Coordinate Measuring Machine-Microcontroller and Assembly language-Project Report, Thesis of Microcontrollers

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Coordinate Measuring Machine

Project Report

Group Members

Ali Ahsan 73603

Raheel Zia 50289

Azmat Tanvir 50317

Introduction

Coordinate measuring machine (CMM) is a device for measuring the physical geometrical characteristics of an object. This machine may be manually controlled by an operator or it may be computer controlled. Measurements are defined by a probe attached to the third moving axis of this machine. Probes may be mechanical, optical, laser, or white light, among others.

A coordinate measuring machine (CMM) is also a device used in manufacturing and assembly processes to test a part or assembly against the design intent. By precisely recording the X, Y, and Z coordinates of the target, points are generated which can then be analyzed via regression algorithms for the construction of features. These points are collected by using a probe that is positioned manually by an operator or automatically via Direct Computer Control (DCC). DCC CMMs can be programmed to repeatedly measure identical parts, thus a CMM is a specialized form of industrial robot.

Counter

We used 74193 4-bit up/down counter for counting the pulses. Three such counters were cascaded in series to make a 12 bit counter which was able to count upto 2^12 i.e 4096 counts.

8255 Programmable Peripheral Interface

The 8255 has 24 input/output pins in all. These are divided into three 8-bit ports. Port A and port B can be used as 8-bit input/output ports. Port C can be used as an 8-bit input/output port or as two 4-bit input/output ports or to produce handshake signals for ports A and B.

Eight data lines (D0 - D7) are available (with an 8-bit data buffer) to read/write data into the ports or control register under the status of the " RD " (pin 5) and WR " (pin 36), which are active low signals for read and write operations respectively. The address lines A1 and A0 allow to successively access any one of the ports or the control register as listed below:

We used 8255 in Mode 0. In this mode, the ports can be used for simple input/output operations without handshaking. If both port A and B are initialized in mode 0, the two halves of port C can be either used together as an additional 8-bit port, or they can be used as individual 4-bit ports. Since the two halves of port C are independent, they may be used such that one-half is initialized as an input port while the other half is initialized as an output port. The input/output features in mode 0 are as follows:

1. O/p are latched.
2. I/p are buffered not latched.
3. Port do not have handshake or interrupt capability.

CONTROL WORD REGISTER

BLOCK DIAGRAM OF SYSTEM