A simple infrared remote-password lock design and implementation (1)

O introduction

As the science and technology improvement and social economic development, electronic locks to replace the traditional mechanical lock has become an inevitable trend.

In the past, based on the SCM password lock system, directly to weave a good password is stored in the chip EPROM, but difficult to implement password modifications; such as to complete the change password feature, the use of tablets, serial E2PROM. This article studies and design of a microprocessor infrared remote-control electronic locks, not only has a normal password lock locked, unlocked smart control, alarm, etc., but does not extend E2PROM, can achieve an 8-bit passwords any modified functionality saves hardware resources, reduces the system volume, this is the design of an innovation point. In addition also adds remote control lock features. So the system not only low cost, strong, more applicable to the normal human body should not close to special occasions, such as high radiation area, high-incidence areas, etc.

1 system hardware design

1.1 system design

The system consists of an infrared transmitter module and native processing receiver module two-part, system design diagram shown in Figure 1.

Transmitter module and native core processing receiver module using AT89S52 microcontroller AT89C2051 and. Infrared signals to communicate via the serial port transceiver, two-part serial works and the communication baud rate is set to.

AT89C2051 microcontroller is a streamlined AT89C51 version, only 20 pin, small; 2.7 ~ 6 v wide voltage range of work; low-power idle and power-down mode.

The SCM meets the system low voltage power supply, low power, easy to carry.

In native processing receiver module, using AT89S52 microcontroller, the SCM has three timer.

Sets the password and press the key to unlock, press the interval was designed more than 3s automatic reset function, using timer T0 and T1 T2 scheduled implementation; timer to set the baud rate of serial port communications.

1.2 infrared transmitter module design

Infrared transmitter module is only a handheld remote control MCU and by AT89C2051 keyboard circuit, press K and infrared emitting diode.

Transmitter schematic diagram shown in Figure 2.

Transmitter module set password must be the same as with native receiver module (set password method see section 2.2.1), the password is stored in the RAM memory of 31H ~ 38H unit.

In standby mode, the system works in idle mode, press the key K is pressed, the system power-on password, then click Send. The advantage of doing this is that the password will not only be able to follow any of the changes, and the host remote control lock, only press one key to complete the lock, convenience to users.

1.3 native processing receive circuit design

Native processing receive circuit control core is AT89S52 microcontroller.

External keyboard circuit, IR receiver, unlocked circuit, alarm circuit key indicates the circuit and, circuit schematic diagram shown in Figure 3.

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