3.4.2 External Mass Storage Device
Raspberry Pi can use an SD card as a storage device, but SD cards usually have a limited storage capacity, so if you need to store a large volume of data, you need an external storage device. If you want to use such an external storage device, you need to connect it to a USB port.
.4.1 SD Card
As Raspberry Pi is designed to install operation system on the SD card, SD card is essential.
When purchasing an SD card, the capacity should be at least 4 GB, and it is recommended t use usually 8 GB or more. In some cases, you might want to use a 16 GB or 32 GB SD card if you want to install a lot of programs or to save a lot of data on your system.
3.3 Heat Sink
Raspberry Pi adopts the ARM processor. The power consumption of these CPU, GPU, etc is very low, and there is almost no heat in normal operating environment, so Raspberry Pi is designed from the beginning so that it does not need extra cooling function like cooling fan.
3.2 Body Case
The size of Raspberry Pi body is very small. The main board is provided with four holes for fixing the main board, so that it can be fixed to another machine or equipment. However, since there is no part to protect the board itself, it can be damaged from external contact or impact. Therefore, we need a case that physically protects the board and protects the board from dust and pollutants from the outside.
.10 External Interface
Raspberry Pi can communicate with and control devices outside the system through a bidirectional interface with external devices. It can receive input or output through an external device, or adjust an external device. A key device for this is the GPIO (General Purpose Input Output) port. Here, I will briefly mention the preparations required to use this GPIO. For details, refer to [Chapter 25 External Interface]:
3.1 Selection of Raspberry Pi Model
When purchasing Raspberry Pi, you should clarify the purpose of use. If you want to use it only for a limited purpose, you can use a lower model that has a relatively low processing power. However, if you want to use it as a general purpose just like general PC, you will have to use the latest upper model that have various advanced features and high level processing.
Chapter 3 Buying & Installing Device/Part
Chapter’s Main Topics
Here this chapter will find out what devices are needed to operate Raspberry Pi and how to connect them to Raspberry Pi.
It includes descriptions on the following topics:
■ Selection of Raspberry Pi model
■ Body case and heat sink
■ Storage device
■ Power supply device
■ Network device
■ Input device
■ Video output
■ Camera
■ External interface device
2.4.2 장치별 전류 소비
Raspberry Pi에서 전체 USB port에 공급할 수 있는 전류에 제한이 있다. Raspberry Pi 1 model A, A+, B는 전체 USB 기기에 최대 500mA 전류를 공급할 수 있다. Raspberry Pi model 1 model B+ 와 Raspberry Pi 2 model B에서는 전체 USB 기기에 최대 전환 가능한 600mA/1.2A 의 전류를 공급할 수 있는데, firmware 설정에 따라 서로 전환이 가능하다. Raspberry Pi 3 model B에서는 USB port에 최대 1.2 Amp까지 전류를 공급할 수 있도록 개선되어 이전 model에 비해서 많은 전류가 필요한 USB 장치를 더 많이 Pi에 직접 연결하여 사용할 수 있게 되었다.
2.4.1 Micro USB power supply port
Raspberry Pi에서는 시스템에 전원을 공급하기 위해서 Micro USB socket를 지원하고 있다. Micro USB socket은 보통 휴대폰이나 모바일 기기에서 충전용으로 많이 사용되는 표준이다.
시스템에 공급되는 전원은 5.1V DC 전원을 사용하고 있다. Raspberry Pi에서 얼마나 많은 전류를 필요로 하는가는 Raspberry Pi의 model과 Raspberry Pi에 연결되어 있는 주변기기의 종류와 개수에 달려 있다.
2.2 SoC, CPU 및 memory
● System on a Chip(SoC)
Raspberry Pi는 System on a Chip (SoC) 형태의 컴퓨터이다. System on a Chip (SoC)은 컴퓨터 실행에 필요한 모든 전자부품을 하나의 chip에 집중하여 설치하는 방식을 말한다. 이 방식에는 CPU, GPU, USB controller, RAM, northbridge, southbridge, 기타의 부품별로 별도의 chip을 설치하지 않고 압축하여 하나로 묶어서 장착하는 방식을 취한다.