RPi 常见问题解答

Raspberry Pi 是什么？
The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. It’s a capable little PC which can be used for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. We want to see it being used by kids all over the world to learn programming.

我可以购买 Raspberry Pi 的股份吗？
We’re a charity, so you can’t buy shares in the company. If you want to support us, we’d love you to buy one. We’ll also be offering a package where you can do a buy-one-give-one purchase, and we’ll be accepting donations too once we start shipping.

Where can I buy one?
The Raspi is available to purchase through Premier Farnell/Element 14 and RS Components. Chinese customers might enquire at Egoman Technology

How many can I buy in one go?
For the first batch we limited orders to one per person. This was to prevent eBay scalping (to some extent – we also auctioned some boards ourselves to try to make sure there’s no market for scalpers), and ensure that as many different individuals as possible got their Raspberry Pi!

How much does it cost?
The Model A costs $25 and the Model B $35, plus local taxes and shipping.

How can I pay for it?
The distributors accept most major cards, PayPal, and offline payments.

What will I get when I buy one?
A Raspberry Pi. Leads, a power supply, case or SD cards are not included but can be purchased from any of the Raspberry Pi vendors: Premier Farnell/Element 14 and RS Components. You can build an operating system on your own SD card or buy one preloaded with Raspian "wheezy" from the same source.

Why is the price in US Dollars? You’re a UK company!
The components we buy are priced in dollars, and we negotiate manufacturing in dollars. Because currency markets are so volatile at the moment, we price the final board in dollars too, so we don’t have to keep changing the price.

Will there be a buy-one-give-one program?
Yes. We plan to implement a program of this sort, but you can also just buy one if you prefer.

Will the device be available internationally?
Premier Farnell/Element 14 and RS Components distribute and ship world-wide via subsidiaries and partners in virtually every country. There have been some problems with information about pricing and availability being fully shared among some countries' local offices, but, they are being worked out with the primary distributors and should be resolved by mid-March 2012.

How much will it cost to ship to [country X]?
Premier Farnell/Element 14 and RS Components and their subsidiaries/partners will convey this information before orders are charged, and these costs may vary from country to country, which the Foundation cannot control.

Will there be a minimum order quantity?
The minimum order quantity is one unit. The maximum order size restriction has been lifted.

Do you accept pre-orders?
Pre-orders are now being taken by Premier Farnell/Element 14 and RS Components

I want to be a Raspberry Pi reseller.
We are not taking requests for people to be resellers at the moment. However, nothing stops your buying devices from the distributors and reselling them with accessories.

Can I join the mailing list?
You certainly can. Head to the home page, and you’ll see a form at the top right you can fill in. People who are signed up will get an e-mail as soon as we have confirmed a release date.

What’s the difference between Model A and Model B?
Model A has 256 MB of RAM, HDMI, one USB port and no Ethernet (network connection). Two revisions of the Model B exist. The first (now referred to as revision 1) has 256 MB RAM, HDMI, two USB ports and a 100 Mbits/sec Ethernet port. Model B revision 2 has 512MB RAM with the same ports.

What are the dimensions of the Raspberry Pi?
The Raspberry Pi measures 85.60mm x 53.98mm x 17mm, with a little overlap for the SD card and connectors which project over the edges. It weighs 45g.

What SoC are you using?
The SoC is a Broadcom BCM2835. This contains an ARM1176JZFS, with floating point, running at 700Mhz, and a Videocore IV GPU. The GPU is capable of BluRay quality playback, using H.264 at 40 Mbits/s. It has a fast 3D core accessed using the supplied OpenGL ES 2.0 and OpenVG libraries.

Why did you select the ARM11?
Cost and performance.

How powerful is it?
The GPU provides Open GL ES 2.0, hardware-accelerated OpenVG, and 1080p30 H.264 high-profile decode.

The GPU is capable of 1 Gpixel/s, 1.5 Gtexel/s or 24 GFLOPs of general purpose compute and features a bunch of texture filtering and DMA infrastructure.

That is, graphics capabilities are roughly equivalent to Xbox 1 level of performance. Overall real-world performance is something like a 300MHz Pentium II, only with much, much swankier graphics.

Will it overclock?
There’s a little overclocking headroom – most devices will run happily at 800MHz. There’s no BIOS per se, but we do support booting bare metal code, so something could be done.

Will it blend?
Yes. We have conducted extensive virtual simulations. No Raspberry Pis were harmed in the testing.

How does it boot?
You have to boot from SD but a USB HD can “take over” after the initial boot. You cannot boot without an SD card.

Where’s the on / off switch?
To switch on: just plug it in!

To switch off: remove power.

Or if you really want a switch, you can get a Pi Supply Switch

Why is there no real time clock (RTC)?
The expectation is that non-network connected units will have their clocks updated manually at startup. Adding an RTC is surprisingly expensive, once you’ve factored in batteries, area and componentry and would have pushed us above our target price. You can add one yourself using the GPIO pins if you’re after an interesting electronics project.

Will you sell a self-assembly kit?
No. It would be too expensive for us to provide kits alongside finished boards, which would mean introducing another step in manufacturing; and a kit would be impossible to hand solder. We use special equipment (robots!) to solder on the BGA package and other tiny components.

Can I add extra memory?
No. The RAM is a POP package on top of the SoC, so it’s not removable or swappable.

What hardware documentation will be available?
Broadcom don’t release a full datasheet for the BCM2835, which is the chip at the heart of the Raspberry Pi. We have released a datasheet for the SoC which covers the hardware exposed on the Raspi board e.g. the GPIOs. We also have released a board schematic.

But I want documentation for &lt;hardware X&gt;!
Other documentation may be released in future but this will be at the Foundation’s discretion.

But I demand the documentation for the chip. Give it to me!
To get the full SoC documentation you would need to sign an NDA with Broadcom, who make the chip and sell it to us. But you would also need to provide a business model and estimate of how many chips you are going to sell.

Why doesn’t the Raspberry Pi include &lt;insert name&gt; piece of hardware or &lt;insert name&gt; sort of port?
Our main function is a charitable one – we’re trying to build the cheapest possible computer that provides a certain basic level of functionality, and keeping the price low means we’ve had to make hard decisions about what hardware and interfaces to include.

Can you test it to make sure that it is suitable for &lt;X&gt;?
If you want to use it for something that we haven’t tested, and that it’s not intended for (i.e. anything but the educational work we’re planning for it), then that development work is up to you.

How do I connect a mouse and keyboard?
Model A has one USB port and Model B has two. Beyond this, mice, keyboards, network adapters and external storage will all connect via a USB hub.

Will it have a case?
Not for the first batch. We’ll be making and selling cases by the summer; you'll be able to buy a unit with or without a case, or a case on its own. The education release later in 2012 will have a case by default. There are lots of homebrew case discussions on the forum.

Will it fit in an Altoids tin?
Doesn’t quite work, I’m afraid – because we don’t round off the edges of the board, it’s a little too big to fit the tin.

What display can I use?
There is composite and HDMI out on the board, so you can hook it up to an old analog TV, to a digital TV or to a DVI monitor (using a cheap adapter for the DVI). There is no VGA support, but adaptors are available, although these are relatively expensive.

Why is there no VGA support?
The chip specifically supports HDMI. VGA is considered to be an end-of-life technology, so supporting it doesn’t fit with our plans at the moment.

Is there a GPU binary?
Yes. The GPU binary also contains the first stage bootloader.

Can I add a touchscreen?
We haven’t experimented with any touchscreens yet, but there’s no electronic reason why it shouldn’t work. There’s lots of discussion about this on the forums. The main issue people are encountering seems to be one of cost; touchscreens are very pricey!

What is the usable temperature range?
The Raspberry Pi is built from commercial chips which are qualified to different temperature ranges; the LAN9512 is specified by the manufacturers being qualified from 0°C to 70°C, while the AP is qualified from -40°C to 85°C. You may well find that the board will work outside those temperatures, but we’re not qualifying the board itself to these extremes.

Is sound over HDMI supported?
Yes.

What about standard audio in and out?
There’s a standard 3.5mm jack for audio out. You can add any supported USB microphone for audio in.

What are the power requirements?
The device is powered by 5v micro USB. You can read more about it here. Power supplies will be available at launch.

Can I run power Raspberry Pi from batteries as well as from a wall socket?
Yes. The Model A should run well off 4 x AA cells.

Is power over Ethernet (PoE) possible?
Not in the base device, but it’s been a very commonly requested feature, so we’re examining options for later releases.

What operating system (OS) does it use?
It is capable of running several different operating systems. As of July 2012, the Foundation recommmends Raspbian "Wheezy" for first-time users. It’s straightforward to replace the root partition on the SD card with another ARM Linux distro if you want to use something else. The OS is stored on the SD card.

Does it have an official programming language?
By default, we’ll be supporting Python as the educational language.

Any language which will compile for ARMv6 can be used with the Raspberry Pi, though; so you’re not limited to using Python.

Will it run WINE (or Windows, or other x86 software)?
No.

What Linux distros will be supported at launch?
Fedora, Debian and ArchLinux will be supported from the start. We hope to see support from other distros later (because of issues with newer releases of Ubuntu and the ARM processor we are using, Ubuntu can’t commit to supporting Raspberry Pi at the moment). You will be able to download distro images from us as soon as the Raspberry Pi is released, and we will also be selling pre-loaded SD cards shortly after release.

Will it run Android?
If someone in the community can port a version of Android to work with 256MB of RAM, then it’ll run on the Raspberry Pi.

Will it run &lt;insert name of program here&gt;?
In general, you need to look to see whether the program you want can be compiled for the ARMv6 architecture. In most cases the answer will be yes. Specific programs are discussed on our forum, so you might want to look there for an answer.

Will it run the new Windows RT?
We are not partners with Microsoft, and their support would be required for porting Windows 8.

SD 卡和存储
We have tried cards up to 32GB and most cards seem to work OK. The Wiki has more information about which makes and models work best. You can also attach a USB flash memory stick or USB hard drive for storage.

What happens if I brick the device?
You can restore the device by reflashing the SD card.

Does the device support networking? Is there Wi-Fi?
The Model B version of the device includes 10/100 Mbits/second wired Ethernet. There is no Ethernet on the Model A version (which we expect to be taken up mostly by the education market), but Wi-Fi will be available via a standard USB dongle.

Will there be a WiFi option?
Not in the first version, though you can add a dongle. ARM Linux WiFi support can be a bit patchy; there’s a list of tested dongles on the wiki.

Why no Gigabit Ethernet?
The Ethernet is driven via USB 2.0, so the upstream bandwidth would not support Gigabit.

Does the device have support for any form of netbooting or Pxe?
No. However, it’s such a low-power device that we expect it to be left on much of the time!

How do you connect more than two USB devices?
Use a hub to increase the number of ports. Some keyboards have hubs built in which would work well.

What educational material will be available?
We’re working with partners to get software materials developed, as well as with the open source community. Computing at School is writing a user guide and programming manual, we’re aware of a few books being planned and written around the Raspberry Pi, and others have already started to produce some excellent tutorials including video. We’re also working with partners to use it as a teaching platform for other subjects, including languages, math, and so on.

Once we launch, we hope that the community will help organizations like Computing at School put together teaching material such as lesson plans and resources and push this into schools. In due course, the foundation hopes to provide a system of prizes to give young people something to work towards.

There’s lots of discussion of educational uses and resources in our forums – come and have a chat!

术语表
BGA: Ball Grid Array. A type of surface mount packaging for electronics.

SoC: System on Chip. A computer on a single integrated circuit.

GPIO: General Purpose Input/Output. Pins that can be programmed to do stuff.

GPU: Graphics Processing Unit. The hardware that handles 3-D graphics in scientific notation (floating point) math.

Distro: a specific package (“flavor”) of Linux and associated software.

Brick: to accidentally render a device inoperative by making changes to software or firmware.

Pxe: Preboot execution environment. A way to get a device to boot via the network.

PoE: Power over Ethernet. Powering a device via an Ethernet cable.