MindMap Gallery combinational logic circuit
Digital circuits can be divided into two categories based on different characteristics of logic functions. One type is called combinational logic circuits (referred to as combinational circuits), and the other is called sequential logic circuits (referred to as sequential circuits). The characteristic of the logic function of a combinational logic circuit is that the output at any time only depends on the input at that time and has nothing to do with the original state of the circuit. This diagram summarizes the relevant knowledge.
Edited at 2022-06-06 23:27:41El cáncer de pulmón es un tumor maligno que se origina en la mucosa bronquial o las glándulas de los pulmones. Es uno de los tumores malignos con mayor morbilidad y mortalidad y mayor amenaza para la salud y la vida humana.
La diabetes es una enfermedad crónica con hiperglucemia como signo principal. Es causada principalmente por una disminución en la secreción de insulina causada por una disfunción de las células de los islotes pancreáticos, o porque el cuerpo es insensible a la acción de la insulina (es decir, resistencia a la insulina), o ambas cosas. la glucosa en la sangre es ineficaz para ser utilizada y almacenada.
El sistema digestivo es uno de los nueve sistemas principales del cuerpo humano y es el principal responsable de la ingesta, digestión, absorción y excreción de los alimentos. Consta de dos partes principales: el tracto digestivo y las glándulas digestivas.
El cáncer de pulmón es un tumor maligno que se origina en la mucosa bronquial o las glándulas de los pulmones. Es uno de los tumores malignos con mayor morbilidad y mortalidad y mayor amenaza para la salud y la vida humana.
La diabetes es una enfermedad crónica con hiperglucemia como signo principal. Es causada principalmente por una disminución en la secreción de insulina causada por una disfunción de las células de los islotes pancreáticos, o porque el cuerpo es insensible a la acción de la insulina (es decir, resistencia a la insulina), o ambas cosas. la glucosa en la sangre es ineficaz para ser utilizada y almacenada.
El sistema digestivo es uno de los nueve sistemas principales del cuerpo humano y es el principal responsable de la ingesta, digestión, absorción y excreción de los alimentos. Consta de dos partes principales: el tracto digestivo y las glándulas digestivas.
combinational logic circuit
Encoder
Def: Distinguish a series of different things and represent each of them with a binary
Function: Convert each input high/low level signal into a corresponding binary code
Classification
press convert
binary encoder
Binary – decimal encoder
by priority
Ordinary encoder
Features: Only one valid encoding signal is allowed to be input at any time, otherwise the output will be chaotic.
Principle of operation: Circuit that encodes corresponding N = 2n signals with an n-bit binary code
Example: 8-wire-3-wire encoder
Genuine watchmaking:
priority encoder
Several signals are allowed to be input simultaneously, but only the one with the highest priority is encoded. Priority: I7->I0
Example
74HC148
Truth table: (YS', YEX' are used to judge the working status)
attention
Program the ten input signals from I9 to I0 into 10 BCD codes respectively.
I9 has the highest priority and I0 has the lowest priority.
Y3~Y0 are the output terminals of four-digit binary BCD code
Binary-Decimal Priority Encoder 74HC147
Truth table:
attention
Program I9~I0 into 0110 ~ 1110
I9 has the highest priority and I0 has the lowest
The input low-level signal becomes a corresponding decimal code
decoder
Def: Translate the binary code of each input into the corresponding output high and low level signals.
Example
74HC138 - 3-line to 8-line decoder composed of CMOS gate circuits
Truth table:
Two 74HC138 can be used to form a 4-line to 16-line decoder
display decoder
Memory method: 1 circle clockwise, a~f; finally the g in the middle
Given 4 inputs, determine the output: first use the "8421" method to translate the numbers that should be displayed, and then find the bright points accordingly.
Data selector design logic circuit
4-to-1 data selector
Step: 1. First organize the output of one into the form of the sum of the multiplication terms of 1. 2. Propose a specified factor, merge the same ones, and use the factor as the address data later. 3. Use the proposed factors as inputs to the address terminal (A), and the rest as inputs to the data terminal (D).
Book p182 Example 4.5.4
8-to-1 data selector
Step: 1. Convert the multiplication sum formula into the form of the sum of all minimum terms, and multiply D0~D7 in sequence (from small to large, use "8421" to compare) 2. If it is 1, the corresponding multiplied D is 1; if it is zero, the corresponding D is zero. 3. The address terminal (A) is the input variable, and the data terminal (D) is the "01" high and low levels analyzed earlier.
Book p182 Example 4.5.5
1. When you want to generate a single-output logic function, you can first consider the data selector. 2. A data selector with n-bit address input can produce any combinational logic function whose number of input variables is not greater than n 1. 3. Functional comparison method can be used in design. The control terminal serves as the input terminal, and the data input terminal can be synthesized into one input terminal.
Adder
Half adder: Add two 1-bit binary numbers without considering low-order carry
function expression
CO is the carry end
Add two binary numbers and find the binary result
Full adder: adds two 1-bit binary numbers plus the carry from the low bit
function expression
multi-bit adder
serial carry adder (Using Jilian method)
Features: Simple circuit and easy connection; but low speed
Improvement: Carry lookahead adder
data selector
During the transmission of digital signals, a certain one is selected from a set of data and sent to the output end.
Example: 74HC153
Function: Dual 4-to-1 data selector
function expression
truth table
Transformation
Use dual 4-to-1 data selector 74HC153 to form an 8-to-1 data selector.
Methodology: The eight data of "select one of eight" require a 3-digit address code. Therefore, S0 is used as the third address input terminal.
Transformation effect
The transformed function expression:
Transformation for practical applications
Methodology: If A1 and A0 are used as two input variables, and D10~D13 are the input of the third variable or other forms, a combinational logic function with less than 3 variables can be implemented by a 4-to-1 data selector.
Numeric comparator