A System-on-chip, or SoC, is the overall processing unit of a small digital device, like a smartphone or an embedded system. It is the homologue of a motherboard on a laptop. However, it has some significant differences.
First off, the SoC is not quite as powerful as a motherboard. It is usually fitted with lesser rated components so that it doesn’t generate more heat than it can dissipate at a time. So, you can find a motherboard attached to several high-frequency processing cores, while an SoC will have lesser cores or lower-rated cores.
Another important difference is that the motherboard is more of an attachment interface. The components of an SoC are mounted on it to remain compact in the smart device. The motherboard’s components are attached to it via ports and terminals. Hence, a motherboard will take up more space than an SoC.
The basic components of an SoC are listed below.
1. Processing cores
SoCs typically have more than a single core, which represents processing units. They exist in the form of microprocessors, digital signal processors, or application-specific instruction-set processors (ASIP), depending on the system’s complexity.
The processors designed for SoCs are based on the Advanced RISC Machines architecture. Such processors require less digital input, reducing the size of the processors and the power they consume. These processors are suitable for embedded systems and smart devices because manufacturers have to manage space in such devices.
Some popular processors used in SoCs include:
- ARM processor models are used in most Android-based mobile phones and some gaming systems like Nintendo and Game Boy Advance.
- IBM’s PowerPC is used in gaming consoles like GameCube, PlayStation 3, and Wii.
2. Memory unit
Since SoCs are small-scale CPUs, they have all the essential components of a regular CPU. Hence, they come with inbuilt memory and storage media. The SoC’s task determines the amount of storage and memory technology it will come with.
The various memory technologies used in SoCs include:
- Flash memory
- Random Access Memory
- Electrically Erasable Read-only Memory
- Read-only memory
The memory unit is not essential in some low-level embedded systems like printers.
3. Terminals/Interfaces
The interfaces are integral to the function of an SoC. Other components of the SoC will interact through terminals located in the processor cores. The interfaces also allow them to access external hardware.
The interfaces on each SoC often depend on market demands. Some of them include USB terminals, HDMI, and Ethernet interfaces. The interfaces also link the SoC to the signal converters, which would help the SoC convert the analogue signals from external sensors.
4. Communications unit
SoCs have many components executing different tasks for the same purpose. These units have to communicate constantly, sending data and information in signals from one unit or module to the other.
Most signal communications in SoCs must be independent of the central systems. Hence, the communication unit must allow direct transmission between external hardware and the SoC memory. There are two major forms of SoC communication models:
- Bus communication: It is the older form of SoC communication, where a central bus is built to connect the components of the SoC. It has the limitations of supporting only a few tens of cores, so engineers can’t use it for large-scale SoC modules.
- Network-on-chip model: This is a novel technology developed in 2010 to alleviate the problem of the bus model. Here, each core has its communication system, with which it interacts with the other cores and the rest of the SoC.
The units listed above constitute the average SoC. You might find alterations in scale, especially in companies with large-scale SoCs for increased system efficiency.