26-10-2016, 11:04 AM
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INTRODUCTION
History of Compass:
The compass was invented in China during the Han Dynasty between the 2nd century BC and 1st century AD, where it was called the "south-governor" (sīnán 司南). The magnetic compass was not, at first, used for navigation, but for geomancy and fortune-telling by the Chinese. The earliest Chinese magnetic compasses were possibly used to order and harmonize buildings in accordance with the geomantic principles of feng shui. These early compasses were made with lodestone, a form of the mineral magnetite that is a naturally-occurring magnet and aligns itself with the Earth’s magnetic field. People in ancient China discovered that if a lodestone was suspended so it could turn freely, it would always point toward the magnetic poles. Early compasses were used to choose areas suitable for building houses and to search for rare gems. Compasses were later adapted for navigation during the Song Dynasty in the 11th century.
Based on Krotser and Coe's discovery of an Olmec hematite artifact in Mesoamerica, radiocarbon dated to 1400-1000 BC, astronomer John Carlson has hypothesized that the Olmec might have used the geomagnetic lodestone earlier than 1000 BC for geomancy, a method of divination, which if proven true, predates the Chinese use of magnetism for feng shui by a millennium. Carlson speculates that the Olmecs used similar artifacts as a directional device for astronomical orgeomantic purposes but does not suggest navigational usage. The artifact is part of a polished hematite bar with a groove at one end, possibly used for sighting. Carlson's claims have been disputed by other scientific researchers, who have suggested that the artifact is actually a constituent piece of a decorative ornament and not a purposely built compass. Several other hematite or magnetite artifacts have been found at pre-Columbian archaeological sites in Mexico and Guatemala.
The high-performance Atmel 8-bit AVR RISC-based microcontroller combines 32KB ISP flash memory with read-while-write capabilities, 1KB EEPROM, 2KB SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three flexible timer/counters with compare modes, internal and external interrupts,serial programmable USART, a byte-oriented 2-wire serial interface, SPI serial port, 6-channel 10-bit A/D converter (8-channels in TQFP and QFN/MLF packages), programmable watchdog timer with internal oscillator, and five software selectable power saving modes. The device operates between 1.8-5.5 volts.
By executing powerful instructions in a single clock cycle, the device achieves throughputs approaching 1 MIPS per MHz, balancing power consumption and processing speed.
2. HMC5883L sensor board:
The HMC5883L is a surface-mount, multi-chip module designed for low-field magnetic sensing with a digital interface for applications such as low cost compassing and magnetometry. The HMC5883L includes our state-of-theart, high-resolution HMC118X series magneto-resistive sensors plus an ASIC containing amplification, automatic degaussing strap drivers, offset cancellation, and a 12-bit ADC that enables 1° to 2° compass heading accuracy. The I 2C serial bus allows for easy interface. The HMC5883L is a 3.0x3.0x0.9mm surface mount 16-pin leadless chip carrier (LCC). Applications for the HMC5883L include Mobile Phones, Netbooks, Consumer Electronics, Auto Navigation Systems, and Personal Navigation Devices. The HMC5883L utilizes Anisotropic Magnetoresistive (AMR) technology that provides advantages over other magnetic sensor technologies. These anisotropic, directional sensors feature precision in-axis sensitivity and linearity. These sensors’ solid-state construction with very low cross-axis sensitivity is designed to measure both the direction and the magnitude of Earth’s magnetic fields, from milli-gauss to 8 gauss.
3.Nokia 5110 display (pcb version)
It has 8 pins, connect these as follows (or adjust the code below for the correct arduino pins):
1. VCC (3v arduino output)
2. GND – Not needed, but if you do some sites say to connect via a small capacitor
3. SCE – Pin 7
4. RST – Pin 6 also spelled pushbutton or simply button is a
5. D/C – Pin 5
6. DN – Pin 4
7. SCLK – Pin 3
8. LED (backlight) – No needed, but if you do, remember to use a current limiting resistor!
5. 2x push-button:
A push-button (also spelled pushbutton) or simply button is a simple switch mechanism for controlling some aspect of amachine or a process. Buttons are typically made out of hard material, usually plastic or metal.[1] The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed. Buttons are most oftenbiased switches, though even many un-biased buttons (due to their physical nature) require a spring to return to their un-pushed state. Different people use different terms for the "pushing" of the button, such as press, depress, mash, hit, and punch.
Advantages and Disadvantages
ADVANTAGES:
• Does not require any electrical power to function (except for night illumination), therefore is not affected by loss of power.
• Tends to be more stable than a fluxgate compass. Usually, the bigger the compass card diameter on a magnetic compass, the more stable, (and also the easier to read).
• Depending on design and location, may be used to take bearings, as well as to display vessel's heading.
• Heading display is analog, preferred by many mariners.
• Can be compensated for magnetic deviation by the use of adjusting magnets.
• History of reliability.
DISADVANTAGES:
• Lack of digital output make compass inappropriate for interface with electronic navigation devices (although some magnetic compasses can be fitted with special electronic pickoffs to interface with an autopilot).
• Compass usually must be located at the steering station for reading by the helmsman. It can not be located remotely in a low magnetic interference area (ie: under a sleeping bunk).
• Second (backup) magnetic compass cannot be located close to the primary magnetic compass. The two compasses will interfere with each other, making both inaccurate.
• Magnetic compasses sometimes can be rendered inaccurate by a lightning strike on the vessel, or by arc welding in the close vicinity of a magnetic compass (compass should be temporarily removed while welding in the vicinity).
• Must be corrected for magnetic variation, which changes with location on the earth.
APPLICATIONS
• SONAR
• For Navigation purpose
• Used in Ships, plane for proper direction