In this clause I will talk of the design of an automatic curtain drive installed along my balcony. In that location we grow flowers that are harmful to direct sunlight. In gain, in the summer, if the windows of the balcony are union, in straightforward sun, the air happening the balcony quick overheats. However, when there is no direct light, it is advisable to open the curtains - the shadow likewise does not contribute to the maturation of colors. Therefore, to maintain standard lighting on the balcony, I automated the curtains.

Mechanics

The curtains were originally on the balcony. There are two of them, both suspended happening a metal cable stretched stunned from the ceiling from one and only fence of the balcony to the other. It is clear that you need to move both curtains at once, while due to the detrition of the curtains on the cable (it is quite rough), the required force should be quite large. To boot, sometimes there may glucinium obstacles in the agency of the curtain, for example, an ajar balcony window, which boost increases the strength requirements.
Thus, the drive must be reigning and authentic enough - there is often high humidity on the balcony, a rather large temperature difference in winter and summer is possible. Consequently, I made the basis of the drive a car power window drive. It has sufficient power, is capable of delivering high torque (a dirt ball pitch is collective into IT) and is rattling reliable.

A diagram of the mechanical part of the drive is shown below: Details of the design. A elastic roller with a groove on which a coil of rope is wound is fixed on the power window beat back shaft (on the left of the plot). The drive is decorated on unmatchable of the walls of the balcony. The same crimper is sessile to the opposite wall, through which a rope is also thrown. After that, the rope is pulled, thus that the friction of the rope on the drive roller is enough to move the curtains. The antonym ends of each curtain are related to to the rope so that when the motor rotates, the curtain moves apart Beaver State moves. To check the operation of the labour, I made its reduced mannikin. The power window drive and an independent roller were fixed on the display panel, pulled a rope between them, after which information technology was possible to check the operation of the electronics and measure the force developed by the drive.

Photo of the drive itself on the layout: Arsenic you can meet from the photo, a fairly large thin plate is attached to the power window drive (I secondhand textolite). A metallic corner is attached to that with two holes through which the rope is passed. IT is needed so that the coil of rope connected the crimper is not at sea, for this the holes in the corner are made at different heights congenator to the plate.

To the right of the corner are the limit switches needed to stop the curtains to extreme positions. In order to indicate these positions, ii plastic tubes are put happening the rope (only one of them is circumpolar in the exposure next to the lower switch). The tubes are organized so that when the curtain reaches its extreme position, one of them presses the switch, and for reliable pressing, a metal-looking plate is attached next to each of the switches, which presses the tube to the switch.
Trine metal posts attached to the plate are needed to secure the drive underwrite.
Both rollers for the rope are made of piece of furniture wheels. Exploitation a practice session and a file, a groove mustiness be grooved in each of them; two turns of rope must be ordered in the groove of the drive roller. The effort roller is mounted on the shaft by tension, while the hole in it had to be bored to square, since the ram shaft is square.
The drive is attached to the balcony wall using suitable furniture corners (one of them is visible in the exposure connected the left). The power window effort has enough mounting holes, sol there are no mounting problems.

Type of drive, already attached to the wall and closed by a incubate: Ready to tighten the rope, a special screw with a nut is used, to which the ends of the rope are attached: The end of unity of the curtains is too attached to it.

Electronics

Every last of my electronics is divided into two parts - power and control condition. The main undertaking of the force unit is to furnish force to the drive motive. The power window drive can squander really high current. To reduce this incumbent, I reduced the power provide voltage of the drive to 5 volts, but all the same, the maximum current used up by the motor can reach 3A. To provide this current, I used a pressman power supply equal to of delivering voltage of approximately 30V and current up to 0.7A, too as a DC-DC converter up to 5V. By cloudy the voltage, DC-Direct current is quite equal to of delivering the desired current.
The power issue of the motor is controlled by a effectual relay designed to change the polarity of the signal, and the MOSFET, which controls the electric potential supply to the centrifugal. Thanks to the wont of MOSFET it is possible to adjust the engine speed, but at the moment this feature is not used.
Also on the power side are stabilizers designed to power the control electronics and an engine tycoo negative feedback circuit. The stabilizers are powered by a frown voltage circuit of the power provision, the voltage there does not exceed 12V.

Power lap

The control electronics is represented past the STM8S microcontroller. The control performs quite a lot of functions - measuring illumination, qualification a decision to start the thrust, controlling the berth of the curtains by the limit substitution, controlling the power of the drive, controlling the drive in non-automatic modality - according to the commands of the removed control. To boot, a tuner mental faculty on the NRF24L01 and a 1-Wire bus are connected to the restrainer, through which three temperature sensors are connected. Using the radio module, you can control the drive and say the temperature values at varied points on the balcony and on the street, but at the moment the second radio mental faculty is related to only to the bread board, so I leave not consider this functionality further.

The used tycoo supplying from the printer has an input for putt IT into Stand-by country. I also use information technology, owed to which the energy economic consumption of the structure is small. The course of study takes into account that the power append enters the operating mode with a certain delay, and after 30 seconds of inactivity of the push, the mightiness supply once more enters Sales booth-by mode.

Indication of drive operation - victimization a three-color LED (only blue and red diodes are used). Racy lights up when emf is practical to the motive, red starts to flash periodically in the presence of errors in the drive. The total of flashes allows you to determine the error number.
For the sound signaling of some events (for example, when bountiful a command to close already closed curtains), the ride motor itself is used. A PWM signal with a small responsibility bike is applied to it, as a answer of which the motive beeps quite loudly.

Control circuit

A photoresistor attached by a sucking cupful to the window is old as a light sensing element. Since the suck loving cup may fall off the window, a small button is located side by side to the photoresistor. While the suction cupful is held on the window, the release is pressed against the window. If the suction transfuse falls inactive, the automatic rifle operation of the drive stops and the red diode flashes. If the sensor is not related to the connector, and then this is also detected by the accountant.
Type of light sensor:

Since the illumination of the detector can change dramatically - ascribable various outbreaks on the Street, variable cloud cover, the data from the sensor moldiness be filtered. I have implemented the following processing algorithm: data from the sensor is digitized at a frequency of 10 Hz, and written to the array. Once a second, the apprais of this array is averaged (first of wholly, this is necessary for filtering noise and flashes). Further, the obtained values are added to some other raiment with a dimension of 600 elements, after stretch the end of the regalia, recording starts from its beginning. Besides, this array is analyzed every second - the controller calculates what percent of the array elements is less than a certain threshold (with raising illumination, the voltage at the turnout of the photosensor drops). If the values of more than 66% of the elements are to a lesser degree the specified threshold, then it is considered that the miniature is quite high, and curtains can be closed. So, filtering periodic changes in illumination. At the aforementioned time, a limitation is also imposed on the frequency of the drive - in automatic mode, the motor turns on no longer than at one time every ten proceedings.

As I mentioned supra, it is mathematical to control the curtains from the remote. Using the remote control, you can completely open and close the curtains, part open them, start the motor by the instantaneous value of illumination. When dominant from the remote control, there are no restrictions connected the oftenness of operation of the drive.
It is also conceivable to programmatically reboot the controller.
When moving the curtains, the controller monitors the status of the limit switches. If, afterwards the start of apparent movement, the corresponding switch does not operate within 20 seconds, the motor stops working. To continue the operation of the drive aft troubleshooting, just need to reboot the controller.

Each electronics are installed in a standard pliant case:

Single of the switches is needed to transfer the electronics to automatic rifle mathematical process, the second allows you to completely turn off the power to the causative.
Using Gob 3.5mm knucklebones, a light sensing element, TSOP for receiving data from the remote control, and external temperature sensors are connected to the device.
The LED is closed with a whiten cap - so it can be seen at any angle.