00. First steps into ICs connection and wiring

Owner	MM. G. Sadek
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01. The Objective

In this laboratory tutorial, we will teach you how to identify various ICs and their specification besides tutoring you on how to connect several ICs together using a breadboard.

02. Logic Gates

First, we need to introduce the primary three logic gates which we will use to realize Boolean functions later. Note that each gate has its unique truth table.

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A truth table describes the relationship between the input value and the output value. Also, you must note that any logic signal is either a logic 1 (5/3.3 volts) and logic 0 (0 volts)

02.A. Primary Logic Gates Introduction

We have four primary gates which can be found in any digital circuit, those gates are:

And their inverse gates are:

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Note that those gates are normal gates but we have appended a NOT gate to inverse the output.

02.B. The Breadboard

The typical breadboard is laid out in a matrix of .1 inch spaced holes. Most through-hole Integrated Circuit chips or ICs will fit snuggly in this matrix.

The Horizontal and Vertical Layout

These power rails are also isolated to the right and left sides of the breadboard. If you have to manage two different power supplies or voltages, they can be isolated by keeping them on either side of the board.

02.C. Identifying the ICs Specifications

Those basic logic gates are implemented as small-scale integrated circuits (SSICs) or as part of more complex medium-scale (MSI) or very large-scale (VLSI) integrated circuits. The digital IC gates are classified by their logic operation and the specific logic-circuit family they belong to. As for each logic family, it has its own basic electronic circuit and the following logic families are the most frequently used:

#	Family name	Full name	Transistor type	Logic 1 Voltage specification	Logic 0 Voltage specification
1	TTL	Transistor-transistor logic	Bipolar transistors	5 volts	0 volts
2	ECL	Emitter-coupled logic	Bipolar transistors	5 volts	0 volts
3	MOS	Metal-oxide semiconductor	Field effect transistors	3.3 volts	0 volts
4	CMOS	Complementary metal-oxide semiconductor	Complementary metal-oxide semiconductor	3.3 volts	0 volts

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Note that you need to make sure of the ICs families when connecting them together since different families may need adaptation circuits in order to connect them properly. Therefore, please refer to (https://www.allaboutcircuits.com/textbook/digital/chpt-3/logic-signal-voltage-levels/) to understand how to use different families within the same system.

02.D. Datasheets

In order to know which ICs to buy and how to connect them you must read its datasheet. You can download any datasheet you need from (https://www.alldatasheet.com/). To guide you let's look at the TC74LCX08F datasheet, in this datasheet you must check its voltage operation value (named: Vcc / Vdd) (i.e. how many volts this IC needs in order to operate properly). In this IC it requires an operating voltage between Vcc = 2.0 ~ 3.3 volts. The second important thing is to know the configuration of the pins:

This figure shows that pin 1&2 are the input to the AND gate its output is connected to pin 3.

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To count the pins you need to hold the notch in an upwards direction then start counting in an anti-clock direction.

02.E. Connection Patterns

In order to simulate logic inputs for any digital circuit, you can use push buttons. However, pushbuttons need to have a default value which can be logic 0/1, therefore, there exist two primary patterns which are a pull-down button whose default value is 0 and a pull-up button whose default value is 1. The following figure shows how a pull-down is connected:

Buttons Truth Table:

Button pattern	Pressed	Release
Pull-down	Input ← Logic 1	Input ← Logic 0
Pull-up	Input ← Logic 0	Input ← Logic 1

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Note that, the pull-up is the same as the pull-down except for the voltage and ground are swapped (i.e. resistor → connected on +Voltage and button → connected on to the ground).

Since the push buttons represent our input signals, then LEDs will hold the output signal (i.e. led on → logic 1. led off → logic 0). Any LED has at least two pins which are called the anode and cathode, to turn on the LED you must connect +Voltage to the anode pin and to turn it off connect 0Voltage (i.e. ground) to the same pin.

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Note that, you cannot directly connect +Voltage directly to the anode without burning it. Therefore, you need to add resistance to protect it (please refer to https://mindmatters.ai/2020/10/circuit-patterns-part-i-understanding-circuit-schematics/ and https://eepower.com/resistor-guide/resistor-applications/resistor-for-led/# to understand more on this topic). However, the summary is to connect a 333Ω resistor in series with the anode pin.

03. Classwork

In this tutorial, we are asking you to verify the output of an AND , OR, NOT, XOR gates by connecting two push buttons as inputs to the ICs and an Led as an output on a breadboard, then verify their truth table.