Universal remote control receiver

Here we use again a hybrid module Aurel to produce, with very few components around, a ray of radio on-off dual channel capable of working with the old codes to 12 bits as with the most secure, those who respond KeeLoq protocol. We can build a hybrid module AM or FM, depending on the benefits that remote control is sure.

Specifications
- Working frequency: 433 MHz
- Channels: 2 (monostable)
- Coding: 12 bit or KeeLoq (with self-learning)
- Issuers associate: 60 max
- Power supply: 12 Vdc
- Buttons for manual activation relay
- Ability to use different radio modules:
• BCNBK (superregeneration AM)
• RXAM4SF (superheterodyne AM)
• RX4M50FM60SF (superheterodyne FM)

Almost every audio / video are equipped with a remote push-button but to turn on / off the chandelier in the room, still we rise from our chair. Fortunately, the electronics are there to help those who want to go further in the comfort of the remote control: it allows the radio, it does not aim at the camera's sensor to control and it passes through the walls.

Our achievement
This article proposes to construct a receiver universal remote control with two channels: universal, first because it allows room to mount as many types of radio receiver Aurel hybrid modules, you can choose based on that you would expect (or superheterodyne superregeneration AM or FM).
For example, if the area where you want to operate is particularly blurred, you choose a superheterodyne radio receiver module, if the most important to you is the economy, you take a radio receiver AM superregeneration.
Of course, depending on the choice, you must choose a corresponding pocket transmitter.
Universal, then in terms of encoding / decoding: obviously, TX and RX must use the same type of code, but our decoder circuit uses a self-learning code, capable of running 12-bit systems (those with dip- switch) as the coding KeeLoq microcontrollers.
In this case we can store in the decoder codes of 60 (maximum) of different issuers.
In the first case, however, the number of transmitters used is virtually limitless because it is enough to set the various issuers of the code used in the transmitter with which one has self-learning.
The two systems can not operate simultaneously and therefore it is necessary to choose between two options.
The small size allows the receiver to insert inside the devices to control.
Two additional micropoussoirs can operate locally, when necessary, relay output, nothing prevents also to parallel (or instead) of these switches micropoussoirs existing home. You see here the term "universal" is not in vain! This radio receiver can be used for operating electric locks, door openings and portals of all kinds, solenoid sprinkler, burglar alarm systems or video surveillance systems, etc..
Whatever your requirements, the radio receiver can satisfy them: it is easy to make and install, and it is reliable, very small, it will find its place everywhere.

wiring diagram

Figure 1: Diagram of the universal receiver transmitter.

The wiring diagram of Figure 1 is extremely simple but can still be distinguished several distinct areas:
• RF receiver (U2): choice between AM or FM, whose role is to demodulate that transmits the TX;
• decoding circuit (U1), providing control information and transferring the loads to activate;
• interfaces and power management devices;
• power stage.

The hybrid module U2 receives on pin 3 (antenna) the signal produced by the RF transmitter, demodulates and forwards it onto the spindle 14. For the receiving section, it is possible to use three different hybrid modules (they have the same pinout and function with the same voltage supply): BCNBK models, and RXAM4SF RX4M50FM60.
The role of these modules is simply converted into a sequence of logic levels 0 and 1 the received signal: in fact, on pin 14, we find the same feed as that produced by the encoder TX. The data are then demodulated by U2 appliquéesà pin 2 (IN) decoder U1. When the decoding phase is over, what remains is the information represented by the two logic states that can control both outputs CH1 (Pin1) and CH2 (pin 3).
The current available release is not sufficient to directly drive the two power relays and it is therefore necessary to use two transistors. U1, across networks and R2/R3 R4/R5 bias, the driver transistor T2 (BC547) and T1 (BC557) which, in turn, control relays RL1 and RL2. The relay contacts are normally open and connected to terminals OUT1 and OUT2.
D1 and D2 protect T1 and T2 surges caused by inductive component of the corresponding relay coil.
The two relays, namely: TX with battery, failure of the latter, etc.. Can be activated manually using the buttons P1 and P2. The receiver requires a power supply of 12 Vdc and a maximum current of 100 mA for portable applications you can use a battery or a rechargeable battery and fixed a small block 230 V power
The 12 V input directly feeds power relays and the remaining portion of the circuit is powered with a voltage of 5 V stabilized obtained through the network corresponding to the zener DZ1.
The capacitor C2 of 470 uF deals filtering low frequency components present in the feed line and C1 100 nF, filters out interference due to higher frequencies, from, for example, switching relays and sparks occurring on its contacts, but also during the energization of the neon tubes.

Figure 2: Schematic implementation of the components of universal receiver transmitter.

Figure 2b: Drawing scale 1, the circuit board receiver universal remote control.

Figure 3: Photograph of a prototype of the plate receiver universal remote control.

Figure 4: An example of TX keychains among those that can be used to attack the receiver universal remote control described in this article.

is a specific decoder for HCS301 (in addition to 12-bit code type MM53200) with two outputs for relay control. This is a small circuit CMS 24 x 18 mm 5-pin SIL standard 2.54 mm pitch used for connections with the outside: the positive supply, the common mass, the data input and output CH1 (opto-isolated) and CH2 (TTL-compatible).
This is a simple decoder stage mounted at the output of stage and radio receiver that is compatible with most receivers Aurel. It contains a microcontroller PIC12C509 CMS programmed with the software necessary to decrypt the signals sent by the mini transmitter HCS301 encoder (for this algorithm contains KeeLoq) about it, it goes without saying that the TX handheld as the decoder Manufacturer must contain the same code. In the decoder there is also a serial memory EEPROM 24C08 type, in which the microcontroller writes the codes received during the stationary phase of self-learning so that their software allows the couple to 60 different TX (maximum) provided, however, they all have the same Manufacturer Code. The five pins of the decoder are IN, CH1, CH2, +5 V and GND, the other contacts being used for programming at the factory on the writing of the Manufacturer Code and the resident program with the algorithm KeeLoq. The input IN is where the data coming from the stage radioreceptor Aurel, which may belong to any type (RF 434/868 MHz modulation AM / FM), provided he accepts a bandwidth approximately 2400 bps and TTL pulse format.
Power must be carefully stabilized at 5 VDC. The control output operates in CH "sink", so if it is enabled it makes the mass: that is why the charge is applied between it and the positive supply.
CH1, photo-isolated, also accepts the connection of loads supplied by more than 5 V (up to about 50 V) and CH2 will not accept more than 6 to 7 V in pull-ups. The CH2 output is normally "low" and becomes "high" when the code is recognized. Dipswitch two micro-switches to select the operating mode (see Table), that is to say, to choose the type of decoding (12 bit or KEELOQ). The top left button is used during the phase of self-learning code.
Figure 5: MA4 decoder.

Figure 6: Photograph of a hybrid Aurel modules can be used to achieve this receiver universal remote control (it is a superheterodyne FM high sensitivity).

Figure 7: Coupling devices possible.

Microchip HCS301 encoder and decoder MA4
Over the years the radio controls were quite advanced in the direction of greater safety. Originally a radio carrier command to a receiver to activate an output (see Guglielmo Marconi turning the lights remotely from Sydney) but with the proliferation of remote controls, the risk of interference has increased significantly. Hence the need to implement encryption systems of varying complexity.
The first codes were fixed: it allowed many to avoid interference but no interceptions (evil).
With the current codes to "rolling code", that is to say coded variables, this problem has also been removed: the "data stream" generated by the TX every time varies depending on a pseudo-algorithm random. Thus, only a receiver knowing this algorithm can decode the signal. And of course, the most variable component of the stream is long, the lower the risk of interference and interception.
Microchip has implemented in recent years the method of coding the most secure: KeeLoq. The integrated circuit is HCS301 KEELOQ encoders used in transmitters and Aurel MA4 decoder was made for optimum coupling. It is built on a PCB of 24 x 18 mm with 5-pin pitch of 2.54 mm. This decoder incorporates a microcontroller PIC12C509 programmed with the algorithm KeeLoq and is also equipped with an internal EEPROM which stores it, for self-learning, up to 60 transmitters on two different channels. In this regard, recall that all issuers and MA4 decoder must be programmed with the same Manufacturer Code.
We have already said that the two-channel receiver can operate on AM or FM, as the RF hybrid module chosen (U1).
The table in Figure 7 shows the five possible combinations for this assembly, most simple, using a module AM superregeneration, the most powerful, where you fit a superheterodyne FM RX.

The practical realization
The practical realization of this receiver universal remote control does not present any difficulty of any kind whatsoever. The plate consists of a single sided PCB, which 2b gives a scale drawing. Start by soldering the "jumper" in the upper left of the small plate: a remnant tail component will do. Insert and then solder all components (as shown in Figures 2a and 3), starting with the resistance: they are mounted upright in trombone, except R1 conventionally lying.
Continue with the diodes D1 and D2 rings oriented toward the center of the plate and DZ1, ring to module U1. Mount C1 and C2, the latter being more than to C1/U1. Mount the transistors T1 and T2, without the inverted and flat side up. Mount both micropoussoirs. Mount the two relays and three terminals.
You only have to mount the two modules, standing out for components U1 and U2 inwards.
Solder a wire antenna of 175 mm (a piece of insulated copper wire) to the point ANT, bottom left. Once everything checked several times (or short-circuit between tracks or pads or cold solder joints), you can proceed to self-learning (that is to say, the coupling between the receiver and transmitter or transmitters).

Self-Learning
It only remains to put the receiver on and check if everything works properly. First, proceed to erase the memory of MA4 decoder, which may contain test data disrupting our first tests. To do so, press and hold down the small button mounted on the module MA4 for more than three seconds, the LED shows red, lighting up / extinguishing, that the erasure has occurred.
To pair the TX should first decide what type of transmitter you want to work: with 12-bit code or protocol with HCS. Depending on what choice we have to deal with the micro-switch MA4 as shown in Figure 5. To store a transmitter, it is necessary to press again the little button of MA4 (this time under three seconds) and thus obtain the LED lighting: we then have four seconds to press the button of the first channel TX.
Slacken the button when the LED goes out and urge it again to verify that the relay sticks well and that the channel has been memorized. The coupling sequence is then repeated identically for the second button of the TX. Now if we press the button 1 or button 2 on the radio, we hear the corresponding relay sticking.
To couple other TX, repeat the procedure as described above, in the case of a 12-bit code, set the dipswitch as in the first TX memorized. Install the plate in (or near) the device to be controlled (in a electrical wall box, for example), depending on its destination.