Design of Smart home based on Linux (3)

2 Hardware Design

The hardware design of this subject includes the main controller, data transmission design, data acquisition design, control drive design, display design, and door access design.

2.1 Host Controller

According to the plan three select s3c6410 master chip, s3c6410 is a low power, cost-effective rsic processor, based on the ARM11 core, built-in powerful hardware acceleration, display processing and scaling, motion video processing, audio processing [9]. This is a smart home processor is the perfect choice, hardware performance can be fully realized. This design chooses the OK6410 Development Board based on the s3c6410. The Development Board has the following characteristics [10]:

(1) 12MHz, 48MHz, 27MHz, 32.768KHz clock source, support 5V voltage supply;

(2) Using 8-bit dial switch to set the system start mode;

(3) A total of 4 serial ports, including 1 five line RS 232 level serial port (DB9 female);

(4) Touchpad interface support 4-wire resistive touchpad, LCD interface support 4.3-inch TFT Lcd, using touch screen to realize human-computer interaction;

(5) 1 CMOS camera interface, support itu-rbt601/656 8-bit mode, use 10*2 pin connector;

(6) 1 100M network ports with Dm9000ae, with connection and transmission LEDs.

This topic OK6410 Development Board's RS232 level serial port and the PC connection, 3 three-wire TTL level serial port (20pin2.0mm spacing plug seat) is connected with the ZigBee coordinator, the network port connects with the PC, the 10*2 pin connector is connected with the CMOS camera.

The OK6410 Development Board is shown in Figure 2-1:

2.2 Data transfer

The data transmission of this subject is divided into the data transmission between the PC and the main control board, which is connected with the network twisted pair and the serial line, the communication between the main control board and the wireless network sensor, the use of TTL level to the serial port, the communication between wireless network sensor and wireless network sensor, using ZigBee protocol stack And the camera communicates directly with the main controller via the 10*2 pin connector. The specific design block diagram is shown in Figure 2-2:

Figure 2-2 data transmission design block diagram

2.3 Data Acquisition Section

Data acquisition includes temperature and humidity collection, illumination acquisition, video data collection.

2.3.1 Temperature and humidity sensor DHT11

The temperature sensor uses a DHT11 temperature and humidity sensor with a calibrated digital signal output. Its circuit principle is shown in Figure 2-3:

Figure 2-3 DHT11 temperature and humidity sensor circuit schematic diagram

2.3.2 Illumination Sensor

The light-intensity sensor adopts the sensitive photoresistors sensor, when the ambient light is not up to the set threshold, the Do terminal outputs high, and the do terminal outputs a low level when the ambient lighting exceeds the set threshold. The circuit schematic diagram 2-4 shows:

Figure 2-4 illumination sensor circuit schematic diagram

2.3.3 COMs camera

This subject COMs camera uses the hardware is OV9650 as the image acquisition sensor. The interface between OV9650 and s3c6410 is illustrated in Figure 2-5:

Figure 2-5 interface schematic diagram of OV9650 and s3c6410

2.4 Wireless Transmission Module

This topic uses the ZigBee module of the net bee to carry on the wireless transmission.

The characteristics of the net Bee ZigBee are as follows [11]:

(1) High-performance, low-power 8051 microcontroller core;

(2) to adapt to the 2.4GHz IEEE 802.15.4 RF transceiver;

(3) Wide supply voltage range (2.0~3.6v);

(4) watchdog, battery monitor and temperature sensor;

(5) 8-way input 8~14-bit ADC;

(6) 2 usart,1 infrared circuit which supports multiple serial communication protocols;

(7) 1 Universal 16-bit and 2 8-bit timers;

(8) 21 General purpose I/O pins, 2 with 20mA current absorption or current supply capability;

(9) Small size QLP-40 package, 6mmx6mm.

The circuit schematic diagram 2-6 shows:

Figure 2-6 zigbeeCC2530 circuit schematic diagram

ZigBee p0_2, p0_3 respectively and OK6410 Development Board on the RXD1 and TXD1 connection to achieve data transmission; ZigBee P0_6 and DHT11 data port connected to achieve temperature and humidity data transmission; p1_4, p1_3, P1_2, p1_ 1 respectively received ul2003a chip drive lamp, adjustable photosensitive sensor data port connected P1_5 port, P1_6 connected to the motor (air conditioning) drive, control the rotation of the motor, p1_7 connected to the motor (curtain) drive, control the curtain switch; P0_4, p0_ 5 Connect with the Access control module, read the information of the access card, p0_0 the signal line of the rudder and control the switch of the door.

2.5 Control Drive Section

Control of the air conditioning motor and the control of the curtain motor using the LN298 Motor Drive module, its schematic:

Figure 2-7 LN298 circuit schematic diagram

The control of the luminaire is driven using the ul2003a drive chip. The +5v,16 pin of pin 8th is connected to the GND of the power supply. The schematic diagram of the logic circuit is as follows:

Figure 2-8 ul2003a logic circuit schematic diagram

2.6 Display Section

The display part of this topic uses 4.3 inch TFT screen, LCD hardware mainly includes LCD glass panel, LCD driver and LCD controller. The interface signal between LCD controller and LCD driver is mainly: Vd0~vd23, VCLK, HSYNC, VSYNC, Vden, Lcd_pwern, Tsxp, TSYP, TSXM, tsym[12]. Here the vd0~vd23 is the LCD pixel data signal line, used to transmit the data to be displayed; VCLK is an explicit clock signal, each VCLK signal, the LCD controller transmits a pixel of data to the LCD;HYSNC is a horizontal synchronization signal, also known as the line synchronization signal; VSync is a vertical sync signal, Also known as frame synchronization signal, Vden is a data enable signal, TSXP, TSXM is used to determine the coordinates on the x-axis of the plane, TSYP, Tsym is used to determine the plane on the y-axis of the coordinates. The hardware block diagram between the TFT touch screen and arm is shown in 2-9:

Figure 2-9 TFT touch screen and s3c6410 hardware interface diagram

2.7 Access Control Section

Access control system using RFID Card reader Module RC522, the use of the servo controller door switch, when the key is incorrect card will appear buzzer alarm, until the correct key to the door to stop the alarm. The basic block diagram of the Access Control section is shown in 2-10:

Figure 2-10 Basic block Diagram of Access control section

Behind the design of the smart home based on Linux (4).

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Design of Smart home based on Linux (3)