Raspberry Pi
Series of low-cost single-board computers used for educational purposes and embedded systems / From Wikipedia, the free encyclopedia
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Raspberry Pi (/paɪ/) is a series of small single-board computers (SBCs) developed in the United Kingdom by the Raspberry Pi Foundation in association with Broadcom. Since 2013, Raspberry Pi devices have been developed and supported by a subsidiary of the Raspberry Pi Foundation, now named Raspberry Pi Ltd.[3] The Raspberry Pi project originally leaned toward the promotion of teaching basic computer science in schools.[4][5][6] The original model became more popular than anticipated,[7] selling outside its target market for diverse uses such as robotics, home and industrial automation, and by computer and electronic hobbyists, because of its low cost, modularity, open design, and its adoption of the HDMI and USB standards.
Also known as | RPi, Raspi |
---|---|
Type | Single-board computer |
Release date | 29 February 2012; 12 years ago (2012-02-29) |
Operating system | Linux (incl Raspberry Pi OS) FreeBSD NetBSD OpenBSD Plan 9 RISC OS Windows 10 Windows 10 IoT Core[1] QNX and OS-less Embedded RTL's[clarification needed]. |
Storage | MicroSDXC slot, USB mass storage device for booting[2] |
Website | www |
After the release of the second board type, the Raspberry Pi Foundation set up a new entity, named Raspberry Pi (Trading) Ltd, and installed Eben Upton as CEO, with the responsibility for developing their computers.[8] The Foundation was rededicated as an educational charity for promoting the teaching of basic computer science in schools and developing countries. Most Raspberry Pis are made in a Sony factory in Pencoed, Wales,[9] while others are made in China and Japan.[10][11]
In 2015, the Raspberry Pi surpassed the ZX Spectrum in unit sales, becoming the best-selling British computer.[12]
In 2021, Raspberry Pi (Trading) Ltd changed its name to Raspberry Pi Ltd.[13]
There are three series of Raspberry Pi, and several generations of each have been released. Raspberry Pi SBCs feature a Broadcom system on a chip (SoC) with an integrated ARM-compatible central processing unit (CPU) and on-chip graphics processing unit (GPU), while Raspberry Pi Pico has a RP2040 system on chip with an integrated ARM-compatible central processing unit (CPU).
Raspberry Pi
- The first-generation Raspberry Pi Model B was released in February 2012, followed by the simpler and cheaper Model A.
- Raspberry Pi Model B+, an improved design, was released in 2014. These first-generation boards feature ARM11 processors, are approximately credit-card sized, and represent the standard mainline form factor. Improved A+ and B models were released within a year. A "Compute Module" was released in April 2014 for embedded applications.
- The Raspberry Pi 2 was released in February 2015 and initially featured a 900 MHz 32-bit quad-core ARM Cortex-A7 processor with 1 GB RAM. Revision 1.2 features a 900 MHz 64-bit quad-core ARM Cortex-A53 processor (the same as that in the Raspberry Pi 3 Model B, but underclocked to 900 MHz).[14]
- The Raspberry Pi 3 Model B was released in February 2016 with a 1.2 GHz 64-bit quad core ARM Cortex-A53 processor, on-board 802.11n Wi-Fi, Bluetooth and USB boot capabilities.[15]
- The Raspberry Pi 3 Model B+ was launched on Pi Day 2018 with a faster 1.4 GHz processor, a three-times faster Gigabit Ethernet (throughput limited to ca. 300 Mbit/s by the internal USB 2.0 connection), and 2.4 / 5 GHz dual-band 802.11ac Wi-Fi (100 Mbit/s).[16] Other features are Power over Ethernet (PoE) (with the add-on PoE HAT), USB boot and network boot (an SD card is no longer required).
- The Raspberry Pi 3 Model A+ was launched in November 2018 as a similar board to the first Model A. It has a 1.4 GHz 64-bit quad-core processor, with 2.4 GHz dual-band and 5GHz wireless LAN & Bluetooth 4.2. It also has a 40-pin GPIO header, 512 MB of DDR2 RAM, is powered by 5V of DC power via microUSB. A full-size HDMI port is used for connectivity, and two USB 2.0 ports are on the board.
- The Raspberry Pi 4 Model B was released in June 2019[17] with a 1.5 GHz 64-bit quad core ARM Cortex-A72 processor, on-board 802.11ac Wi-Fi, Bluetooth 5, full gigabit Ethernet (throughput not limited), two USB 2.0 ports, two USB 3.0 ports, 1, 2, 4, or 8 GB of RAM, and dual-monitor support via a pair of micro HDMI (HDMI Type D) ports for up to 4K resolution. The version with 1 GB RAM has been abandoned and the prices of the 2 GB version have been reduced. The 8 GB version has a revised circuit board. The Raspberry Pi 4 is also powered via a USB-C port, enabling additional power to be provided to downstream peripherals, when used with an appropriate PSU. But the Pi can only be operated with 5 volts and not 9 or 12 volts like other mini computers of this class. The initial Raspberry Pi 4 board had a design flaw where third-party e-marked USB cables, such as those used on MacBooks, incorrectly identify it and refuse to provide power.[18][19] Tom's Hardware tested 14 different cables and found that 11 of them turned on and powered the Pi without issue.[20] The design flaw was fixed in revision 1.2 of the board, released in late 2019.[21] In mid-2021, Pi 4 B models appeared with the improved Broadcom BCM2711C0. The manufacturer is now using this chip for the Pi 4 B and Pi 400. However, the clock frequency of the Pi 4 B was not increased in the factory.
- The Raspberry Pi 400 was released in November 2020. A modern example of a keyboard computer, it features 4 GB of LPDDR4 RAM on a custom board derived from the existing Raspberry Pi 4 combined with a keyboard in a single case. The case was derived from that of the Raspberry Pi Keyboard.[22] A robust cooling solution (i.e. a broad metal plate) and an upgraded switched-mode power supply[23] allow the Raspberry Pi 400's Broadcom BCM2711C0 processor to be clocked at 1.8 GHz, which is 20% faster than the Raspberry Pi 4 upon which it is based.[24]
- The Raspberry Pi 5 was announced on September 28, 2023.[25] Improvements in hardware and software reportedly make the Pi 5 more than twice as powerful as the Pi 4.[26] It comes with an I/O-controller designed in-house, a power button, and an RTC chip, among other things. The RTC chip needs a battery, which can be purchased, but it saves a Pi user the cost of the chip. Unlike the Pi 4, it was released with either 4 or 8 GB of RAM. The 4 GB model costs US$60 and the 8 GB model costs US$80. An important thing to note is that it lacks a 3.5 mm audio/video jack. Users can use Bluetooth, HDMI, USB audio or an Audio HAT if they want to hear sound out of the Pi 5.
Raspberry Pi Zero
- The Raspberry Pi Zero with smaller size and reduced input/output (I/O) and general-purpose input/output (GPIO) capabilities was released in November 2015 for US$5.
- The Raspberry Pi Zero v1.3 was released in May 2016, which added a camera connector.[27]
- The Raspberry Pi Zero W was launched in February 2017, a version of the Zero with Wi-Fi and Bluetooth capabilities, for US$10.[28][29]
- The Raspberry Pi Zero WH was launched in January 2018, a version of the Zero W with pre-soldered GPIO headers.[30]
- The Raspberry Pi Zero 2 W was launched in October 2021, a version of the Zero W with a system in a package (SiP) designed by Raspberry Pi and based on the Raspberry Pi 3.[31] In contrast to the older Zero models, the Pi Zero 2 W is 64-bit capable. The price is around US$15.
Raspberry Pi Pico
- Raspberry Pi Pico was released in January 2021 with a retail price of $4.[32] It was Raspberry Pi's first board based upon a single microcontroller chip; the RP2040, which was designed by Raspberry Pi in the UK.[33] The Pico has 264 KB of RAM and 2 MB of flash memory. It is programmable in C, C++, Assembly, MicroPython, CircuitPython and Rust. Raspberry Pi has partnered with Adafruit, Pimoroni, Arduino and SparkFun to build accessories for Raspberry Pi Pico and variety of other boards using RP2040 Silicon Platform.[34] Rather than perform the role of general purpose computer (like the others in the range) it is designed for physical computing, similar in concept to an Arduino.[35]
- The Raspberry Pi Pico W was launched in June 2022, a version of the Pico with 802.11n Wi-Fi capability, for US$6. The CYW43439 wireless chip in the Pico W also supports Bluetooth, but the capability was not enabled at launch.[36]
Model comparison
Family | Model | SoC | Memory | Form Factor | Ethernet | Wireless | GPIO | Released | Discontinued |
---|---|---|---|---|---|---|---|---|---|
Raspberry Pi | B | BCM2835 | 256 MB | Standard[lower-alpha 1] | Yes | No | 26-pin | 2012 | Yes |
512 MB | 2012[37] | ||||||||
A | 256 MB | No | 2013 | ||||||
B+ | 512 MB | Yes | 40-pin | 2014 | No | ||||
A+ | 256 MB | Compact[lower-alpha 2] | No | Yes | |||||
512 MB | No | ||||||||
Raspberry Pi 2 | B | BCM2836 / 7 | 1 GB | Standard[lower-alpha 1] | Yes | No | 2015 | ||
Raspberry Pi Zero | BCM2835 | 512 MB | Ultra-compact[lower-alpha 3] | No | No | ||||
W / WH | Yes | 2017 | |||||||
2 W | BCM2710A1[lower-alpha 4][38] | 2021 | |||||||
Raspberry Pi 3 | B | BCM2837A0 / B0 | 1 GB | Standard[lower-alpha 1] | Yes | Yes | 2016 | ||
A+ | BCM2837B0 | 512 MB | Compact[lower-alpha 2] | No | Yes[lower-alpha 5] | 2018 | |||
B+ | 1 GB | Standard[lower-alpha 1] | Yes[lower-alpha 6] | 2018 | |||||
Raspberry Pi 4 | B | BCM2711B0 / C0[39] | 1 GB | Standard[lower-alpha 1] | Yes[lower-alpha 7] | Yes[lower-alpha 5] | 2019[40] | Yes (2020)[41] | |
2021[42] | No | ||||||||
2 GB | 2019[40] | ||||||||
4 GB | |||||||||
8 GB | 2020 | ||||||||
400 | 4 GB | Keyboard | |||||||
Raspberry Pi Pico | RP2040 | 264 KB | Pico[lower-alpha 8] | No | No | 2021 | |||
W | Yes[lower-alpha 9] | 2022 | |||||||
Raspberry Pi 5[43] | BCM2712 | 4 GB | Standard[lower-alpha 1] | Yes[lower-alpha 7] | Yes[lower-alpha 5] | 2023 | |||
8 GB |
- Custom Raspberry Pi SiP RP3A0
- Gigabit Ethernet; Throughput limited to ca. 300 Mbit/s by the internal USB 2.0 connection
As of 4 May 2021, Raspberry Pi is committed to manufacture most Pi models until at least January 2026. Even the 1 GB Pi 4B can still be specially-ordered.[44]
This section needs additional citations for verification. (November 2020) |
The Raspberry Pi hardware has evolved through several versions that feature variations in the type of the central processing unit, amount of memory capacity, networking support, and peripheral-device support.
This block diagram describes models B, B+, A and A+. The Pi Zero models are similar, but lack the Ethernet and USB hub components. The Ethernet adapter is internally connected to an additional USB port. In Model A, A+, and the Pi Zero, the USB port is connected directly to the system on a chip (SoC). On the Pi 1 Model B+ and later models the USB/Ethernet chip contains a five-port USB hub, of which four ports are available, while the Pi 1 Model B only provides two. On the Pi Zero, the USB port is also connected directly to the SoC, but it uses a micro USB (OTG) port. Unlike all other Pi models, the 40 pin GPIO connector is omitted on the Pi Zero, with solderable through-holes only in the pin locations. The Pi Zero WH remedies this.
Processor speed ranges from 700 MHz to 1.4 GHz for the Pi 3 Model B+ or 1.5 GHz for the Pi 4; on-board memory ranges from 256 MB to 8 GB random-access memory (RAM), with only the Raspberry Pi 4 and the Raspberry Pi 5 having more than 1 GB. Secure Digital (SD) cards in MicroSDHC form factor (SDHC on early models) are used to store the operating system and program memory, however some models also come with onboard eMMC storage[45] and the Raspberry Pi 4 can also make use of USB-attached SSD storage for its operating system.[46] The boards have one to five USB ports. For video output, HDMI and composite video are supported, with a standard 3.5 mm tip-ring-sleeve jack carrying mono audio together with composite video. Lower-level output is provided by a number of GPIO pins, which support common protocols like I²C. The B-models have an 8P8C Ethernet port and the Pi 3, Pi 4 and Pi Zero W have on-board Wi-Fi 802.11n and Bluetooth.[47]
Processor
The Broadcom BCM2835 SoC used in the first generation Raspberry Pi[48] includes a RISC-based 700 MHz 32-bit ARM1176JZF-S processor, VideoCore IV graphics processing unit (GPU),[49] and RAM. It has a level 1 (L1) cache of 16 KB and a level 2 (L2) cache of 128 KB. The level 2 cache is used primarily by the GPU. The SoC is stacked underneath the RAM chip, so only its edge is visible. The ARM1176JZ(F)-S is the same CPU used in the original iPhone,[50] although at a higher clock rate, and mated with a much faster GPU.
The earlier V1.1 model of the Raspberry Pi 2 used a Broadcom BCM2836 SoC with a 900 MHz 32-bit, quad-core ARM Cortex-A7 processor, with 256 KB shared L2 cache.[51] The Raspberry Pi 2 V1.2 was upgraded to a Broadcom BCM2837 SoC with a 1.2 GHz 64-bit quad-core ARM Cortex-A53 processor,[14] the same one which is used on the Raspberry Pi 3, but underclocked (by default) to the same 900 MHz CPU clock speed as the V1.1. The BCM2836 SoC is no longer in production as of late 2016.
The Raspberry Pi 3 Model B uses a Broadcom BCM2837 SoC with a 1.2 GHz 64-bit quad-core ARM Cortex-A53 processor, with 512 KB shared L2 cache. The Model A+ and B+ are 1.4 GHz[52][53][54]
The Raspberry Pi 4 uses a Broadcom BCM2711 SoC with a 1.5 GHz (later models: 1.8 GHz) 64-bit quad-core ARM Cortex-A72 processor, with 1 MB shared L2 cache.[55][56] Unlike previous models, which all used a custom interrupt controller poorly suited for virtualisation, the interrupt controller on this SoC is compatible with the ARM Generic Interrupt Controller (GIC) architecture 2.0, providing hardware support for interrupt distribution when using ARM virtualisation capabilities.[57][58] The VideoCore IV of the previous models has also been replaced with a VideoCore VI running at 500 MHz.
The Raspberry Pi Zero and Zero W use the same Broadcom BCM2835 SoC as the first generation Raspberry Pi, although now running at 1 GHz CPU clock speed.[59]
The Raspberry Pi Zero 2 W uses the RP3A0-AU, which is a System-in-Package (SiP) design. The package contains a Broadcom BCM2710A1 processor, which is a 64-bit quad-core ARM Cortex-A53 clocked at 1 GHz, along with 512 MB of LPDDR2 SDRAM layered above.[60][61] The Raspberry Pi 3 also uses the BCM2710A1 in its Broadcom BCM2837 SoC, but clocked at a higher 1.2 GHz.
The Raspberry Pi Pico uses the RP2040,[62] a microcontroller containing dual ARM Cortex-M0+ cores running at 133 MHz, 6 banks of SRAM totaling 264 KB, and programmable IO for peripherals.[63]
The Raspberry Pi 5 uses the Broadcom BCM2712 SoC, which is a chip designed in collaboration with Raspberry Pi. The SoC features a quad-core ARM Cortex-A76 processor clocked at 2.4 GHz, alongside a VideoCore VII GPU clocked at 800 MHz. The BCM2712 SoC also features support for cryptographic extensions for the first time on a Raspberry Pi model. Alongside the new processor and graphics unit, the monolithic design of the earlier BCM2711 has been replaced with a CPU and chipset (southbridge) architecture, as the IO functionality has been moved to the Raspberry Pi 5's custom RP1 chip.[64]
Performance
While operating at 700 MHz by default, the first generation Raspberry Pi provided a real-world performance roughly equivalent to 0.041 GFLOPS.[65][66] On the CPU level the performance is similar to a 300 MHz Pentium II of 1997–99. The GPU provides 1 Gpixel/s or 1.5 Gtexel/s of graphics processing or 24 GFLOPS of general purpose computing performance. The graphical capabilities of the Raspberry Pi are roughly equivalent to the performance of the Xbox of 2001.
Raspberry Pi 2 V1.1 included a quad-core Cortex-A7 CPU running at 900 MHz and 1 GB RAM. It was described as 4–6 times more powerful than its predecessor. The GPU was identical to the original.[51] In parallelised benchmarks, the Raspberry Pi 2 V1.1 could be up to 14 times faster than a Raspberry Pi 1 Model B+.[67]
The Raspberry Pi 3, with a quad-core Cortex-A53 processor, is described as having ten times the performance of a Raspberry Pi 1.[68] Benchmarks showed the Raspberry Pi 3 to be approximately 80% faster than the Raspberry Pi 2 in parallelised tasks.[69]
The Raspberry Pi 4, with a quad-core Cortex-A72 processor, is described as having three times the performance of a Raspberry Pi 3.[17]
Overclocking
Most Raspberry Pi systems-on-chip can be overclocked to various degrees utilising the built in config.txt file in the boot sector of the Raspberry Pi OS. Overclocking is generally safe and does not automatically void the warranty of the Raspberry Pi; however, setting the "force_turbo" option to 1 bypasses voltage and temperature limits and voids the users warranty.[70] In Raspberry Pi OS the overclocking options on boot can also be made by a software command running "sudo raspi-config" on Raspberry Pi 1, 2, and original 3B without voiding the warranty.[71] In those cases the Pi automatically shuts the overclocking down if the chip temperature reaches 85 °C (185 °F); an appropriately sized heat sink is needed to protect the chip from thermal throttling.
Newer versions of the firmware contain the option to choose between five overclock ("turbo") presets that, when used, attempt to maximise the performance of the SoC without impairing the lifetime of the board. This is done by monitoring the core temperature of the chip and the CPU load, and dynamically adjusting clock speeds and the core voltage. When the demand is low on the CPU or it is running too hot, the performance is throttled, but if the CPU has much to do and the chip's temperature is acceptable, performance is temporarily increased with CPU clock speeds of up to 1.1 GHz, depending on the board version and on which of the turbo settings is used.
The overclocking modes are:
none | 700 MHz ARM | 250 MHz core | 400 MHz SDRAM | 0 overvolting |
---|---|---|---|---|
modest | 800 MHz ARM | 250 MHz core | 400 MHz SDRAM | 0 overvolting |
medium | 900 MHz ARM | 250 MHz core | 450 MHz SDRAM | 2 overvolting |
high | 950 MHz ARM | 250 MHz core | 450 MHz SDRAM | 6 overvolting |
turbo | 1000 MHz ARM | 500 MHz core | 600 MHz SDRAM | 6 overvolting |
Pi 2 | 1000 MHz ARM | 500 MHz core | 500 MHz SDRAM | 2 overvolting |
Pi 3 | 1100 MHz ARM | 550 MHz core | 500 MHz SDRAM | 6 overvolting. In system information, the CPU speed is indicated as 1200 MHz. When idling, speed lowers to 600 MHz.[71][72] |
In the highest (turbo) mode the SDRAM clock speed was originally 500 MHz, but this was later changed to 600 MHz because of occasional SD card corruption. Simultaneously, in high mode the core clock speed was lowered from 450 to 250 MHz, and in medium mode from 333 to 250 MHz.
The CPU of the first and second generation Raspberry Pi board did not require cooling with a heat sink or fan, even when overclocked, but the Raspberry Pi 3 may generate more heat when overclocked.[73]
RAM
The early designs of the Raspberry Pi Model A and B boards included only 256 MB of random access memory (RAM). Of this, the early beta Model B boards allocated 128 MB to the GPU by default, leaving only 128 MB for the CPU.[74] On the early 256 MB releases of models A and B, three different splits were possible. The default split was 192 MB for the CPU, which should be sufficient for standalone 1080p video decoding, or for simple 3D processing. 224 MB was for Linux processing only, with only a 1080p framebuffer, and was likely to fail for any video or 3D. 128 MB was for heavy 3D processing, possibly also with video decoding.[75] In comparison, the Nokia 701 uses 128 MB for the Broadcom VideoCore IV.[76]
The later Model B with 512 MB RAM, was released on 15 October 2012 and was initially released with new standard memory split files (arm256_start.elf, arm384_start.elf, arm496_start.elf) with 256 MB, 384 MB, and 496 MB CPU RAM, and with 256 MB, 128 MB, and 16 MB video RAM, respectively. But about one week later, the foundation released a new version of start.elf that could read a new entry in config.txt (gpu_mem=xx) and could dynamically assign an amount of RAM (from 16 to 256 MB in 8 MB steps) to the GPU, obsoleting the older method of splitting memory, and a single start.elf worked the same for 256 MB and 512 MB Raspberry Pis.[77]
The Raspberry Pi 2 has 1 GB of RAM.
The Raspberry Pi 3 has 1 GB of RAM in the B and B+ models, and 512 MB of RAM in the A+ model.[78][79][80] The Raspberry Pi Zero and Zero W have 512 MB of RAM.
The Raspberry Pi 4 is available with 1, 2, 4 or 8 GB of RAM.[81] A 1 GB model was originally available at launch in June 2019 but was discontinued in March 2020,[41] and the 8 GB model was introduced in May 2020.[82] The 1 GB model returned in October 2021.[83]
Networking
The Model A, A+ and Pi Zero have no Ethernet circuitry and are commonly connected to a network using an external user-supplied USB Ethernet or Wi-Fi adapter. On the Model B and B+ the Ethernet port is provided by a built-in USB Ethernet adapter using the SMSC LAN9514 chip.[84] The Raspberry Pi 3 and Pi Zero W (wireless) are equipped with 2.4 GHz WiFi 802.11n (150 Mbit/s) and Bluetooth 4.1 (24 Mbit/s) based on the Broadcom BCM43438 FullMAC chip with no official support for monitor mode (though it was implemented through unofficial firmware patching[85]) and the Pi 3 also has a 10/100 Mbit/s Ethernet port. The Raspberry Pi 3B+ features dual-band IEEE 802.11b/g/n/ac WiFi, Bluetooth 4.2, and Gigabit Ethernet (limited to approximately 300 Mbit/s by the USB 2.0 bus between it and the SoC). The Raspberry Pi 4 has full gigabit Ethernet (throughput is not limited as it is not funnelled via the USB chip.)
Special-purpose features
The RPi Zero, RPi1A, RPi3A+[86] and RPi4 can be used as a USB device or "USB gadget", plugged into another computer via a USB port on another machine. It can be configured in multiple ways, such as functioning as a serial or Ethernet device.[87] Although originally requiring software patches, this was added into the mainline Raspbian distribution in May 2016.[87]
Raspberry Pi models with a newer chipset can boot from USB mass storage, such as from a flash drive. Booting from USB mass storage is not available in the original Raspberry Pi models, the Raspberry Pi Zero, the Raspberry Pi Pico, the Raspberry Pi 2 A models, and the Raspberry Pi 2 B models with versions lower than 1.2.[88]
Peripherals
Although often pre-configured to operate as a headless computer, the Raspberry Pi may also optionally be operated with any generic USB computer keyboard and mouse.[89] It may also be used with USB storage, USB to MIDI converters, and virtually any other device/component with USB capabilities, depending on the installed device drivers in the underlying operating system (many of which are included by default).
Other peripherals can be attached through the various pins and connectors on the surface of the Raspberry Pi.[90]
Video
The video controller can generate standard modern TV resolutions, such as HD and Full HD, and higher or lower monitor resolutions as well as older NTSC or PAL standard CRT TV resolutions. As shipped (i.e., without custom overclocking) it can support the following resolutions: 640×350 EGA; 640×480 VGA; 800×600 SVGA; 1024×768 XGA; 1280×720 720p HDTV; 1280×768 WXGA variant; 1280×800 WXGA variant; 1280×1024 SXGA; 1366×768 WXGA variant; 1400×1050 SXGA+; 1600×1200 UXGA; 1680×1050 WXGA+; 1920×1080 1080p HDTV; 1920×1200 WUXGA.[91]
Higher resolutions, up to 2048×1152, may work[92][93] or even 3840×2160 at 15 Hz (too low a frame rate for convincing video).[94] Allowing the highest resolutions does not imply that the GPU can decode video formats at these resolutions; in fact, the Raspberry Pis are known to not work reliably for H.265 (at those high resolutions),[95] commonly used for very high resolutions (however, most common formats up to Full HD do work).
Although the Raspberry Pi 3 does not have H.265 decoding hardware, the CPU is more powerful than its predecessors, potentially fast enough to allow the decoding of H.265-encoded videos in software.[96] The GPU in the Raspberry Pi 3 runs at higher clock frequencies of 300 MHz or 400 MHz, compared to previous versions which ran at 250 MHz.[97]
The Raspberry Pis can also generate 576i and 480i composite video signals, as used on old-style (CRT) TV screens and less-expensive monitors through standard connectors – either RCA or 3.5 mm phono connector depending on model. The television signal standards supported are PAL-B/G/H/I/D, PAL-M, PAL-N, NTSC and NTSC-J.[98]
Real-time clock
When booting, the time defaults to being set over the network using the Network Time Protocol (NTP). The source of time information can be another computer on the local network that does have a real-time clock, or to a NTP server on the internet. If no network connection is available, the time may be set manually or configured to assume that no time passed during the shutdown. In the latter case, the time is monotonic (files saved later in time always have later timestamps) but may be considerably earlier than the actual time. For systems that require a built-in real-time clock, a number of small, low-cost add-on boards with real-time clocks are available.[99][100] The Raspberry Pi 5 is the first to include a real-time clock.[101] If an external battery is not plugged in, the Raspberry Pi 5 will use the Network Time Protocol, or will need to be set manually, as was the case in previous models.
The RP2040 microcontroller has a built-in real-time clock, but it can not be set without some form of user entry or network facility being added.
Pi Pico
Pi Compute Module
|
Pi Zero
Model A
|
Model B
|
J8 header and general purpose input-output (GPIO)
Raspberry Pi 1 Models A+ and B+, Pi 2 Model B, Pi 3 Models A+, B and B+, Pi 4, and Pi Zero, Zero W, Zero WH and Zero W 2 have the same 40-pin pinout (designated J8 across all models).[102] Raspberry Pi 1 Models A and B have only the first 26 pins.[103][104][105] The J8 header is commonly referred to as the GPIO connector as a whole, even though only a subset of the pins are GPIO pins. In the Pi Zero and Zero W, the 40 GPIO pins are unpopulated, having the through-holes exposed for soldering instead. The Zero WH (Wireless + Header) has the header pins preinstalled.
GPIO# | 2nd func. | Pin# | Pin# | 2nd func. | GPIO# | |
---|---|---|---|---|---|---|
+3.3 V | 1 | 2 | +5 V | |||
2 | SDA1 (I2C) | 3 | 4 | +5 V | ||
3 | SCL1 (I2C) | 5 | 6 | GND | ||
4 | GCLK | 7 | 8 | TXD0 (UART) | 14 | |
GND | 9 | 10 | RXD0 (UART) | 15 | ||
17 | GEN0 | 11 | 12 | GEN1 | 18 | |
27 | GEN2 | 13 | 14 | GND | ||
22 | GEN3 | 15 | 16 | GEN4 | 23 | |
+3.3 V | 17 | 18 | GEN5 | 24 | ||
10 | MOSI (SPI) | 19 | 20 | GND | ||
9 | MISO (SPI) | 21 | 22 | GEN6 | 25 | |
11 | SCLK (SPI) | 23 | 24 | CE0_N (SPI) | 8 | |
GND | 25 | 26 | CE1_N (SPI) | 7 | ||
0 | ID_SD (I2C) | 27 | 28 | ID_SC (I2C) | 1 | |
5 | N/A | 29 | 30 | GND | ||
6 | N/A | 31 | 32 | N/A | 12 | |
13 | N/A | 33 | 34 | GND | ||
19 | N/A | 35 | 36 | N/A | 16 | |
26 | N/A | 37 | 38 | Digital IN | 20 | |
GND | 39 | 40 | Digital OUT | 21 |
Model B rev. 2 also has a pad (called P5 on the board and P6 on the schematics) of 8 pins offering access to an additional 4 GPIO connections.[106] These GPIO pins were freed when the four board version identification links present in revision 1.0 were removed.[107]
GPIO# | 2nd func. | Pin# | Pin# | 2nd func. | GPIO# | |
---|---|---|---|---|---|---|
+5 V | 1 | 2 | +3.3 V | |||
28 | GPIO_GEN7 | 3 | 4 | GPIO_GEN8 | 29 | |
30 | GPIO_GEN9 | 5 | 6 | GPIO_GEN10 | 31 | |
GND | 7 | 8 | GND |
Models A and B provide GPIO access to the ACT status LED using GPIO 16. Models A+ and B+ provide GPIO access to the ACT status LED using GPIO 47, and the power status LED using GPIO 35.