Kevin Meehan Stephen Moskal Computer Architecture Winter 2012 Dr. Shaaban

Transcription

1 Kevin Meehan Stephen Moskal Computer Architecture Winter 2012 Dr. Shaaban

2 Contents Raspberry Pi Foundation Raspberry Pi overview & specs ARM11 overview ARM11 cache, pipeline, branch prediction ARM11 vs. ARM9 ARM11 future Programming the Raspberry Pi Raspberry Pi uses and project ideas Raspberry Pi vs. Arduino

3 Raspberry Pi Foundation UK registered educational charity Promote the study of computer science Cheap, low power, programmable computers Education, developing nations One Laptop per Child, Arduino

4 Raspberry Pi ultra low cost ($25 $35) credit card sized Linux computer 10/100 Ethernet, HDMI, SD card, USB GPIO to control external devices UART, I 2 C interface

5 SoC in Raspberry Pi: Broadcom BCM2835 SoC BCM2835 SoC (right) and Samsung K4P2G324ED Mobile DRAM (left)

6 System on Chip (SoC) What is System on Chip? A complex IC that integrates the major functional elements into a single chip or chipset. programmable processor on-chip memory accelerating function hardware (e.g. GPU) both hardware and software analog components Benefits of SoC Reduce overall system cost Increase performance Lower power consumption Reduce size

7 SoC in Raspberry Pi: Broadcom BCM2835 SoC Multimedia processor CPU ARM 1176JZF-S (armv6k) 700MHz RISC Architecture and low power draw Not compatible with traditional PC software GPU Broadcom Video IV Specialized graphical instruction sets RAM 512MB (Model B rev.2) 256 MB (Model A, Model B rev.1)

8 Connecting a Display and Audio HDMI Digital signal Video and audio signal DVI cannot carry audio signal Up to 1920x1200 resolution Composite RCA Analog signal 480i, 576i resolution 3.5mm jack

9 Universal Serial Bus Two USB 2.0 ports in RPi Buy a powered USB hub Passive models are cheaper and smaller, but lack the ability to run currenthungry devices like CD drives and external hard drives.

10 Form factor Storage: Secure Digital (SD) SD, Mini SD, Micro SD Types of Card SDSC (SD): 1MB to 2GB SDHC: 4GB to 32 GB SDXD up to 2TB The card should be at least 2GB in capacity to store all the required files

11 Ethernet (IEEE 802.3) Networking USB Ethernet Converter Wi-Fi Adapter

12 Networking - wireless IEEE Wi-Fi Protocols b, up to 11Mbps g, up to 54Mbps n, up to 300Mbps ac (draft), up to 1Gbps Frequency band 2.4GHz, 5GHz

13 Low Speed Peripherals General Purpose Input/Output (GPIO) Pins can be configured to be input/output Reading from various environmental sensors Ex: IR, video, temperature, 3-axis orientation, acceleration Writing output to dc motors, LEDs for status.

14

15 To use the pin numbers from the ribbon cable board: GPIO.setmode(GPIO.BCM) To use the pin numbers on raspberry pi board GPIO.setmode(GPIO.BOARD) All the pins have 3.3V logic levels and are not 5V-safe so the output levels are 0-3.3V and the inputs should not be higher than 3.3V. 45

16 Use Cobbler kit to extend the GPIO to breadboard 51

17 Specifications Broadcom BCM2835 System on a chip (SoC) [1] ARM1176JZF S processor 700 MHz with overclock capability to 1 GHz VideoCore IV GPU [2] Supports 1080p H.264 decoding and encoding 256 MB (model A) or 512 MB (model B) SDRAM [3] 26 available low level peripherals GPIO, UART, I2C, I2S, +3.3V, +5V, GND Price: $35

18 ARM11 Overview Based on the ARMv6 instruction set architecture. [4] 32 bit ARM ISA 16 bit Thumb ISA Used in embedded systems with low amounts of memory, not used in the RPi. 16 General purpose registers R0 R15, 15 general purpose mode specific registers, 7 status registers [5] Designed to run various operating systems (Unix/Linux, Android) on many different devices (iphone (Gen 3), Nintendo 3DS, etc.)

19

20 ARM11 Cache Organization Four way set associative cache of configurable size. [4] Virtually indexed and physically tagged Sizes in the range of 4 to 64KB Processor level one memory has separate instruction and data caches Data cache misses are non blocking [5] L1 cache s write buffer handles all RAW hazards L2 cache is off chip

21 Branch Prediction [6] Static Predictor First time run Forward conditional branches are assumed to be taken Backward conditionals are assumed to be not taken Dynamic Predictor Branch prediction cache as 128 entries based on the branch instruction address. States: Strongly not taken, weakly not taken, strongly taken, weakly taken. A return stack predicts unconditional subroutine return instructions.

22 ARM11 vs. ARM9 Cache is physically addressed in ARM11[7] ARM9 had cache aliasing and context switching issues. Redesigned pipeline 8 stages for ARM11 vs. 5 for ARM9 ARM11 has out of order completion No dynamic branch prediction in ARM9 (always assumed not taken) ARM11 has Load/Store and ALU paralellism ARM11 64 bit data paths vs. 32 bit ARM9

23 ARM11 Future Very little. The reason that the Raspberry Pi is extremely cheap is because the ARM11 is outdated. It s successor, the ARM Cortex A8 is a dual issue superscalar design, achieving double the IPC. [8] The A8 is seen in the iphone 4 The A8 is been also seceded by the Cortex A15 and can be seen in the Nvidia Tegra 4 [9]

24 Programming Raspberry Pi Raspbian, Arch Linux ARM, Debian, Android Chrome OS, RISC OS, Fedora Python, C, Perl, Java (must compile for ARMv6) Education Manual Scratch visual programming environment Raspberry Pi App store [10]

25 Raspberry Pi uses University of Southampton supercomputer [11] Programming introduction for children Senior Design projects

26 Raspberry Pi vs. Arduino Microprocessor Computer science multimedia Full Linux environment Python, C, Perl, Java Microcontroller Electronics Signal processing Real time applications C or C++

27 References [1] "BCM2835 Media Processor; Broadcom". 1 September Retrieved 13 February [2] Brose, Moses (30 January 2012). "Broadcom BCM2835 SoC has the most powerful mobile GPU in the world?". Grand MAX. Retrieved 13 February [3] "Model B now ships with 512MB of RAM". Retrieved 13 Febuary Retreived 13 February 2013 [4] Arm11 Processors Retrieved 13 Febuary 2013 [5] Davey, Oliveri (Spring 2009) The ARM11 Architecture Retrieved 12 February 2013 [6] Sloss, Symes, Wright ARM System Developer's Guide: Designing and Optimizing System Software page 661, Retreived 13 February 2013 [7] "The ARM11 Microarchitecture", ARM Ltd, 2002, Retreived 13 February 2013 [8] Cortex A8 Processors ARM Ltd Retreived 13 February [9] NVIDIA Announces "Project Denver" to Build Custom CPU Cores Based on ARM Architecture, Targeting Personal Computers to Supercomputers &xhtml=true&prid=705184, Retrieved 13 Feburary 2013 [10]] Brodkin, Jon. "ArsTechnica." Ars Technica. N.p., 17 Dec Web. 18 Feb < technology/2012/12/raspberry pi now has an app store and yes it hasgames/>. [11] "University of Southampton." Southampton Engineers a Raspberry Pi Supercomputer. Retreived 18 Feb <