Internet of things (IOT) system for retrieving lost campus card
Project lifecycle: Jan.2016–Aug.2016
Table of Contents
A system combining offline Internet of things equipment and online cloud platform based on RFID, Internet of things and cloud service technology is designed for retrieving lost campus card.
The implementation process is shown in Figure 1:
Step 1: when someone (card picker) picks up the campus card lost by others, they can find the storage device nearby. After the campus card is close to the RFID module, the cabinet door of the storage device will open automatically, and the card picker will put the campus card in it;
Step 2: The MCU unit in the storage device sends the location of the storage cabinet and the campus card information to the server through the GPRS module. The server transmits the received data to the network platform, and sends the verification code and the location information to the person who has lost the campus card
Step 3: according to the push information, the person who lost the campus card will go to the designated location and enter the verification code to get the card.
2. Overall composition
The overall composition of the IOT system includes: electronic tag, RFID module, GPRS, ARM MCU, storage device, cloud server, etc., as shown in Figure 2:
3. Hardware design
The system hardware mainly includes MCU, power module, RFID reading module, GPRS communication module, relay control module and storage cabinet.
STM32f1 series chips are used to form the core board, which has fast processing speed and low power consumption, and can meet the requirements of the system.
3.2. Power module
The power supply includes 12V, 5V and 3.3V, in which 12V power adapter is used to convert AC to 12V DC, and LM7812 voltage regulator chip is used for secondary voltage stabilization; LM2940 and LM1117 are used to output 5V and 3.3V respectively. The above voltage stabilizing chip has reliable performance and stable voltage stabilizing.
3.3. RFID reading module
MFRC-522 module is selected as the RFID reading module to read the serial number information in the electronic tag.
3.4. GPRS communication module
The module uses SIM900A high-performance industrial grade GPRS module, and uses GPRS network for long-distance data transmission.
3.5. Relay control module
Using the relay control module to control the switch of the cabinet.
3.6. Storage cabinet
In order to reduce the cost, the storage cabinet is made up of acrylic board cabinet and electromagnetic lock.
4. Software design
The system software mainly includes MCU program and cloud server.
4.1. MCU program
4.2. Cloud server
The cloud server as the center of data storage and management, on the one hand, it can receive data from MCU, on the other hand, it can push messages to users.