RFM001 RF modules induction electric lock control design

In recent years, with RF IC card technology in various fields of application of the increasingly sophisticated and extensive, the use of radio frequency card for key RF induction electric lock, because of the unique easy operation, high security performance at new electronic locks in occupies a pivotal position.

RF induction electric locks usually contain the password of RF IC card (RF key) to replace the traditional metal production of keys.

In the read password, generated by an electronic controller, and then open the signal power, driving electric control door lock switch. This has the advantage of first, eliminate the illicit copying key, followed by the access to personnel information management for the creation of the conditions. However, the lock structure becomes complicated and unreliable factors increases, costs are rising sharply, and the addition of a certain operation, compared with mechanical lock also increased with difficulty. Visible, RF induction electric locking in safety performance improvement and reliability, cost, feasibility, and a series of new problems. If, by design, not to pay attention and take measures, it has become a kind of trouble.

You can view, was too complex controllers are often the source of "trouble".

Based on these considerations, the RF induction electric lock controller, no matter what the technology design should follow a principle that, in ensuring the basic functions of the controller to be as simple as possible. Here, the basic functionality of a very important. In other words, the beginning of the design, be sure to carefully define the function, the firm removed those dispensable. Some electronic locks, besides the switch function, increased many unusual or difficult-to-use features, the result is not only useless addition of a number of costs, but also greatly reduced reliability. This is not an important factor of success.

This article describes the induction lock controller, makes every effort to meet the practical, simple design principles to ensure electronic locks to adequately make, that is more secure at the same time, maintain a relatively low cost (does not degrade performance as prerequisite), improving the reliability.

1 design specification

1.1 feature requirements

An induction lock controller basic functions should include:

¡Ó sensitive keys open/close the door;

¡Ó sensitive keys (RF IC card) to add and clear;

◇ Lock electromagnetic clutch-driven;

◇ Controller working state of sound, light tips;

◇ To save electric power for limited-time operation timed out after the turn to sleep;

◇ Low voltage alarm;

◇ Key wakeup feature.

To achieve these capabilities required by the man-machine interface: startup key (wake up) key, clear the parent key key, add the child key keys, clear the child key keys, status indicators, low voltage led, buzzer.

1.2 operational requirements

Management of radio frequency key generally use authorization card issuing system or card grading system.

In order to take into account security and ease of use requirements, using the master key-a key secondary mode management key. Parent key functions as a system password, the key to open the door (volume keys) are added and deleted.

How to add a simple and effective, is the key to decide important induction lock performance.

In the past to see binary dial switch, by deleting the child key mode of the main problems are cumbersome and inefficient. Used to add, delete key, use the adjacent sub key is a single drop, is a natural and easy way. The following are the key to this design provides additions and operation requirements.

① clear parent key.

First press the delete key, parent key after pressing the Start button, and then release the Start button. Parent key delete keys hold 5 s, heard a long tone after the deleted parent key. Since then double light flashes, and five short blasts to indicate how the parent key not set.

② setting the parent key.

In a dual-lamp blinks while tweets after five short tones, induction lock controller is preset to the parent key of induction key induction. Hear a short tones, press the Add button, the buzzer emits two long tone, at this point that represents the parent key is set to complete. Each lock can have only one master key, the master key can only be used to add a key, you cannot open the door.

③ increasing child key.

Press the start key, the master key induction, hear a short tones, and then apply to join the child key induction. Hear a short tones, followed by adding key, hear 3 short tones that complete a set of sub key. By increasing the key immediately hear a short tones, indicates that you would like to join the child key has been set to repeat the error is. Master card do this increases as a duplicate error. Continuous increase, simply repeat the induction to increase new sub key, then press the Add button, the maximum increase 29 sub key.

④ open/close the door.

Press the start key, the circuit from sleep to read key State. At this point, the available keys when you heard correctly induction, a short tones, the status light flashes, door lock clutch power movement, the door opened. Open the State continued after 5 s, the status light is off, the clutch break, Gates recovery off State.

⑤ to clear a single sub key.

Press the start key and the parent key induction, hear a short tones, followed by clear key, you will want to clear the child keys of the previous child key induction, hear a short tones, then press the clear key, after hearing the second short tones that clear finished. If you wish to clear the child key as the first, its previous sub key is the master key. If you wish to clear the child keys of the previous child key has been cleared, but not yet added to the new sub key, and then clear previous sub key, and so on. If you plan to clear other sub key, repeat the above operation.

⑥ clear all sub key.

Press the start key and the parent key induction, hear a short tones, again with the parent key induction, heard another short tones, press and hold the clear key 5 s, listen to two short tones with a long sound that is about all sub key is cleared.

Controller of some fundamental work status:

① Restart dynamic.

Power-on, if the master key has been set up, the battery is notUnder voltage, the dual lamp is off; if the battery voltage, under voltage led light. If the master key is not set, the dual lamp blinks while calls five short tones.

② sleep state.

If s does not contain any 10 read key action occurs, the circuit is automatically transferred to the sleep state in order to save power.

③ battery voltage alarm State.

Battery voltage ≤ 5 v low voltage lights burning bright. You should replace the battery as soon as possible.

④ failed State.

In addition, the clear operation, if it is found that the status lights continuously lit, indicates that the circuits are failures, should be suspended.

　　

The above operations and related sound and light hints, see table 1.

1.3 technical parameters

　　

Induction lock controller technology parameters listed in table 2.

2 induction lock controller hardware design

Control circuit chip (U1), key storage (U2), RF module (U3), man-machine interface components, electromagnetic clutch drive circuit and RF antenna, use DC 6 V (4-5, battery) power.

Figure 1 is induction lock controller circuit schematics

　　

RF module selection based on United States Texas Instruments ' (TI) RF module RFM01.

Low power consumption, card speed is high, the wiring simple. It requires connection of 1 inductance value is 430 ~ 460 μ H, Q values greater than 15 antenna coil. You can also select based on United States ATMEL company U2270B RF module, but performance is marginal.

SCM selection ATMEL company 89C2051.

Its ports and ROM to meet the functional requirements of the circuit. The operating frequency of the microcomputer 11.059 2 MHz (cannot be higher or lower than this value, because the software use this frequency and radio frequency module matches). If you also want to extend the use of other features, such as 12 or 16 keys keyboard, add calendar clock or extended memory, you can choose the port number and ROM more SCM. For greater reliability should use OTP-compatible microprocessor.

Key storage use ATMEL company 24C02, 30 keys can be stored.

If you plan to store more keys, should use the series a larger capacity models. For greater reliability can be United States compatible models XCOR company.

This circuit uses a PNP transistor in power play magnetic clutch driven circuit, can drive the load current in the various within A 0.8 electric locks dedicated electromagnetic clutch or motor.

If you plan to drive greater load, you can change to relay drive, transistor output relay coil can be received, but this will increase the power consumption.

Consists of four buttons, 2 LEDs, 1 buzzer composition of man-machine interface, in order to complete the add, delete, start, and other necessary actions.

Radio frequency module by matching the antenna coil parameters must be accurate, or else the card performance does not meet design requirements.

Production of antennas, you must use instruments to measure its parameters. Here's a set and the antenna parameters RFM01 match, as shown in table 3. The coil body to the key type induction of recognition distance 80 mm, on the recognition that induction distance 120 mm.

　　

This circuit uses 89C2051 －integrated comparer constitutes battery undervoltage detection circuit.

In the event of undervoltage, light emitting diode.

In order to maximize battery life, when a few seconds there is no action occurs, the circuit automatically enter a low-power state, the so-called "sleep state".

This is done by software control 89C2051 and RF module working state.

3 electronic lock controller software design

Hardware needs and high efficiency of the software, in order to achieve a variety of inductive electronic locks.

Software source code using the C language, the final code curing in the Flash ROM 89C2051. The flowchart in Figure 2.