Communication protocols are essential to functional electronics. They provide the instructions for the transfer of data between two hubs. Different protocols have been developed for the application of specific communications rules, similar to how the variety in vehicle design relates to a vehicle’s utility. Today, there are a plethora of protocols that provide an array of advantages conducive to their application.

There are two main types of communication protocols used in embedded systems.  These are broadly classified into two types: Inter-System Protocol (also referred to as External System) and Intra-System (also referred to as Internal System).  An inter-system communication protocol communicates between two devices, while an intra-system protocol is used to communicate within one device. In a testing situation, you could be testing both aspects. For example, you are performing inter-system communications testing when testing comm protocols between devices on a single PCB. On the other hand, you are performing intra-system communications testing when checking to see if the Wi-Fi chip connects to the network on the same PCB.

You need not be totally certain which communications protocols you are working with—modern oscilloscopes can be equipped to decode them. That said, it is a good idea to understand the communication protocols you will encounter in your work.

Intra-System Protocols

As you can imagine, intra-system communication protocols are designed for wired connections. The three major types of these protocols include I2C, SPI, and CAN.

The inter-integrated circuit (I2C) protocol generally entails two-way communication between a master and slave device. After address matching, the master device transmits 8-bit data on a serial data line (SDC), and the slave replies 1-bit of acknowledgment on the serial clock line (SCL), and on. Philips Semiconductors developed this protocol as a way for the CPU to communicate with its peripherals on the PCB.

The serial peripheral interface (SPI) protocol is similar, except that it uses four wires. Motorola developed this protocol to transmit larger data packets and make use of one slave at a time. The CAN, or controller area network protocol, was developed by the Robert Bosch company for the automotive industry. Its structure is closer to the I2C protocol and transmits over larger distances.

Inter-System Protocols

These protocols can be categorized into: USB, UART and USART communication protocols.

The differences between most communication protocols involve addressing, data packet size, factors involved with data transmission speed/updating, network integration/assembly, and indexing or event recording.

IoT Communication Protocols

IoT communication protocols tend to favor transmission quality, scalability, flexibility, and security. Some of the popular wireless IoT protocols include:

• Cellular (3G HSPA, 4G LTE, 5G)
• Wi-Fi
• Bluetooth and BLE (Bluetooth Low Energy, Bluetooth 4.0)
• Zigbee
• Z-Wave
• NFC / RFID
• LoRaWAN

Other IoT communication protocols include custom-made protocols for novel systems that might be used for things like surgically implanted sensors, or a network of digital sensors used in some type of network. Something notable about IoT protocols is that while a device might need a gateway to use one, they are generally configured with worldwide use in mind rather than proprietary.

So, when choosing an IoT communications protocol, you might consider the device it will be installed in, the proximity of other users, the amount of support available for the protocol, and how often it will be used. Neuronic Works has a great table comparing different protocols to help make this choice.

Finding an Oscilloscope to Detect Comm Protocols

TestEquity has offered the best electronics testing equipment and support since 1971. If you are in the market for a new oscilloscope or other devices to help you detect comm protocols, go to the website today to chat with a knowledgeable agent or fill out the form to request a quote.