The Raspberry Pi Revolution

The Raspberry Pi is one of the most exciting releases in recent memory. A complete computer, slightly larger than a credit card, sold for a mere $ 35 (or 25 if you choose the model, with no network interface) and it ends up being an open project, which can be used and produced by other manufacturers to create various products.

The project originally emerged as a tool for learning programming languages, especially in third world countries, offering a team cheap enough for each student to receive (already configured with all the necessary development tools) along with other materials and can practice at home.

This explains why the initial model of the Raspberry Pi (dubbed “Model”) has no network interface, since in this scenario the use of network and Internet access is not a necessity, since they are studied based on materials included in the device itself. However, the project ended up growing a lot in addition, attracting the attention of numerous fans interested in using it in different projects, as well as educational organizations and other entities around the world.

The Raspberry Pi is based on a Broadcom BCM2835 SoC, which combines an arm with a processor running at 700 MHz with a VideoCore IV GPU operating at 250 MHz. Despite the clock it seems low compared to desktop GPUs, this is a very powerful GPU, which offers much greater processing power than the PowerVR SGX 535 used in iPhone 4 and other devices, including support for decoding 1080p video via hardware.

To keep costs down, developers have chosen to include a 256MB LPDDR single memory chip, limiting performance and use in desktop applications. The memory is shared between the CPU and the GPU, which by default is only 186 MB of available memory for the system in use.

Although it is not recommended (due to Flash memory write operations) it is possible to use part of the card to exchange memory, expanding the range of applications that can be used.

The power supply is a micro-USB port located next to the memory card. It was chosen to simplify and make the project cheaper, since it allows it to be powered with any cell phone charger (or with a vehicle charger connected to a 12V battery or solar panel) and allows the 5V received to be sent directly to the components that They use 5V, like USB devices plugged into the HDMI port.

Although it has two USB ports (model B) Raspberry Pi is limited in relation to the amount of energy that devices connected to the USB port can provide, since it is itself powered through a USB port. The connectors are designed for devices such as keyboards and mice, USB sticks, and other low-power devices. To use more device wasters, such as external HDs, you must use a self-powered USB hub. Even Wi-Fi cards can be a problem, requiring that the power be capable of supplying at least 700 mA.

The primary video output is an HDMI interface, which supports resolutions up to 1080p. As an option, there is an RCA output, which allows you to use old televisions. The developers decided not to include a VGA output, as this would make it necessary to include an additional driver design that would make it more expensive. The HDMI output is connected directly to the SoC, without the need for additional components. The board also includes a 3.5mm audio jack and headers that allow you to connect a camera or even an LCD Panel with DSI.

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A peculiar detail of the construction of the board is that at first glance the SoC does not seem to be part of it, since it cannot be found anywhere else. To simplify the design of the board, the developers have chosen to use the PoP (package package) system, mounting the memory chip in the SoC and only making it visible:

Unlike a PC, the Raspberry Pi has no BIOS or Setup. Instead, all the hardware-related settings and the boot process are made in a text file located in the root directory of the card, the "config.txt". It encompasses many options on a PC would be available in configuration, including the operating frequency of the processor, which in most cases can be overclocked for up to 900 MHz without major problems. Even overclocked, SoC worry little, allowing you to work smoothly.