Raspberry Pi_Eng_02.6.2 Power Constraints of USB Port

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2.6.2 Power Constraints of USB Port

The required power level of USB devices is defined in 100mA increments from 100mA to 500mA. When a USB device is first connected to a computer, it informs the USB Host of its required power requirements. In theory, the actual power used by a USB device should not exceed its self-defined limits.

The USB ports on the Raspberry Pi are designed to withstand loads of at least 100mA each, which is sufficient to operate low-power devices such as mouse and keyboards. However, devices such as Wi-Fi adapter, USB hard drive, and USB pen drive may consume much more power depending on the USB device. Thus, if Raspberry Pi’s own power is insufficient, it is good to use an external USB hub with separate power supply. Of course you can connect a USB device that uses 500mA power directly to the USB port of Raspberry Pi, and operate the USB device by supplying enough power to the Raspberry Pi, but if the power is insufficient, it is difficult to guarantee reliable operation.

Raspberry Pi_Eng_02.6.1 USB Port by Model

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2.6 USB port

2.6.1 USB Port by Model

Nowadays, many peripherals such as a keyboard, a mouse, and a camera are all connected to the computer main body through USB.

The Raspberry Pi system also provides a USB port that supports USB 2.0. As Linux already have drivers installed for most peripherals, so you can plug your peripherals into a Raspberry Pi system for immediate use.

Raspberry Pi_Eng_02.5.4 3.5mm Audio Jack and Composite Video

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2.5.4 3.5mm Audio Jack and Composite Video

The Raspberry Pi offers a 3.5 m audio jack to support stereo. When using HDMI output from Raspberry Pi, audio output can also be transmitted to the HDMI port together with video output, so that external device can play video and audio at once. However, if separate audio output such as a speaker and a headphone is required, audio may be outputted separately through an audio jack.

Raspberry Pi_Eng_02.5.3 DSI Display Port

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2.5.3 DSI Display Port

Raspberry Pi supports DSI (Digital Serial Interface) connection to support TFT-LCD display. When connecting the device, you can connect it to the DSI display port protected by a plastic layer over the SD card slot on the top of the printed circuit board.

In addition, in order to use Raspberry Pi with a touch screen without a keyboard or mouse, touch-screen drivers that support 10-finger touch and on-screen keyboards is integrated in the latest version of the Raspbian operating system.

Raspberry Pi_Eng_02.5.2 CSI Camera Interface

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2.5.2 CSI Camera Interface

Raspberry Pi can use a regular USB camera, but it has a device for Pi-only camera. You can connect a dedicated camera with a short ribbon cable to the CSI camera port on the board. The CSI port is connected to the ISP (Image System Pipeline) in SoC of Raspberry Pi. ISP processes the incoming camera data and converts it into image or video. Using this camera, we use 250mA of current.

Raspberry Pi_Eng_02.5.1 HDMI Video Port

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2.5.1 HDMI Video Port

In the past, VGA/DVI monitors were widely used video devices, but most modern monitors support High Definition Multimedia Interface (HDMI), which displays high-resolution images. The Raspberry Pi is designed to use Full HDMI output with full HD 1920×1080 resolution as the primary video output, and comes with an HDMI port to support it as a standard.

Raspberry Pi_Eng_02.4.2 Current Consumption by Device

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2.4.2 Current Consumption by Device

Raspberry Pi has a limited current that can be supplied to the entire USB port. Raspberry Pi 1 model A, A+, B can supply up to 500mA of current to all USB devices. Raspberry Pi model 1 model B+ and Raspberry Pi 2 model B can supply up to 600mA/1.2A current to all USB devices, which can be switched according to the firmware setting. The Raspberry Pi 3 model B has been improved to provide up to 1.2 A current to the USB port, allowing you to connect more USB devices which requires much current directly to Raspberry Pi compared to the previous models.

Raspberry Pi_Eng_02.4.1 Micro USB Power Supply Port

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2.4 Power Supply

2.4.1 Micro USB Power Supply Port

Raspberry Pi supports Micro USB socket to power the system. Micro USB sockets are a common standard for charging mobile phones and mobile devices.

The power supplied to the system is using a 5.1V DC power supply. How much current is needed in Raspberry Pi depends on the type of Raspberry Pi model and number of peripherals connected to Raspberry Pi.

Raspberry Pi_Eng_02.2 SoC, CPU and Memory

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2.2 SoC, CPU and Memory

● System on a Chip(SoC)

Raspberry Pi is a System on a Chip (SoC) type computer. System on a Chip (SoC) refers to the way in which all electronic components required for computer operation are concentrated on one chip. In this method, the CPU, GPU, USB controller, RAM, Northbridge, Southbridge, and other components are compressed and bundled together on one chip without installing separate chips.

Raspberry Pi_Eng_02.1.2 Characteristics Comparison of Raspberry Pi Model

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2.1.2 Characteristics Comparison of Raspberry Pi Model

● Characteristics of Raspberry Pi 1 model A and Raspberry Pi 1 model B

device

Raspberry Pi 1 model A/A+

Raspberry Pi 1 model B/B+

SoC

Broadcom BCM2835

Broadcom BCM2835

CPU

700MHz Single-Core

ARM 1176JZFS

700MHz Single-Core

ARM 1176JZFS