Wednesday, August 31, 2011

Nokia 3315 / 3310 LCD interfacing with Microcontroller

    Displaying content on a normal alphanumeric display is very limited ,we have to be limited with the font size and we can't draw any graphics also. but convention Graphics lcd are really very expensive so here is the solution, you can use Nokia 3315 / 3310 monochrome  LCD to display your large font text and graphics . the reason behind using this LCD is ,it is really very cheap and can be powered with 3 volts supply. so it is really good for battery powered application.

Project Description 

       however you can use almost any microcontroller (with capability to work on 3v ) do display content on this LCD, may be that micro controller is PIC , AVR or MSP 430 , but in this demonstration we will be using Microchip PIC 18F458 Microcontroller.

    The software program for this project will be written in C with MPLAB IDE , This LCD has a resolution of 84x48 pixel.

Circuit Description

Circuit Diagram of  Nokia 3315/3310 interface with micro controller

Accurate LC inductance /Capacitance Meter

About The Project 

This is accurate home made LC inductance/capacitance meter built with very common components which are very easy to find all around . The range of this LC Meter is extremely good at measuring very low value of capacitance and inductance.

LC Meter's Inductance Measurement Ranges:
- 10nH - 1000nH
- 1uH - 1000uH
- 1mH - 100mH

LC Meter's Capacitance Measurement Ranges:
- 0.1pF - 1000pF
- 1nF - 900nF


it auto calibrate when power up , so there is no chances of human error in calibration. we can also re calibrate at any instance of time by pressing the reset button.this meter is completely auto range.

Components.

  • No particularly accurate components are required, except for one (or more) accurately known "external" capacitors used to calibrate the meter.
  • The two 1000pF capacitors should be fairly good quality. Polystyrene are preferred. MKT are fine. Greencaps tend to drift in value too much. Avoid ceramic capacitors. Some of these can have high losses (and it is hard to tell).
  • The two 10uF capacitors in the oscillator should be tantalum (for low series resistance/inductance).
  • The 4MHz crystal should be a genuine 4.000MHz one, not something approximate to 4MHz. Every 1% error in crystal frequency adds 2% error to the indicated inductance value.
  • The relay should be a low current one. The PIC can only provide about 30mA of drive current.
  • Don't forget the "catch" diode across the relay coil!


REMOTE CONTROLLED LAND ROVER without Microcontroller

Robotics is a fascinating subject— more so, if you have to fabricate a robot yourself. The field of robotics encompasses a number of engineering disciplines such as electronics (including electrical), structural, pneumatics and mechanical. The structural part involves use of frames, beams, linkages, axles, etc. The mechanical parts/accessories comprise  various types of gears (spurs, crowns, bevels, worms and differential gear systems), pulleys and belts, drive systems (differentials, castors, wheels and steering), etc. Pneumatics plays a vital role in generating specific pushing and pulling movements such as those simulating arms or leg movements. Pneumatic grippers are also used with advantage in robotics because of their simplicity and cost-effectiveness. The electrical items include DC and stepper motors, actuators, electrical grips, clutches and their control. The electronics part involves remote control, sensors (touch sensor, right sensor, collision sensor, etc), their interface circuitry and a microcontroller for overall control function.

Project overview
What we present here is an elementary robotic land rover that can be controlled remotely using primarily the RF mode. The RF remote control has the advantage of adequate range (up to 200 metres with proper antennae) besides being omnidirectional. On the other hand, an IR remote would function over a limited range of about 5 metres and the remote transmitter has to be oriented towards the receiver module quite precisely. However, the cost involved in using RF modules is much higher than of IR components and as such, we have included the replacement alternative of RF modules with their IR counterparts for using the IR remote control. The proposed land  rover can move in forward and reverse directions. You would also be able to steer it towards left and right directions. While being turned to left or right, the corresponding blinking LEDs would blink to indicate the direction of its turning. Similarly,during reverse movement, reversing LEDs would be lit. Front and rear bumpers are provided using long operating lever of micro switches to switch off the drive motors during any collision. The decoder being used for the project has latched outputs and as such you do not have to keep the buttons on remote control pressed for more than a few milliseconds. This helps prolong the battery life for remote. The entire project is split into sections and each section is explained in sufficient detail to enable you not only to fabricate the present design but also exploit these principles for evolving your own design with added functions/ features.


Microchip SPI Basics Tutorial For PIC18

Introduction 
             The Serial Peripheral Interface (SPI) is one of the popular embedded serial communications widely supported by many of today’s chip manufacture and it considered as one of the fastest serial data transfer interface for the embedded system. Because of its special in/out register configuration, the SPI master device could transfer its data and at the same time it receive a data from the SPI slave device with the clock speed as high as 10 MHz. Beside its superior data transfer speed; SPI also use a very simple data transfer protocol compared to the other serial data transfer methods. When the SPI master device want to send the data to the SPI slave device then the SPI master will just simply shifting its own data through a special 8-bits register and at the same time the SPI master will receive the data from the SPI slave into the same register as shown on this following picture.

           With this circular shift register connection between the SPI master and the SPI slave devices, the complete data transfer from both devices will be accomplished in just 8 clock cycles. This means the SPI devices only need about 0.8 us to complete transfer the 8-bit data if we use 10 MHz clock. One of the drawbacks using the SPI especially when we use multiple SPI slave device is the SPI slave could not initiate sending its own data to the SPI master device, all the data transfer initiation is always come from the SPI master. The SPI master device has to poll each of the SPI slave devices to know whether the SPI slave device has a data to be sent to the SPI master device or not.

           Polling the entire SPI slave devices will eventually consumed the SPI master resources when the SPI slave devices to be polled increase, therefore some of the SPI slave device is equipped with the interrupt pin to notify the SPI master device that it has a data to be read.