1. The serial port and COM port refer to the physical interface form (hardware). TTL, RS-232, and RS-485 refer to the level standards (electrical signals). 2. When connecting devices, usually only GND, RX, and TX are connected. Vcc or +3.3V power lines are generally not connected to avoid conflicts with the power supply of the … Read more
Point: 1. The serial port and COM port refer to physical interface types (hardware). TTL, RS-232, and RS-485 refer to signal level standards (electrical signals). 2. When connecting devices, generally only GND, RX, and TX are connected. The Vcc or +3.3V power line is usually not connected to avoid conflicts with the power supply of … Read more
What are the differences between serial ports, COM ports, TTL, RS-232, and RS-485? We often encounter these in our projects, so let’s summarize them. 1. Serial ports and COM ports refer to the physical interface form (hardware). TTL, RS-232, and RS-485 refer to the level standards (electrical signals). 2. When connecting devices, generally only GND, … Read more
In electronic circuits, it is necessary to establish the transmission and exchange of electrical signals between different devices, and these signals must be transmitted through specific interfaces. However, different level interfaces have different principles and application scenarios. How should we choose interfaces based on the circuit? 1. TTL Level Interface Principle: The TTL (Transistor-Transistor Logic) … Read more
Differences Between TTL and RS232 Levels What are TTL levels, CMOS levels, and RS232 levels? What are their differences? Generally speaking, CMOS levels have a higher noise tolerance than TTL levels. (1) TTL Level Standards Output L: <0.8V; H: >2.4V. Input L: <1.2V; H: >2.0V The output low level of TTL devices must be less … Read more
1 The Origin of Serial Ports The serial port emerged around 1980, with data transmission rates ranging from 115kbps to 230kbps. Initially, the serial port was designed to connect computer peripherals, such as mice, external modems, old cameras, and graphics tablets. It can also be used for interconnecting two computers (or devices) for data transmission. … Read more
The Concept of Levels: What are voltage, current, and power? Radio enthusiasts are well aware of these. However, when it comes to the term “level”, few can explain it clearly. Although people frequently encounter high levels, low levels, level gain, and level attenuation in circuits, and even multimeters essential for electricians have methods for measuring … Read more
A few days ago, I saw discussions in my technical group about the topic of “TTL, RS232, and RS485 transmission distances“. Today, I took some time to share relevant content. Overview Many readers might not know what TTL, RS232, and RS485 are, so this section provides a brief overview of them. 1. TTL Level TTL: … Read more
Problem: I used a USB to TTL board to program the STC89C52RC microcontroller. I connected the board’s RX to the microcontroller’s TX (P3.1), the board’s TX to the microcontroller’s RX (P3.0), and GND to GND. After making the connections, I couldn’t download the program, and I kept receiving the prompt “Please power on the MCU.” … Read more
Electronic products, such as computers, mice, chargers, and even cars, have many interfaces around us. This article will introduce you to these interfaces, what they look like, where they are used, how to use them, and their principles. This article serves as a simple description for beginners. 1. Serial Port 2. UART 3. TTL Level … Read more