Olimex A20-OLINUXINO-LIME2, A20-OLINUXINO-LIME2-4GB USER’S MANUAL

A20-OLINUXINO-LIME2

and

A20-OLINUXINO-LIME2-4GB

Open-source single-board Android/Linux mini-computer

USER’S MANUAL

Revision B, March 2015

Designed by OLIMEX Ltd, 2014

All boards produced by Olimex LTD are ROHS compliant

DISCLAIMER

The information in this document is provided in connection with Olimex products. No license, express or implied or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Olimex products.

This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://www.creativecommons.org/licenses/by-sa/3.0/.

This hardware design by Olimex LTD is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

The software is released under GPL.

It is possible that the pictures in this manual differ from the latest revision of the board.

The product described in this document is subject to continuous development and improvements. All particulars of the product and its use contained in this document are given by OLIMEX in good faith. However all warranties implied or expressed including but not limited to implied warranties of merchantability or fitness for purpose are excluded. This document is intended only to assist the reader in the use of the product. OLIMEX Ltd. shall not be liable for any loss or damage arising from the use of any information in this document or any error or omission in such information or any incorrect use of the product.

This evaluation board/kit is intended for use for engineering development, demonstration, or evaluation purposes only and is not considered by OLIMEX to be a finished end-product fit for general consumer use. Persons handling the product must have electronics training and observe good engineering practice standards. As such, the goods being provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards.

Olimex currently deals with a variety of customers for products, and therefore our arrangement with the user is not exclusive. Olimex assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or services described herein.

THERE IS NO WARRANTY FOR THE DESIGN MATERIALS AND THE COMPONENTS USED TO CREATE A20-OLINUXINO-LIME2 AND A20-OLINUXINO-LIME2-4GB. THEY ARE CONSIDERED SUITABLE ONLY FOR, RESPECTIVELY, A20-OLINUXINO-LIME2 OR A20-OLINUXINO-LIME2-4GB.

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Table of Contents

DISCLAIMER ............................................................................................................. 2

CHAPTER 1: OVERVIEW ........................................................................................ 5

1. Introduction to the chapter ....................................................................................................... 5

1.1 Features ..................................................................................................................................... 5

1.2 Target market and purpose of the board ............................................................................... 6

1.3 Board variants .......................................................................................................................... 6

1.4 Board version used in the manual .......................................................................................... 6

1.5 Document organization ........................................................................................................... 7

CHAPTER 2: SETTING UP THE OLINUXINO BOARD ..................................... 8

2. Introduction to the chapter ....................................................................................................... 8

2.1 Electrostatic and electrical polarity warning ........................................................................ 8

2.2 Requirements ........................................................................................................................... 8

2.3 Powering the board ................................................................................................................ 10

2.4 Button functions ..................................................................................................................... 11

2.5 Interacting with the board .................................................................................................... 11

2.5.1 Serial connection at UART0 ........................................................................................................................ 11

2.5.2 HDMI monitor .............................................................................................................................................. 12

2.5.3 LCD display .................................................................................................................................................. 12

2.5.4 SSH via mini USB cable in Debian ............................................................................................................. 12

2.5.5 SSH via Ethernet connector ........................................................................................................................ 13

2.6 Changing the default video output resolution ..................................................................... 13

2.7 Connecting and calibrating a display ................................................................................... 16

2.7.1 Android calibration ...................................................................................................................................... 16

2.7.2 Debian calibration ........................................................................................................................................ 17

2.8 GPIO under Debian ............................................................................................................... 17

2.9 I2C and SPI under Debian .................................................................................................... 18

2.10 Software support .................................................................................................................. 18

CHAPTER 3: A20-OLINUXINO-LIME2 BOARD DESCRIPTION ................... 20

3. Introduction to the chapter ..................................................................................................... 20

3.1 Layout (top view) ................................................................................................................... 20

3.2 Layout (bottom view) ............................................................................................................. 21

CHAPTER 4: THE ALLWINNER A20 MICROCONTROLLER ....................... 22

4. Introduction to the chapter ..................................................................................................... 22

4.1 The processor ......................................................................................................................... 22

4.2 Block diagram ........................................................................................................................ 23

CHAPTER 5: CONTROL CIRCUITY ................................................................... 24

5. Introduction to the chapter ..................................................................................................... 24

5.1 Reset ........................................................................................................................................ 24

5.2 Clocks ...................................................................................................................................... 24

5.3 Power supply circuit .............................................................................................................. 24

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CHAPTER 6: CONNECTORS AND PINOUT ...................................................... 25

6. Introduction to the chapter ..................................................................................................... 25

6.1 UART0 interface .................................................................................................................... 25

6.2 MicroSD card connector ....................................................................................................... 25

6.2.1 SD/MMC1 slot .............................................................................................................................................. 26

6.3 PWR jack ................................................................................................................................ 27

6.4 USB_OTG ............................................................................................................................... 27

6.5 USB_HOST connectors ......................................................................................................... 29

6.6 Gigabit Ethernet .................................................................................................................... 30

6.7 HDMI connector .................................................................................................................... 31

6.8 SATA connector and power ................................................................................................... 32

6.9 GPIO connectors .................................................................................................................... 33

6.9.1 GPIO-1 (General Purpose Input/Output) 40pin connector ..................................................................... 33

6.9.2 GPIO-2 (General Purpose Input/Output) 40pin connector ..................................................................... 35

6.9.3 GPIO-3 (General Purpose Input/Output) 40pin connector ..................................................................... 36

6.9.4 GPIO-4 (General Purpose Input/Output) 20pin connector ..................................................................... 36

6.10 LCD_CON 40pin connector ................................................................................................ 37

6.11 Jumper description .............................................................................................................. 39

6.12 Additional hardware components ...................................................................................... 40

CHAPTER 7: SCHEMATICS .................................................................................. 41

7. Introduction to the chapter ..................................................................................................... 41

7.1 Eagle schematic ...................................................................................................................... 41

7.2 Physical dimensions ............................................................................................................... 42

CHAPTER 8: REVISION HISTORY AND SUPPORT ........................................ 43

8. Introduction to the chapter ..................................................................................................... 43

8.1 Document revision ................................................................................................................. 43

8.2 Board revision ........................................................................................................................ 43

8.3 Useful web links and purchase codes ................................................................................... 44

8.4 Frequently asked questions ................................................................................................... 45

8.5 Product support ..................................................................................................................... 48

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CHAPTER 1: OVERVIEW

1. Introduction to the chapter

Thank you for choosing this OLinuXino single board computer from Olimex! This document provides a user’s guide for the Olimex A20-OLinuXino-LIME2 board. As an overview, this chapter gives the scope of this document and lists the board’s features. The document’s organization is then detailed.

The A20-OLinuXino-LIME2 development board enables code development of applications running on the A20 microcontroller, manufactured by Allwinner Technology from China.

OLinuXino is an open-source, open-hardware project and all design files are available to the customer.

1.1 Features

The board has the following set of features:

• A20 Cortex-A7 dual-core ARM Cortex-A7 CPU and dual-core Mali 400 GPU

• 1GB DDR3 RAM memory

• 1000MBit native Ethernet

• 4GB NAND FLASH memory (available only on the 4GB version of the board)

• Android already loaded on the NAND (available only on the 4GB version of the board)

• SATA connector with 5V SATA power jack

• Native HDMI

• Capable of FullHD (1080p) video playback

• 2x USB Low-Full-High-Speed hosts with power control and current limiter

• USB-OTG with power control and current limiter

• LiPo Battery connector with battery-charging capabilities

• LCD row of pins (0.05'' step)

• 160 GPIOs on four GPIO rows of pins (0.05'' step)

• MicroSD card connector

• DEBUG-UART connector for console debug with USB-SERIAL-CABLE-F

• Status LED

• Battery charge status LED

• Power LED

• 2KB EEPROM for MAC address storage and more

• 2 BUTTONS with ANDROID functionality + RESET button

• 2 mount holes

• 5V input power supply, noise immune design

• PCB dimensions: 84×60 mm

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1.2 Target market and purpose of the board

The boards from the OLinuXino family are easy to setup and powerful. It is possible to use them in almost any application as a host board. They are suitable for embedded programming enthusiasts, Linux and Android gadget fans (they can just use the board as a media center or fully functional Linux-PC, for instance) and also professionals (since its low cost makes it very good solution for application-orientated embedded systems). The main usage of the board is software embedded development without the urge of understanding perfectly the hardware.

The LIME boards are a special kind of OLinuXino boards – they are as small as possible while maintaining a remarkable stand-alone functionality. The strong points of these boards are the processor speed, the small form factor and the low price-to-productivity ratio.

Customers have full access to the technical documentation of the board. The software is released under General Purpose License and the board is considered open-hardware – all schematics and board design files are available to the customer under the Creative Commons AttributionShareAlike 3.0 Unported License.

1.3 Board variants

There are two major board variants named: A20-OLinuXino-LIME2 and A20-OLinuXino-LIME24GB. The 4GB version has a built-in NAND memory that allows the storage of an operating system without the need of a SD card. The 4GB version comes with already programmed Android image.

A20-OLinuXino-LIME2 looks similar to both A20-OLinuXino-LIME and to A10-OLinuXinoLIME. The major differences between A20-OLinuXino-LIME2 and A20-OLinuXino-LIME are:

1. LIME2 has gigabit Ethernet (GbE), compared to the standard 100Mb Ethernet of the LIME.

2. LIME2 design provides double the RAM memory, compared to the LIME design (1024 vs 512).

3. Much better routing of DDR3 memory.

4. Increased the number of layers from 6 in LIME to 8 in LIME2.

5. Corrected pinout of the LCD connector.

6. The price tag

Due to the hardware differences listed above the Linux and Android distributions of the LIME2 and LIME boards are not identical. Furthermore, some of the hardware extensions are not compatible with both of the designs. For example, the A10-OLINUXINO-LIME-UEXT is not compatible with A20-OLinuXino-LIME2 board.

1.4 Board version used in the manual

Revision B boards and resources were used while writing this document. It is possible that they are outdated so it is always recommended to download the latest sources from the GitHub page of the board (https://github.com/OLIMEX/OLINUXINO/tree/master/HARDWARE).

Some peripherals, documents or software may be suitable for both the A20-LIME2 and the A20LIME designs but it is generally advised to use resources for the specific board.

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1.5 Document organization

Each section in this document covers a separate topic, organized as follows:

– Chapter 1 is an overview of the board usage and features – Chapter 2 provides a guide for quickly setting up the board and software notes – Chapter 3 contains the general board diagram and layout – Chapter 4 describes the component that is the heart of the board: the A20 – Allwinner

processor

– Chapter 5 is an explanation of the control circuitry associated with the microcontroller – Chapter 6 covers the connector pinout, peripherals and jumper description – Chapter 7 provides the schematics and the dimensions of the board

– Chapter 8 contains the revision history, useful links and support information

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CHAPTER 2: SETTING UP THE OLINUXINO BOARD

2. Introduction to the chapter

This section helps you set up the development board for the first time. Please consider first the electrostatic warning to avoid damaging the board, then discover the hardware and software required to operate the board.

The procedure to power up the board is given, and a description of the default board behavior is detailed.

2.1 Electrostatic and electrical polarity warning

A20-OLinuXino-LIME2 is shipped in a protective anti-static package. The board must not be exposed to high electrostatic potentials. A grounding strap or similar protective device should be worn when handling the board. Avoid touching the component pins or any other metallic element.

Ensure that your development board gets attached to properly working hardware. For example, it is common for cheap HDMI monitors to lack grounding. Avoid TVs which have no grounding on their power supply cable! If you can’t avoid them try to add the grounding yourself, if this is not possible please use USB-ISO to save your development board from potential over voltage.

If you connect other electrical devices to the LIME2 board make sure that they have equal electrical polarity. For example, when you connect an HDMI cable between a TV and the board it is a good idea to have them both connected to the same electrical source (to the same utility power socket). This might be said for a serial cable connected between a PC and the board's DEBUG port. In rare cases different polarity might cause hardware damage to the board.

2.2 Requirements

In order to set up the A20-OLinuXino-LIME2 optimally one or more additional items may be used. They might be generally placed in three categories:

Required – items that are needed in order to achieve minimum functionality; Recommended – items that is good to have in order to be able to interact with the most important

of the features of the board;

Additional – items that provide access to additional features or expand the features of the board.

Required items:

- USB type A to USB mini cable – to connect to a personal computer; used for powering the board and uploading new Android image to the NAND memory (if your board has 4GB NAND); can also be used to access the Linux of the board

- Input device – either a mouse/keyboard or touchscreen LCD

- Output device – either HDMI cable + native HDMI monitor/screen/projector; or USB-SERIALCABLE-F + personal computer (for Linux and/or Android debugging)

- SD card with compatible image – if you have the board version with NO additional NAND memory you will need it to use one of the images available.

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2.3 Powering the board

There are three possible ways of powering A20-OLinuXino-LIME2 – via external supply providing 5V DC at the power jack, from 5V USB port via USB_OTG connector or from 3.7V Li-Po battery via the LIPO_BAT. Note that the board might consume up to 650mA of current at 5V when there are no peripherals connected to the USB hosts. Make sure your power supply is able to provide at least 1A before. Depending on your preferred way of powering you might need additional hardware.

Important: Not all USB ports would be able to provide enough power for the board. Try using another USB port/USB hub or a cable of higher quality.

If you have an LCD display connected to the board or external 2.5'' hard disk then the USB will NOT be sufficient source of power.

The best practice is to never count on the mini USB-OTG as a single source of power for the board!

The preferred way of powering the board is via the PWR jack with 5V DC. This would make the board fully powered and able to power all the peripherals connected to it.

Note that when powering the board from the USB_OTG, the current provided might be insufficient to also power a bigger LCD connected to the LCD_con. However, this power option is capable of driving the board when using external display connected to the HDMI connector.

The typical consumption of A20-OLinuXino-LIME2 is between 400mA and 650mA depending on the current load.

If the board has entered power-down state you can bring it back without restart using the PWR_BUT. The PWR_BUT is also used to start the board when powered from a Li-Po battery on the battery connector.

Sometimes when starting Android it is possible the board to enter battery save mode even before booting fully. Especially, if you have turned off the board without quick boot mode enabled. In this case you should press the PWR button for at least 5 seconds which would allow the board to start.

For the European customers we sell two power supply adapters, please check chapter 2.2. We also sell USB OTG to USB type A cables if you lack such.

The default username/password combination for the default Linux image on the SD card (if purchased) is: root/olimex.

Note that it is normal that when the board is powered some integrated circuits might appear hotter than others. This is perfectly normal for some chips – for instance – voltage regulators and the main processor.

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2.4 Button functions

The bellow three buttons usually are supported under both Android and Debian:

PWR – used to perform software turn off, software turn on; used to turn on board when powered by battery – has to be held down for at least 5 seconds to perform each action

RESET – used for hardware reset of the board RECOVERY – used to wake up the board from sleep

It is recommended to always make a soft “turn off” of the board. If that is not possible then please hold PWR button down for a few seconds to “turn off the board”. Then you are free to remove the power supply. If you disconnect the power supply (either the USB, the battery or the power jack) before turning off the board you may corrupt your SD card. If you have placed NAND memory you can corrupt the image on the NAND memory.

2.5 Interacting with the board

There are five typical ways to interact with A20-OLinuXino-LIME2. You can interact with A20OLinuXino-LIME2 and:

- a personal computer or another board via UART0 and a serial debug cable

- an HDMI monitor via the HDMI connector and an HDMI cable

- an LCD display via LCD_CON connector and 0.05'' step 40-pin cable

- a personal computer or another board via the mini USB connector and a mini USB cable, using SSH protocol

- a personal computer via the Ethernet connector and a LAN cable, using SSH protocol

More details on each of the connections might be found in the consequent sub-chapters.

Note that not all interface options are available for all images. Furthermore, some of the ways of interaction are (obviously) not suitable for Android OS. The official Debian image should give you the most possible options of interfacing the board!

Using HDMI, LCD_CON or LAN might require additional configurations. Furthermore, it is possible to corrupt the output settings over those interfaces and, thus, lose the output. In such cases, you can always use the serial cable USB-SERIAL-CABLE-F as a reliable way to establish connection to the board.

2.5.1 Serial connection at UART0

The default and recommended way to communicate with the Linux operating system of the board is using the serial connection available at UART0 connector. You would probably need an USB<>SERIAL cable for such a connection. Even if you intend to use HDMI or LCD it is a good idea to have it as a basis – the video output is not always reliable and if you set wrong display settings you would be unable to recover the software without an alternative connection.

We distribute a ready-to-use cable. Even if you already have such a cable or you decide to purchase it elsewhere it is advisable to check this product page for a reference: Product page

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Note that the levels at board's UART0 are in CMOS level (3.3V) and you would need a MAX232 convertor to bring them to TTL one! That is true for the RX and TX also! You would need to consider that if you decide to make your own cable.

The cable probably needs drivers – after successful driver installation a COM port device would show up in the hardware manager of your computer. Then you would need to connect the serial cable wires to the board as follows: RX line to UART1-TX pin; TX line to UART1-RX pin; GND to GND. The last pin of UART1 connector is named 3.3V and it can be used to power the board, if you have other ways of power the board leave 3.3V pin unconnected! Be careful to avoid the connection to the serial cable else there would be a short-circuit. Make sure that the serial cable is connected to your personal computer and recognized properly after driver installation.

Then open a terminal program on the serial (COM) port which the cable is associated with. The settings for the connection are 115200 baud, 8-N-1. After everything else is set, you would need to power the board as explained in “2.3 Powering the board”.

2.5.2 HDMI monitor

The board comes equipped with HDMI connector to connect to a compatible monitor. However, there is no cable included. Make sure to use a tested HMDI cable.

All official Debian and Android images for A20-OLinuXino-LIME2 have HDMI output enabled by default. The board should work out-of-the-box with a native HDMI monitor.

The default HDMI resolution in the official images is 720p60 (1280×720p at 60Hz). In order to change that setting the video output on the LCD display you would need to run a configuration script (if you use Debian Linux) or download a suitable image (if you use Android). Video output settings are hard-coded in Android images but there are ways to edit the images. You might more information about editing pre-built Android images at this wiki article: how to edit prebuilt Android

images.

More information about the video output settings and the usage of video settings script might be found in chapter “2.6 Changing the default image resolution”.

2.5.3 LCD display

Various LCD displays can be attached to A20-OLinuXino-LIME2 and used to interact with the board.

Depending on the display chosen and whether you attempt to run Debian Linux or Android additional video settings configuration may be required. It is always a good idea to have one of the other connection options available as back-up (in case the video output settings need modification).

For more information refer to chapter “2.7 Connecting and calibrating a display”.

2.5.4 SSH via mini USB cable in Debian

The latest official Debian Linux image allows the use the USB_OTG connector for SSH connection without the need of a LAN cable or a serial cable. You can use a mini USB cable connected between your host PC and the on-board mini USB connector. For connection convenience there is a

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DHCP server running specifically for USB0 interface. The DHCP server should give IP address to the new USB0 interface of your host PC so you can make SSH connection from your PC to the default board IP address of the USB0 interface – 192.168.2.1.

You can connect to the board using a mini USB cable and an SSH client (if you use Windows you might use "puTTY", for example) at address 192.168.2.1.

For Windows operating system – upon connection, the board should show up in "Windows Device Manager" as "RNDIS Ethernet Gadget". You might be asked to install a driver. The drivers can be found online as "RNDIS driver" (Remote Network Driver Interface Specification). The drivers are provided by Microsoft and they should be available for every Windows distribution – refer to the respective files and articles provided by Microsoft on how to install the required drivers.

2.5.5 SSH via Ethernet connector

SSH protocol allows you to login remotely to the command-line interface of the A20-OLinuXinoLIME board. You would need an active Ethernet connection to the board.

The newest images have a configuration that allows SSH via the Ethernet connector. The static IP address to access the board is 192.168.1.254

2.6 Changing the default video output resolution

Depending on the display or the screen you want to use with the A20-OLinuXino-LIME2, you might need to apply software changes to the prebuilt Android or Linux image. The typical OLinuXino user would not need to edit the files, however.

To ease the process of changing the resolution we have compiled a number of Android images for the Android users (with hard-coded video output settings). Alternatively, for Debian Linux users, we have provided a shell script that can be executed in order to set preferred video output and resolution.

For Android that you boot from the NAND memory you would need an image suitable for the specific resolution. Download locations to such images might be found at the wiki article for the A20 board here: https://www.olimex.com/wiki/A20-OLinuXino-LIME2.

For Linux Debian you would need to execute a shell script to be able to change the resolution. It is very good idea to use a serial cable for connection to the board from a personal computer since in this case you are dependent on a video resolution (a cable like USB-SERIAL-CABLE-F). When the board boots type:

./change_display*

or

./change_display_a20_olimex.sh

It looks like this:

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Then the main menu of the video configuration script shows up and you can select the desired interface (LCD, HDMI or VGA):

The supported resolutions for LCD:

1. 4.3" (480×272)

2. 7" (800×480)

3. 10" (1024×600)

The supported resolutions for HDMI:

0. 480i

1. 576i

2. 480p

3. 576p

4. 720p50

5. 720p60

6. 1080i50

7. 1080i60

8. 1080p24

9. 1080p50

10. 1080p60

The supported resolutions for VGA (please note that there is no VGA connector and you would need to install additional hardware - more instructions on the VGA signals might be found in the chapter 6):

0. 1680×1050

1. 1440×900

2. 1360×768

3. 1280×1024

4. 1024×768

5. 800×600

6. 640×480

7. 1920×1080

8. 1280×720

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Chose the resolution that suits you and reboot the board.

If you decide to edit the configurations yourself the easiest way would be to do it on the board. This can be done offline too (manipulating the image located on the microSD card via a microSD card reader).

The tools for script.bin changing are located in /opt/sunxi-tools directory:

#cd /opt/sunxi-tools #./chscr.sh

This will convert script.bin file from sdcard to script.fex file and the file will be opened using nano editor. Now you can change the board modules and parameters, save the changes ("CTRL"+"X"; confirm with "Y") and exit ("CTRL"+"X" again) from nano editor.

#./wrscr.sh

this will convert script.fex to script.bin and the script.bin file will be written to the microSD card.

reboot

Reboot the board and the new settings would be applied.

Alternatively, you can do the changes on the microSD card off the board. You would need to remove the microSD card and explore it in a microSD card reader. You would need to edit the configuration file script.bin and edit the settings inside. This file is usually located in Script.bin can't be opened in the binary format so you would need to convert it to .fex file format first. There are ready-to-use tools that convert script.bin <-> script.fex. Note that script.bin/fex contains configuration settings and definitions not only for the video output but also for the pin descriptions and names; power setting and much more. If you really want to modify and customize the default images (to change port functions, port names, to disable specific peripherals) you would need to be able to edit the script files. Please refer to the following web page for more information:

http://linux-sunxi.org/Fex_Guide

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