Raspberry Pi: Difference between revisions

Revision as of 08:19, 9 June 2013

Revision as of 08:53, 9 June 2013

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# Support for raw [[liquid crystal display|LCD]] panels is available in hardware through the available [[Display Serial Interface|DSI]] connector from the [[Mobile Industry Processor Interface]] (MIPI) Alliance.<ref name="DSI" /> Software support is being planned.

# Supported digital video resolutions are: 640&nbsp;×&nbsp;350 [[Enhanced Graphics Adapter|EGA]]; 640&nbsp;×&nbsp;480 [[Video Graphics Array|VGA]]; 800&nbsp;×&nbsp;600 [[Super video graphics array|SVGA]]; 1024&nbsp;×&nbsp;768 [[XGA]]; 1280×720 [[720p]] [[High-definition television#High-definition display resolutions|HDTV]]; 1280&nbsp;×&nbsp;768 [[Graphic display resolutions#WXGA|WXGA]] Variant; 1280&nbsp;×&nbsp;800 [[Graphic display resolutions#WXGA|WXGA]] Variant; 1280&nbsp;×&nbsp;1024 [[SXGA]]; 1366&nbsp;×&nbsp;768 [[Graphic display resolutions#WXGA|WXGA]] Variant; 1400&nbsp;×&nbsp;1050 [[SXGA+]]; 1600&nbsp;×&nbsp;1200 [[UXGA]]; 1680&nbsp;×&nbsp;1050 [[WXGA+]]; 1920&nbsp;×&nbsp;1080 [[1080p]] [[High-definition television#High-definition display resolutions|HDTV]]; 1920&nbsp;×&nbsp;1200 [[WUXGA]].<ref name="video" /> Also to be supported are the generation of [[576i]] and [[480i]] composite video signals for [[PAL#PAL-B/G/D/K/I|PAL-BGHID]], [[PAL-M]], [[PAL-N]], [[NTSC]] and [[NTSC-J]]<ref name="composite">{{cite web|last=Ozolins |first=Jason |url=http://www.raspberrypi.org/forum/general-discussion/pictures-of-screen-displaying-example-of-rpi-composite-output?value=480i&type=1&include=2&search=1 |title=examples of Raspberry Pi composite output |publisher=Raspberrypi.org |date= |accessdate=2012-06-22}}</ref>

# Originally the on-board USB ports were designed for USB devices using one "unit load" (100 mA) of current. Devices using more than 100&nbsp;mA were incompatible with the Raspberry Pi, and for them a [[USB hub#Power|self-powered USB hub]] was required. However, due to user feedback, the RPF, at the end of August 2012, decided to remove the USB [[polyfuse]]s which largely caused this behaviour. However, the maximum current that can be delivered to a USB port on these modified boards is still limited by the capabilities of the power supply used, and the 1.1&nbsp;A main polyfuse. Spontaneous rebooting and/or crashing caused by hot plugging certain USB devices was introduced as a result of this change, which further reduced the standards compliance of the Raspberry Pi's USB implementation.<ref>{{cite web|url=http://www.raspberrypi.org/phpBB3/viewtopic.php?f=24&t=5830 |title=Design flaw? Polyfuses for USB current limiting |publisher=Raspberrypi.org |date= |accessdate=2012-06-22}}</ref>

# Newer versions of the firmware contain the option to choose between five overclock ("turbo") presets that when turned on try to get the most performance out of the SoC without impairing the lifetime of the Pi. This is done by monitoring the core temperature of the chip, and the CPU load, and dynamically adjusting clock speeds and the core voltage. So when there is a low demand on the CPU, or it is getting too hot, the performance is throttled down, but if the CPU has much to do, and the chip's temperature allows it, performance is temporarily increased, with clock speeds up to 1&nbsp;GHz, depending on the individual board, and on which of the "turbo" settings is used. The five settings currently are:

## "None"; 700&nbsp;MHz ARM, 250&nbsp;MHz core, 400&nbsp;MHz SDRAM, 0 overvolt,

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## "Medium" 900&nbsp;MHz ARM, 250&nbsp;MHz core, 450&nbsp;MHz SDRAM, 2 overvolt,

## "High"; 950&nbsp;MHz ARM, 250&nbsp;MHz core, 450&nbsp;MHz SDRAM, 6 overvolt,

## "Turbo"; 1000&nbsp;MHz ARM, 500&nbsp;MHz core, 600&nbsp;MHz SDRAM, 6 overvolt<ref name="Turbo mode"/><ref name="turbosgithub">{{cite web|url=https://github.com/asb/raspi-config/blob/master/raspi-config |title=asb/raspi-config on Github |publisher=asb |accessdate=2012-12-13}}</ref>

In the highest ("turbo") preset the SDRAM clock was originally 500 MHz, but this was later changed from to 600 Mhz because 500 MHZ sometimes causes SD card corruption. Simultaneously in "High" mode the core clock speed was lowered from 450 to 250 MHz.

# The five overclock ("turbo") presets were changed because overclocking the core causes SD card corruption, apparently due to bugs in the BCM2835 SoC. They originally were<ref name=overclock>[https://github.com/asb/raspi-config/commit/c5e1966418922862b2a84559c567c35e6a1c4c28 add overclocking options · c5e1966 · asb/raspi-config · GitHub]</ref>:

## "None"; 700&nbsp;MHz ARM, 250&nbsp;MHz core, 400&nbsp;MHz SDRAM, 0 overvolt,

## "Modest"; 800&nbsp;MHz ARM, 300&nbsp;MHz core, 400&nbsp;MHz SDRAM, 0 overvolt,

## "Medium" 900&nbsp;MHz ARM, 333&nbsp;MHz core, 450&nbsp;MHz SDRAM, 2 overvolt,

## "High"; 950&nbsp;MHz ARM, 450&nbsp;MHz core, 450&nbsp;MHz SDRAM, 6 overvolt,

## "Turbo"; 1000&nbsp;MHz ARM, 500&nbsp;MHz core, 500&nbsp;MHz SDRAM, 6 overvolt

== Software ==