors (labeled as "T_ext/T_e" and "T_int/T_i") to measure temperatures and choose sensor count and temperature unit in the Windows GUI. By default Celsius unit is selected and temperature sensors are disabled. In case of the wire is too short it can be extended, polarity doesn't matter.

LCD

If you connect a 20x4 character LCD with I2C backpack, then a beautiful and informative layout will welcome you with a nice timer progress bar of my creation.

Configuration

To change device settings connect a micro-USB cable to the device, start the Windows GUI application select the appropriate COM-port, click on the "connect" button, make your changes and click on the "write settings" button.
It's also possible to change settings via the Command Line Interface. Using this method the host computer can have any operating system that can run Arduino IDE. Once its Serial Monitor is running at 250000 baud speed text commands can be entered.

I2C-wire color-coding

• black: GND
• red: +5V
• yellow or white: SDA
• blue or green: SCL

Recommended power supply

• Mean Well LRS-100-12 100W/12V/0-8,5A or equivalent for 12V water pumps
• Mean Well LRS-150-24 150W/24V/0-6,5A or equivalent for 24V water pumps
• 12/24V battery + solar panel and charger

Compatible water pumps

12V (max. 50W) / 24V (max. 100W) bilge pumps or similar

Package content

• 1x Hydroponic Water Pump Controller
• 1x XH2.54-4P to 1x1P female DuPont adapter for the I2C connector (15 cm, 0.5 ft)

Weight

44 grams

Water pump, LCD, temperature sensors are not included! They are mass produced items. Get them from here:

• 1M NTC 10K 1% Thermistor Temperature Sensor
• I2C LCD Yellow/Black or I2C LCD Blue/White