Automatic watering device

Each of us has long been accustomed to using all kinds of gadgets that make life easier: mobile phones, all kinds of smartphones and tablets, etc. In this article we will replace your familiar watering-can with a technological device for watering flowers that will take care of your favorite indoor plant even if you went on vacation. The device is assembled on the basis of an affordable microcontroller ATMEGA 8 L in a cheap TQFP32 package and a drive from a computer hard drive (HDD) which can be obtained from an old hard drive of a computer. The diagram contains the minimum number of parts and can be supplemented with arbitrary functionality. It is powered by two 18650 Li-ion batteries, 3.7V voltage, connected in series. Watering is done in fixed batches every 24 hours. The only button is a test of work, after pressing it the subsequent waterings will be carried out exactly at the same time to within a second.(I just included it on vacation, no settings, so you can offer it as a gift option, without unnecessary instructions.) Design Features:
  • work from batteries for several months (low power consumption);
  • very accurate irrigation dosages and exact intervals between irrigations;
  • the scheme is not critical to details and their availability;
  • the absence of moving current-carrying parts in the motor, and as a result - durability and reliability when working in water;
  • very low noise level during engine operation;
  • does not require any settings (watering once a day) with sound and light accompaniment;
  • protection against deep discharge of batteries with a sound warning of the need to charge;
  • auto light off at night.
The design is a pump (pump) immersed in a vase with a watering tube and a small electronics block attached to the same vase with water.
Automatic watering device

So, first of all, let's start making the pump.

We need a CD a disc, a 1.5 liter plastic bottle from milk (with a wide neck, ext.diameter 33 mm.), super glue, four core wire (I took the broken wire from charging iPhone), three screws, washers and three nuts and a piece of flexible tube. At the bottle and saw off the neck with a hacksaw for metal exactly along the edge of the “skirt” and dub the resulting cut with sandpaper, a file or a block.
 Automatic watering device
So we are preparing the so-called working chamber of the pump.
 Automatic watering device
Next, we need a CD disk, its internal opening exactly fits the motor, we will make an impeller from the disk. The disk is well cut with scissors, and it's good if it is slightly warmed up hot water to prevent cracking of the cutting edge. We take the sawed off part from the bottle - our working chamber and apply it exactly to the center of the disk with the part where the screw cap was. Outline a circle with a marker and cut out with ordinary scissors. The resulting disc will not be perfectly smooth, but sandpaper can be fixed,the main thing is that the disk with a minimum gap could fit inside the working chamber. It turned out the ring of the future impeller.
 Device for automatic irrigation of plants
Now you need to make blades for the" propeller ". To do this, you will need half the disk. Draw a marker with a 7 mm wide strip and cut it with scissors.  Automatic watering device
Skins and dub it.
 The device for automatic plant watering
Then cut into six equal parts of 13 mm, and bend the pliers on both sides
 Device for automatic plant watering
The further procedure will require maximum accuracy, you need to stick su blades one by one EP adhesive equidistant. Note blades are bent so that they are not raking in the water in the opening of the chamber, and vice versa, as if cast from the center to the hole on the edge.The motor at the same time will only rotate counterclockwise. You can lightly fix it with a drop, level with tweezers and after a little drying add glue to the missing parts.
 Automatic watering device
Try to avoid toxic vapors of the second glue. Then you can dry and varnish. I only had nail polish on hand, it was quite wear-resistant. Then I would need a piece of flexible hose, for example, I took a piece from a construction liquid level. It’s not so easy to drill a hole in the threaded surface of the neck, I had to first practice on a pair of bottles, finally melted it with a soldering iron and smoothly cleaned the inside so that the blade did not touch the irregularities. Insert a piece of hose cut off at a small angle with a force into the hole of the neck and fix it with a moment-like transparent glue . The tube and the opening of the chamber should be of sufficient diameter, about 8 mm. It is advisable to insert the tube not at a right angle to the body, but taking into account the fact that the flow will rotate counterclockwise.
 Device for automatic watering of plants
 Automatic watering device
For fixing the tube it is not advisable to use super glue, t. to. when dry, it strongly damages the surface of the plastic and the body becomes cloudy, losing transparency. Here, a transparent sealant or glue on a helium basis is perfect. Now it remains to assemble the pump, attach the camera to the motor, center it to ensure free rotation of the blades inside, fasten with screws, seal the gaps with a transparent sealant and glue the transparent cover with a hole in the middle of 14 mm from above. . Let me remind you that the impeller will rotate strictly counterclockwise, this is important. Next, we solder the four core wire to the motor and coat the solder with varnish, solder the blue smd LED to one of the windings (through a 1 kΩ resistor), anode to the common one. Now, when it is working, it flickers under water. A few words about the drives from the hard drives. Some types of such motors with the spinning of the rotor by hands continue to rotate in one direction noticeably with better slip than the other. That is, when you try to give a clockwise rotation of the rotor will stop almost immediately. Such devices have a different bearing design and these engines are probably better for our purposes. Although I have both types of work in the water for a long time and are doing great. Windings are checked so. The engine must be with four contacts. We need to find one of the extreme contacts which is the middle point. This output will be connected to the power plus, the rest from it in order - the first, second, third - will be connected to the mospets. Tester measure the resistance between all adjacent contacts. Less resistance will show one of the extreme pins. This is common, it is - on the plus bus. It is extremely desirable to fix the wire on the motor housing, for this you can drill a couple of millimeters holes and press this cable with a copper bracket. When the pump is ready for its pipe worn curved hose with an internal diameter of at least 8 mm. and 20 cm long through which watering will be carried out. Now you can make a PCB and solder the device. The board is made of one-sided fiberglass LUT. I note that the picture of the trace and layout of the printed circuit board is not mirrored in order to make it easier to check when installing. When printing LUT, you need to turn it in the mirror, or use the archived SprintLayout file.
 Automatic watering of plants
You can also paint the nail polish in this way: Rod from the ballpoint pen it heats (a little!) over the flame of the lighter, turning it evenly and pulling it out evenly. Next, the thin end is cut off by the blade. Thus, a conical tube with a very small outlet is obtained. It can be inserted into a 1.5 cc syringe, and having previously collected the usual nail polish to draw the tracks of printed conductors on the board. After drying, the board is lowered into the pickling solution. It can be a mixture of copper sulphate with salt 1: 3, and water. The solution is prepared as concentrated as possible. Heating is required, for example, over a candle flame. The process is accelerated by constant stirring.Copper sulphate is sold in any agricultural store.
 Device for automatic irrigation of plants
The microcontroller is powered by a parametric voltage regulator assembled on the elements D1, R7, Q1. The value of the resistor is chosen so that the own consumption of the stabilizer is as low as possible. Much lower than the so-called "Krenka". Such a schematic solution allowed us to reduce consumption to 0.3 mA. This is very important, because the duration of our design depends on this without recharging the batteries. Transistor Q1 - npn is not critical. Zener diode for voltage stabilization 5.1 V. It is possible from charging for mobile. The quartz resonator is 32.768 kHz. Normal quartz hour. From quartz watches. The keys used in the scheme are MOSFETs that are dropped from the motherboard of the old computer. SMD LED. You can from the LED tape. Speaker - any suitable in size. You can speaker from a mobile phone. Installation of the circuit should start with a voltage regulator, and then measure the voltage at its output (capacitors C2 and C3). It should be 5 volts. Then you can solder the microcontroller and everything else. In the circuit, the unused and diluted pins of the microcontroller PB0, PB1, PD6 can be used to connect peripherals. The microcontroller program algorithm is constructed as follows. The controller is configured to operate in asynchronous mode. Interruptions occur once per second, at which time the program calculates the time, flashes a short time LED (every 10 seconds) and immediately goes into sleep mode to save power consumption. If the hour meter becomes zero (immediately after resetting the button or after 24 hours), the controller's supply voltage is measured four times and compared with the internal reference voltage source. If the voltage is lower than the allowable one, the circuit emits periodic audible signals notifying that the battery is low, after fifteen signals the controller adjusts to power down mode and goes into sleep mode until the next recharge of the batteries. If the voltage is above the threshold value, a beep sounds and the LED lights up. Next, the initial position of the rotor of the engine is established and short pulses are successively applied to the motor windings.The durations of the pulses and the pause between them follow gradually decreasing, thus a set of rotations of the motor and further constant rotation of the blade are provided, thus ensuring an accurate portion of watering. At the same time, the LED flashes synchronously. At the end of watering, the circuit goes back to standby mode for counting time. In this mode, it is most of the time, this results in a high energy efficiency (about 0.3 mA). During the main program, the controller is clocked from an internal oscillator with a frequency of 8 MHz, and in the sleep mode, an external clock quartz allows read the time accurately. Short-time flashes of the LED every 10 seconds signal the operation of the device. From the beginning of the zeroing of seconds, it will flash for 30 minutes, and then the flashes will stop for 12 hours and will resume after another 12 hours. Thus, if you set the watering at 00 hours, then the flicker will not occur at night, but only from 12 pm.
Firmware file Dviglo_mega_avr_V.hex When firmware needs to be set to work from internal RC oscillator 8 Mhz source code in VR Studio file Dviglo_mega_avr_V.rar If there is an arduino board, you do not need a programmer. (detailed instructions) Files in the proshivka_arduinoi folder.
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