Things which you can learn:
*Programming and Application of the AT89C2051 micro-controller
*Interfacing of an LCD module
*Application of reed switches and opto-couplers for sensing
*Concepts of EEPROM storage
*Concepts and implementation of I2c protocol
Things which you can learn:
Build a simple circuit which can digitially measure the speed and the distance covered by a vehicle and display it in a awesome 16*2 LCD for you to know.
A 2 0 - p in AT89C2051 microcontroller from Atmel is used here because of its low pin count, affordability and compatibility with CISC-based 8051 family. This
microcontroller features 2 kB of Flash, 128 bytes of RAM, 15 input/output (I/O)
lines, two 16-bit timers/counters, a five-vector twolevel int errupt architecture, a full-duplex serial port, a precision analogue comparator, on-chip oscillator and clock
circuitry. LCD module to display the speed and distance traveled, we have used a 16x2 alphanumeric LCD based on HD44780 controller. The backlight f eat ure of the
LCD allows data to be visible even at night. The readings of the distance traveled are
saved in an external serial EEPROM. Here, a 24C02 serial EEPROM based on Philips
I2C protocol is used.
Let’s assume that the MCU wants to send data to one of its slaves. First, the MCU will issue a START condition. This acts as an ‘attention’ signal to all of the connected devices. All ICs on the bus will listen to the bus for incoming data. Then the MCU
sends the address of the device it wants to access, along with an indication whether the access is a ‘read’ or ‘write’ operation. Having received the address, all ICs will compare it with their own address. If it doesn’t match, they simply wait until the bus
is released by the stop condition. If the address matches, the chip will produce a response called ‘acknowledge’ signal. We have used write operation in this project. Once the MCU receives the acknowledge signal, it can start transmitting or receiving data. In our case, the MCU will transmit data. When all is done, the MCU will
issue the stop condition. This signals that the bus has been released and that the connected ICs may expect another transmission to start any moment.
The Micro-controller based Speedometer cum Odometer is a digital speedometer-cum-odometer can be installed with a motorbike. The circuit uses an AT89C2051 micro-controller, a 16x2 LCD display, 4N35 optocoupler, 24C02 EEPROM and some easily available components. The features of this digital Speedometer cum Odometer are: 1. Digital readout 2. Speed displayed in km/hour 3. Distance traveled displayed in kilometres 4. Readings saved in non-volatile memory (EEPROM) 5. Reliability due to use of the microcontroller 6. No mechanical wear and tear 7. Home-brewed speed transducer/sensor 8. Self reset to zero after completion of 99,999.9 km 9. Easy to build and fix onto the bike