When people get lost in the wild at night, they often have only one flashlight. If a helicopter flies overhead, they can send an SOS signal by flashing the light in a specific pattern: three short flashes, followed by three long ones, and then three short again. This is the internationally recognized SOS distress signal, used to communicate with pilots or rescuers. The pattern of light—short and long—is a form of communication protocol.
Similarly, a single-chip microcontroller can process communication protocols using electrical levels instead of light. For example, we can mimic the SOS signal by using high and low voltage levels. A short pulse could be 10 milliseconds, while a long one might be 20 milliseconds. A microcontroller can output these levels through its I/O pins, sending a sequence like three highs, three lows, and three highs again. Another microcontroller receiving this signal can interpret it and perform actions accordingly—like turning on a device or triggering an alert. As long as both sides agree on the protocol beforehand, the meaning of the signal is clear.
This kind of communication is based on predefined rules, just like human language. However, if every company or individual created their own unique protocol, it would become chaotic and incompatible. To avoid this, standard communication protocols like USART, I2C, and SPI were developed. These standardized protocols ensure that devices from different manufacturers can communicate effectively.
Let’s briefly explore some key terms related to communication protocols:
**Serial Communication vs. Parallel Communication**
Imagine you have eight apples to pass to someone else. You could throw them one by one, which is similar to serial communication—sending data bit by bit over a single line. Alternatively, you could toss all eight at once, which is like parallel communication—sending multiple bits simultaneously over multiple lines.
**Full-Duplex vs. Half-Duplex Communication**
In half-duplex communication, two parties can only send or receive at one time. It's like a walkie-talkie where only one person can speak at a time. In full-duplex communication, both parties can send and receive simultaneously, like a phone call where both people can talk and listen at the same time.
**Asynchronous vs. Synchronous Communication**
Synchronous communication requires both devices to share a common clock signal, ensuring they operate in sync. Asynchronous communication, on the other hand, doesn’t rely on a shared clock, so data must be sent with start and stop signals to maintain timing accuracy.
In microcontroller communication, choosing between asynchronous and synchronous methods depends on the application requirements, such as speed, complexity, and hardware constraints. Understanding these concepts helps in designing efficient and reliable communication systems.
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