====== IoT Hardware Overview ======
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IoT hardware infrastructure is mainly inherited from the embedded systems of the SoC type for Edge class IoT devices and from PCs for Fog class. As IoT devices are by their nature network-enabled, many of the existing embedded platforms evolved towards network-enabled solutions, sometimes indirectly through delivering network communication module (wired or wireless) as an external device yet integrated on the development board (e.g. Arduino Uno with Ethernet Networking shield, GSM shield, etc.), sometimes a new system, integrating networking capabilities in one SoC (e.g. Espressif SoCs). More advanced devices that require OS to operate preliminarily benefited from externally connected peripheral network interfaces via standard wired ports like USB (e.g. early versions of the Raspberry Pi, where WiFi card was delivered as USB stick), currently, usually integrate most of the network interfaces in a single board (e.g. RPi 4, including Ethernet, WiFi and Bluetooth). Still, in the case of the Fog class devices, those are separate chips from the CPU, and they communicate over, e.g., PCI or USB protocol.

A microcontroller with network capabilities is the key, but it is not the only element forming an IoT node device. Additional elements, including sensors and actuators, are needed to stay in touch with the environment.
It is important to emphasise that only hardware components carrying CE marking are appropriate in Europe. This is important in providing human safety for HVAC, DC modules and other electrical devices, while EMC/ETSI regulatory compliance applies to radio devices.
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In the following chapters, there is a description of the families of popular microcontrollers, sensors and actuators:
  * [[en:iot-open:hardware2:microcontrollers]],
  * [[en:iot-open:hardware2:sensors]],
  * [[en:iot-open:hardware2:actuators]].

Finally, in the last sub-chapter, there is an introduction to the powering of IoT devices:
  * [[en:iot-open:hardware2:powering]].
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