Even though Raspberry Pi small similar in size to Arduino Uno, It is not a Microcontroller circuit. Raspberry Pi is unique that, with use of it one could do almost all the tasks any computer could do even the size is smaller.
when consider a computer hardware there are several components. the computer consist of a Micro processor, two chips Northridge and South-bridge and few supporting chips act as level convertors and interfaces such as USB, serial ports and parallel ports. when consider structure, Northridge is connected to Microprocessor and south-bridge connected to micro processor through north-bridge. South-bridge has relatively low speed than North-bridge. The graphic processor and RAM memory is connected to North-bridge and PCI, USB, Serial ports and BIOS are connected to South-bridge.
In Raspberry Pi all these components are included in a single chip. Therefore this chip is called System on Chip. Raspberry Pi inventor Mr. Eben Upton being an engineer of Broadcom and due to the agreement with the company, Raspberry Pi was included a Broadcom SOC. This chip custom made for Raspberry Pi including Micro processor, Graphic Processor and USB, GPIO,I2C and SPI interfaces.
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| Broadcom BCM2837 SOC Chip. |
Raspberry Pi concept Board 2006
This module was made by Eben Upton to test and experiment Raspberry Pi concept. this model was assembled on a veroboard on 2006. Has a Atmel ATmega644 microcontroller running with 22.1MHz clock. It also consist of 512K SRAM (Static-RAM) and it was used to store general program data and video data. If you look in the bellow picture, left most chip is the Atmel microcontroller and next to it is the SRAM chip. 19 pins out of 32 I/O pins in Atmel chip was used to send data to SRAM chip. A conventional Television was used as output video monitor for this device has resolution of 320 x 240. You could watch the first experiment from here. The video was done by Liz Upton, wife of Eben Upton.
Video data on SRAM was send to Television pixel by pixel through 74HC series 3 buffers to 3 ADC chips to generate video signal. time duration between vertical and horizontal blanking of video is used to process non video data.
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| Raspberry Pi Concept 2006 Edition |
After Establishing Raspberry Pi foundation, on May 2011 The Raspberry Pi prototype board was developed. this was small printed board type device. the unit had HDMI port to connect to screen and a USB drive on other end. Also the unit had on board camera. There were not much details on device on Internet. However people at Broadcom call the device 'MicroDB'.
Raspberry Pi Alpha Board
In August 2011, Raspberry Pi foundation had made a 'Raspberry Pi Alpha Board' It was not made to sell, rather to check and debug.
Raspberry Pi Beta Production Board
the foundation design 'Raspberry Pi Production Board'. And produced 100 printed circuit boards of this type. but only solder 10 boards. On January 1st 2012 they put soldered 10 devices on eBay on auction. intention of auction was to gather money to the foundation. the action was a success. the highest bid was GBP3500 and lowest was GBP930.
following is auction number 8. Picture was taken from blog of Paul Maunders. Follow the link to his blog post.
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| Raspberry Pi Beta Production Board.
https://www.pyrosoft.co.uk/blog/2012/01/13/raspberry-pi-8-first-photoshoot/ |
on 29th February 2012, new era began with realease of Raspberry Pi 1st production Board.this model is similer to Raspberry Pi Beta Production Board. But the RCA port used to connect to TV was yellow colour and the SD card slot was little bit shifted inward the board. 10,000 board was made and sold. The board was Assembled in China.
Raspberry Pi Full Production Board aka Raspberry Pi 1 Model B
Raspberry Pi 1 Model B is much similar to Raspberry Pi Beta Production Board and Raspberry Pi 1st Production Board. But there are slight differences. The board was released on April 2012. And was assembled in China. Distribution and sales was done through Farnel (Now Element14).
after September 2012 the board was began to manufacture in Sony Manufacturing Plant at Wales, UK. Liz Upton wrote about the decition in foundation web site.
"If you’ve been following us for a while, you’ll remember the time last year when we had to make the decision to manufacture the Raspberry Pi in China. The Raspberry Pi is a British enterprise, and as well as improving things in the computing industry’s future here by educating kids, we wanted to improve things in the present too, by actually doing our manufacture here in the UK."
Today every Raspberry Pi sold in United Kingdom is made in UK. and for the rest of the World, Raspberry Pi is manufacture in China. And Distribution is done through Element14.
Raspberry Pi 1 Model A
This model was released in February 2013. Much similar to Model B, but didn't include Ethernet port to connect to Network.
Raspberry Pi Computer Module
This model was released in April 2014. The SOC chip and RAM memory and eMMC Flash memory only include in this module. the size and shape similar to RAM card of Laptop computer. connecting interface too. Following picture show the module. The operating system and data is stored in eMMC flash memory instead of SD card in previous models.
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| Raspberry Pi Computer Module http://elinux.org/images/8/83/Compute-module.png |
Raspberry Pi 1 Model B+
On 14th July 2014, The Raspberry Pi foundation released new advanced model of Raspberry Pi 1 Model B. It was called Raspberry Pi Model B+. This model similar To Raspberry Pi 1 Model B in size and SOC chip. But new model contain 4 USB ports instead of 2. Therefore the unit could plug additional 2 USB devices addition to Key Board and Mouse. And instead of SD card the unit include MicroSD card. Also count of GPIO pins has increased from 26 to 40.
Raspberry Pi 2 Model B
On Februarry 2015 new advanced model was introduced. Raspberry Pi 2 Model B had new fast quad core SOC chip. Also the RAM memory was increased to 1GB. Rest of features were remain same as RPi 1 Model B+.
Raspberry Pi 3 Model B
After 4 years of release of first RPi, February 29, 2016 all new Raspberry Pi was released. The Raspberry Pi 3 Model B has more powerful 1.2GHz Quard Core 64bit SOC chip. This model has WiFi and Bluetooh conncetivity. But Ethernet port also remain. with this released RPi alllowed to run 64bit operating systems.
Raspberry Pi Zero and Raspberry Pi Zero W
In addition to Credit card size Raspberry Pi, the foundation released Raspberry Pi Zero. Smaller version of Raspberry Pi on November 2015. On 28th February 2017, 5th Birthday of Raspberry Pi foundation introduced Raspberry Pi Zero W. which is similar to Raspberry Pi Zero with on addition of Wi-Fi. Due to the demand one house in UK could order only one device.
Raspberry Pi Computer Module 3 and 3 Lite
These models were released on January 2017. Much similar to Raspberry Pi Computer Module. But have SOC chip and RAM memory same as RPi 3 Model B. But instead of MicroSD card in RPi 3 Model B, the unit has 4GB eMMC chip. but Lite version of this release do not have 4GB eMMC Flash.
we have talked about history of Raspberry Pi. We shall now consider important component SOC chip now.
SOC or System On Chip is made by including all the important components such as Micro processor, RAM memory, Graphic processor and etc. combining in to one chip. Devices such as Mobile Phones, Television and printers are also include SOC chips.
The SOC on Raspberry Pi include Micro Processor, Graphic Processor and Input/Output port. BCM2835, BCM2836 and BCM2837 are the part numbers of SOC included in Raspberry Pi so far. How ever these parts numbers are only available and included in Raspberry Pi only.
BCM2835
This chip included in RPi 1 Model A, RPi 1 Model B, RPi Computer Module 1, RPi Zero and RPi Zero W. The chip include single-core ARM1176JZF-S. It is a 32bit micro processor by ARM Holding of UK. It has ARM11 family with ARMv6 architecture. And Broadcom VideoCore IV graphic processor. Clock speed the SOC chip runs varies from model to model. RPi 1 Model A, RPi 1 Model B, RPi Computer Module 1 runs on 700MHz speed while RPi Zero and RPi Zero W runs on 1GHz speed.
Famous Apple iPhones are also include SOCs with ARM micro processors.
BMC2836
This SOC include only in RPi 2 Model B. It run by 700MHz clock speed. include 32bit Quard-core ARM Cortex-A7 Micro Processor.
BMC2837
The RPi 2 Model B, RPi 3 Model B and RPi Computer Module 3, 3 Lite modules made after October, 2016 include this SOCs. This include Quard-core ARM Cortex-A53 Micro processor. ARM Cortex-A53 has architecture of ARMv8-A. The clock rate on RPi 2 Model B is 900MHz and RPi 3 Model B and RPi Computer Module has 1.2GHz speed.
In addition to SOC Raspberry Pi include many other components. For example the switch mode power supply to reduce voltage from 5V to 3.3V and Ethernet controller chip.
This conclude blog post regarding Raspberry Pi hardware. Next post is expected to be regarding the operating systems used in Raspberry Pi.
References :
1. https://en.wikipedia.org/wiki/System_on_a_chip
2. https://en.wikipedia.org/wiki/Northbridge_(computing)
3. http://elinux.org/RPi_HardwareHistory
4. https://www.raspberrypi.org/blog/raspberry-pi-2006-edition/
5. https://www.pyrosoft.co.uk/blog/2012/01/13/raspberry-pi-8-first-photoshoot/
මෙම ලිපියෙහි සිංහල පරිවර්තනය සඳහා පිවිසෙන ඉලෙක්ට්රොනික ලෝකය
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