**Microcontroller**
A microcontroller is a single-chip microcomputer that integrates the core components of a computer onto one chip. It was first introduced in the mid-1970s and has since evolved significantly, becoming more affordable and powerful. This advancement has led to its widespread use across various industries. Examples include motor control systems, barcode scanners, consumer electronics, gaming devices, telephones, HVAC systems, building security, industrial automation, and household appliances like washing machines and microwave ovens.
Microcontrollers can be categorized based on different criteria. For instance, by data bus width, they can be 8-bit, 16-bit, or 32-bit. Based on memory architecture, they can be Harvard or Von Neumann structured. According to the type of embedded program memory, they can be OTP (One-Time Programmable), mask, EPROM/EEPROM, or flash memory-based. Additionally, they can be classified by their instruction set architecture into CISC (Complex Instruction Set Computer) or RISC (Reduced Instruction Set Computer) microcontrollers.
**How Microcontrollers Work**
Today, microcontrollers are found in a wide range of products. If your microwave oven has LEDs or an LCD display along with buttons, it likely contains a microcontroller. Modern cars typically have at least one microcontroller, sometimes up to six or seven, used for engine management, anti-lock braking systems, and cruise control. Almost all remote-controlled devices, such as TVs, video recorders, and high-end audio systems, also rely on microcontrollers. Digital cameras, cell phones, printers, and even some refrigerators contain them. In short, any device that interacts with users often includes a microcontroller.
In this article, we’ll explore microcontrollers to help you understand their functionality and how they operate. Later, we will demonstrate how you can use a microcontroller yourself. As a teaser, we’ll build a digital clock using a microcontroller! We’ll also create a digital thermometer. Throughout the process, you’ll learn how microcontrollers are applied in real-world commercial products.
**Background Knowledge**
If you're unfamiliar with digital logic, gates, and circuit connections, consider reviewing the following topics:
- Bit and byte
- Boolean logic applications
- How electronic gates function
- What is a microprocessor?
A microprocessor is essentially a computer. All computers—whether desktops, large mainframes, or microcontrollers—share common features:
- They all have a CPU (Central Processing Unit) that executes programs.
- The CPU loads programs from storage devices, such as hard drives.
- Computers have RAM (Random Access Memory) for storing variables.
- Input and output devices allow interaction with users.
Unlike general-purpose computers, microcontrollers are "special-purpose" computers designed for specific tasks. They are embedded within other devices to control their operations. These devices usually run a fixed program stored in ROM, consume low power, and are cost-effective. Examples include car engine controllers, microwave ovens, and smart home devices.
Microcontrollers are compact, durable, and often used in harsh environments. For example, those in vehicles must operate under extreme temperatures, from -34°C in Alaska to 80°C in the engine compartment. Despite their simplicity, microcontrollers are essential in many everyday devices.
**Using a Microcontroller**
In the article “How Electronic Gates Work,†you learned about TTL components and basic circuit design. You may have realized that implementing simple functions requires many gates. A microcontroller offers a better solution by replacing multiple gates with software. In this article, we’ll build a digital clock using a microcontroller. While this project might be expensive, it will give you hands-on experience with microcontroller programming.
We'll be using a BASIC Stamp microcontroller from Parallax, which runs the BASIC programming language. Though not used in mass production due to its cost and speed, the BASIC Stamp is ideal for learning and prototyping. It’s small, easy to use, and great for experimenting.
The BASIC Stamp has limited resources—just 14 bytes of RAM and 256 bytes of EEPROM. However, this makes it perfect for learning the basics of microcontroller programming. You can write simple programs, control I/O pins, and interface with sensors or displays.
**BASIC Stamp Programming**
To program the BASIC Stamp, you need to use the BASIC language. If you're already familiar with BASIC, you’ll find it straightforward. If not, don't worry—many programming concepts are similar.
Basic commands include:
- `FOR...NEXT` for loops
- `GOSUB` and `RETURN` for subroutines
- `IF...THEN` for conditional statements
- `HIGH`, `LOW`, `INPUT`, and `OUTPUT` for controlling I/O pins
- `SEROUT` and `SERIN` for serial communication
You can also use advanced commands like `PWM` for pulse-width modulation or `PULSIN` and `PULSOUT` for timing.
**I/O Pins and Communication**
The BASIC Stamp has 8 or 16 I/O pins (depending on the model). These pins can be configured as inputs or outputs. For example, you can use `HIGH 3` to send a 5V signal to pin 3 or `LOW 3` to set it to 0V. You can also read values from sensors using `POT` or `PULSIN`.
Connecting external devices, like an LCD or a temperature sensor, allows the microcontroller to interact with the environment. For example, an LCD can display time or temperature readings, while a DS1620 chip can measure temperature accurately.
**Building a Digital Clock**
To build a digital clock, we’ll use the BASIC Stamp’s I/O pins to drive a 7-segment display. By sending signals to the display, we can show numbers from 0 to 9. To display four digits, we’ll use multiplexing, where each digit is activated sequentially.
Alternatively, we can connect an LCD to the microcontroller for a more modern display. Using the `SEROUT` command, we can send text to the LCD and update the time every second.
**Creating a Digital Thermometer**
To make a digital thermometer, we’ll use the DS1620 temperature sensor. This chip communicates via a serial interface and provides accurate temperature readings. By reading the sensor’s data and displaying it on an LCD, we can build a simple but effective thermometer.
The DS1620 uses a 9-bit two's complement format to represent temperatures, allowing it to measure from -110°C to +250°C. With a little code, we can convert this data into a readable format and display it on the screen.
**Conclusion**
By understanding how microcontrollers work, you can create a wide range of practical devices—from digital clocks to thermometers. Whether you’re a hobbyist or a professional, microcontrollers offer a powerful and flexible way to bring your ideas to life. Start with simple projects, and soon you’ll be building complex systems that solve real-world problems.
| About Bare Wire |
|
Application: Suitable for manufacturing electric motors, windings of electrical equipment, automobile electrical rotors, installation and distribution equipment and other electrical fields.
Name
Conductor
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Dimension(mm)
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Standard
GB;
Packing
160 kg~180 kg ply-wood spool(250*500; 250*600)
Application
Suitable for manufacturing electric motors, windings of electrical equipment, automobile electrical rotors, installation and distribution equipment and other electrical fields.
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