Week 11 and week 14 Progress

In this 4 weeks, I am focusing on how to make presentation and research about the materials specification and budgeting and also my skills on presentation. 

forecast budget on materials and component

NO	ITEMS	QUANTITY	PRICE (RM)
1	Walker	1	125.00
2	Power Window motor (12V)	2	76.00
3	Rubber wheel ( 4 inch diameter)	2	9.00
4	Castor wheel ( 2 inch diameter)	2	9.00
5	Relay (5V)	4	10.00
6	Relay ( 6V)	3	7.50
7	Relay (12V)	2	5.00
8	Resistor (10K)	10	1.00
9	Resistor (1K)	8	0.80
10	Capacitor	4	1.60
11	Crystal (20Mhz)	1	2.00
12	Diode	5	1.50
13	Transistor (Tip 41)	4	1.50
14	Lead-acid battery (12VDC)	1	45.00
15	Lead-acid battery (10VDC)	1	35.00
16	Box	1	20.00
17	Keypad switch	1	18.00
18	Microchip Base	1	12.00
19	Photoelectric sensor (NPN)	2	700.00
20	Microchip	1	25.00
21	Voltage regulator LM7805	1	1.50
22	Wrapping cable	5 meter	9.00
	Estimation Cost (RM)		1108.90

Specification of Remote Sensing Walker

Table : Specification forecasti of remote sensing walker.

Item	Specification
Frame	Height : 95 cm Wide (up):30 cm x 50 cm Wide ( bottom): 45 cm x 55 cm
Rubber wheel	Dia.3.5 inch @8.89cm
Castor wheel	Dia.1.5 inch@ 3.81cm
Weight	7.8 kg
Hand switch box	7cm x 5cm
Remote control range	5 meter
Control panel box	25 cm x 20 cm
PIC battery	10VDC (1000mA)
Motor Battery	12VDC ( 4Amp)
Batter life	10 hours

This block diagram is the flow process of the system.

 

12V POWER SUPPLY:

·         To give supply for the whole circuit, including power window motor, photoelectric sensor and transceiver device.

·         Some of the device require voltage regulator circuit to be trigger, and some of the device need to be trigger by relay circuit.

PHOTOELECTRIC SENSOR:

·         It is function for emergency brake for the motor.

·         The detection is using infrared signal and react in certain range (300mm front) (500mm wide) (200mm height).

TRANSMITTER:

·        Transmitter is constituted by AT90S2323 microcontroller and TLP434 RF transmitter module at 418MHz.

·        The safe transmission of the data based on the transmission of 4 bytes with serial form at 2400 bps (bits per seconds).

RECEIVER:

·         Receiver is constituted by RF receiver module RLP434A at 418MHz

·         The RLP434A is an RF receiver module with receipt frequency at 418MHz with ASK modulation

·         2 outputs from this module, the digital, with levels from 0v to VCC (5 volts) and the analog output.

MICROCONTROLLER (PIC16F877A):

·         Program the PIC, it used MPLAB IDE version 7.40 and WinPIC800 as compiler.

·         Purpose to program this PIC is to make the system can control the movement of the remote sensing walker.

·         This PIC is react as same as the brain of the human, it will give instruction to the actuator and circuit as programmed.

POWER WINDOW MOTOR:

·         Move when generated with 12v supply and a signal from the PIC16f877A.

·         Can move forward or reverse or right or left according to the instruction that have been programmed to the PIC.

 MATERIALS AND EQUIPMENTS:

 Remote Control Circuit

  2 Channel RF Remote Control Transmitter

According to Vasilis (2004), the transmitter is constituted by AT90S2323 microcontroller and TLP434 RF transmitter module at 418MHz. This design of the transmitter is good for more battery economy and safe transmition of the data.

·         The battery economy is made by the used of power down mode of AVR. In this case the AVR (automatic voltage regulator) goes to sleep with less than 1uA (microampere) current and wait for external interrupt on pin PB1 to awake from sleep and continue operating. If the S2 key is pressed, the logic of this pin goes to '0' (0V) and AVR awake from the sleep mode (because PB1 is INT0) and will check if the S1 key is pressed. If not, the AVR will assume that the S2 is pressed. If yes, the logic of this pin and PB1 (through 1N4148) goes to '0' (0V). When the INT0 pin (PB1) of AVR goes to 0V, the transmitter TLP434A is working. If pressing of the switch S1 or S2 is stopped, the TLP will stop working.

·         The safe transmission of the data based on the transmission of 4 bytes with serial form at 2400 bps (bits per seconds). 1st and 2nd byte are for recognition of valid remote control from receiver (like ID bytes), 3rd byte is command byte. The relays status dependent by the value of this byte. Finally, the 4th byte is the checksum of the earlier 3 bytes.

   2 Channel RF Remote Control Receiver

·         According to Vasilis (2004), the receiver is constituted by RF receiver module RLP434A at 418MHz. The microcontroller AT90S2313 and the 2 relays can handle any electric (or electronic) device up to 10 Amps (the contacts of relays are 10Amp at 250Volts). The RLP434A is an RF receiver module with receipt frequency at 418MHz with ASK modulation. There are 2 outputs from this module, the digital, with levels from 0v to VCC (5 volts) and the analog output. Analog output is not used. The transmitters send 4 bytes with 2400bps 4 times and the receivers RLP-434A collect them and move them to AT90S2313 to RxD pin, PD0. The antenna is used a cable of 30 - 35cm long. The reasons to select AT90S2313 (20pins) instead of AT90S2343 (8pins) is because with AT90S2313 it can drive up to 14 relays with.

 Photoelectric Sensor

 

 Figure : Photoelectric sensor (Pepperl + Fuchs, Inc.)

Photoelectric sensor use light to detect the absence or presence of an object. Detection occurs if a light beam is interrupting and reflected by the object moment sense. The advantage of photo sensor is there no physical contact with the target .The object can detect a varying distance ranging from one inches to several hundred feet. A self-contained photoelectric sensor contains the optics, along with the electronics. It requires only a power source. The sensor performs its own modulation, demodulation, amplification, and output switching. Some self-contained sensors provide such options as built-in control timers or counters. Because of technological progress, self-contained photoelectric sensors have become increasingly smaller. Remote photoelectric sensors used for remote sensing contain only the optical components of a sensor. The circuitry for power input, amplification, and output switching are located elsewhere, typically in a control panel. This allows the sensor, itself, to be very small. Also, the controls for the sensor are more accessible, since they may be bigger. When space is restricted or the environment too hostile even for remote sensors, fiber optics may be used. Fiber optics are passive mechanical sensing components. They may be used with either remote or self-contained sensors. They have no electrical circuitry and no moving parts, and can safely pipe light into and out of hostile environments.

 PIC16F877A Microcontroller

According to McFarland (2006), microcontroller is highly integrated chip that contains all the components comprising a controller. Typically this includes a microprocessor, memory, and input/output ports. A microcontroller is designed for a very specific task to control a particular system. The components can be simplified and reduced, which cut down on the production costs. Below is the microcontroller architecture:

 Central Processing Unit (CPU)

The CPU is the brain of the microcontroller which is responsible for locating and taking the correct instruction, decoding it and executing it. This unit connects all parts of the microcontroller through an 8-bit data bus and a 5-bit address bus and determines the transfer of data from one location to another within the microcontroller via the controller. The main components of the CPU are the computer operational codes (Opcode), the Program Counter (PC), the Instruction Register (IR), the Arithmetic Logic Unit (ALU) and input/output ports.

 Computer Operation Codes (Opcode)

The first step of a design of a microcontroller is to determine the type of operations it has to perform. The operation code is part of the instruction set and essentially encodes all the functions of the microcontroller, thus providing a unique code for each necessary operation and instruction set in.

 Program Counter (PC)

The program counter is a register that holds the address of the next instruction to fetch from the program memory and is updated by one at every instruction cycle, unless an instruction changes the PC. The processor then take the instruction from the memory location pointed to by the PC, places it in the Instruction Register (IR) and then increments itself. The PIC16C57 has an 11-bit PC used to access the 2048 x 12 program memory.

 Instruction Register (IR)

The currently executing instruction is stored temporarily in the instruction register. The processor interprets the contents of the IR via the instruction decoder and determines the type of operation to be executed depending on the instruction set.

            

               

                                  Figure : Instruction registers (McFarland, 2006).

 The Arithmetic Logic Unit (ALU)

The Arithmetic Logic Unit (ALU) is the ‘core’ of any processor which performs the calculations (arithmetic, boolean and shifts) on the operands. The ALU is basically a number crunching mechanism which computes the results based on the control signals provided to it by the opcode part of the instruction set. The opcode is used to select between the arithmetic, boolean and shift operations.

 

Figure : Block diagram of ALU (McFarland, 2006).

 Input/output Ports

Ports refer to a group of pins on a microcontroller which can be accessed simultaneously, or on which we set the desired combination of zeros and ones, or read from them an existing status. They represent the connection of the CPU and the outside world. The ports are basically I/O registers which can be read and written under program control. There are 16 fully programmable I/O on the PC16C57 which can be used to change for both input and output.