OLIMEX A20-OLinuXino-MICRO User Manual

A20-OLinuXino-MICRO

Open-source single-board

Android/Linux mini-computer

USER’S MANUAL

Revision I, May 2014

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-MICRO. THEY ARE CONSIDERED SUITABLE ONLY FOR A20-OLINUXINO-MICRO.

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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 Organization ............................................................................................................................. 6

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 .................................................................................................................. 9

2.4 Prebuilt software .................................................................................................................... 10

2.5 Changing the default image resolution ................................................................................ 10

2.6 Calibrating a display ............................................................................................................. 12

2.6.1 Android calibration ...................................................................................................................................... 12

2.6.2 Debian calibration ........................................................................................................................................ 12

2.7 Software support .................................................................................................................... 12

2.8 Button functions and NAND image restore in Android ..................................................... 12

CHAPTER 3: A20-OLinuXino-MICRO BOARD DESCRIPTION ..................... 14

3. Introduction to the chapter ..................................................................................................... 14

3.1 Layout (top view) ................................................................................................................... 14

3.2 Layout (bottom view) ............................................................................................................. 15

CHAPTER 4: THE ALLWINNER A20 EMBEDDED PROCESSOR ................. 16

4. Introduction to the chapter ..................................................................................................... 16

4.1 The processor ......................................................................................................................... 16

4.2 Block diagram ........................................................................................................................ 17

CHAPTER 5: CONTROL CIRCUITY ................................................................... 18

5. Introduction to the chapter ..................................................................................................... 18

5.1 Reset ........................................................................................................................................ 18

5.2 Clocks ...................................................................................................................................... 18

5.3 Power supply circuit .............................................................................................................. 18

CHAPTER 6: CONNECTORS AND PINOUT ...................................................... 19

6. Introduction to the chapter ..................................................................................................... 19

6.1 Communication with the A20 ............................................................................................... 19

6.1.1 USB-OTG communication (NAND firmware repair/update) .................................................................. 19

6.1.2 UART0, UEXT1, UEXT2 interface ............................................................................................................ 21

6.2 SD card connectors ................................................................................................................ 22

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6.2.1 SD/MMC1 slot .............................................................................................................................................. 22

6.2.2 SD/MMC slot ................................................................................................................................................ 23

6.3 PWR jack ................................................................................................................................ 24

6.4 MIC_IN & HEADPHONES connectors .............................................................................. 25

6.5 USB_OTG connector ............................................................................................................. 26

6.6 USB_HOST connector ........................................................................................................... 27

6.7 Ethernet .................................................................................................................................. 28

6.8 HDMI connector .................................................................................................................... 30

6.9 VGA connector ....................................................................................................................... 31

6.10 SATA connector and power ................................................................................................. 32

6.11 GPIO-1 (General Purpose Input/Output) 14pin connector** ......................................... 32

6.12 GPIO-2 (General Purpose Input/Output) 40pin connector ............................................. 33

6.13 GPIO-3 (General Purpose Input/Output) 10pin connector ............................................. 34

6.14 LCD_CON 40pin connector ................................................................................................ 34

6.15 Jumper description .............................................................................................................. 36

6.16 Additional hardware components ...................................................................................... 36

CHAPTER 7: SCHEMATICS .................................................................................. 37

7. Introduction to the chapter ..................................................................................................... 37

7.1 Eagle schematic ...................................................................................................................... 37

7.2 Physical dimensions ............................................................................................................... 38

CHAPTER 8: REVISION HISTORY AND SUPPORT ........................................ 39

8. Introduction to the chapter ..................................................................................................... 39

8.1 Document revision ................................................................................................................. 39

8.2 Board revision ........................................................................................................................ 40

8.3 Useful web links and purchase codes ................................................................................... 41

8.4 Frequently asked questions ................................................................................................... 42

8.5 Product support ..................................................................................................................... 44

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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 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-MICRO 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 documentation is available to the customer.

1.1 Features

The board has the following set of features (please note the difference between the two versions of the board):

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

• 1GB DDR3 RAM memory

• 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

• Built-in FullHD support (1080p)

• 2 x USB High-speed host with power control and current limiter

• USB-OTG with power control and current limiter

• HDMI output with ESD protectors

• VGA output on 6-pin 1.25mm (0.05'') step connector

• 100MBit native Ethernet

• Battery connector with battery-charging capabilities

• Audio headphones output on connector

• Microphone input on connector

• 2 x UEXT connectors

• LCD connector compatible with with 4.3'', 7.0'', 10.1" LCD modules from Olimex

• 160 GPIOs on three GPIO connectors

• MicroSD card connector

• SD/MMC card connector

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

• GPIO LED

• Battery charge status LED

• 2KB EEPROM for MAC address storage and more

• 10 BUTTONS with ANDROID functionality + RESET button

• 4 mount holes

• 6-16V input power supply, noise immune design

• PCB dimensions: (5600×3250) mils ~ (142.24×82.55) 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 strong points of the boards are the processor speed, the small form factor and the low price-toproductivity 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-MICRO and A20-OLinuXinoMICRO-4GB. The 4GB version has a built-in NAND memory suitable for the storage of an operating system without the need of a SD card. The 4GB version comes with already programmed Android 4.2.2 image.

The other Olimex boards with close characteristics are the ones with A13 and A10/A10s microcontrollers. The A13 boards feature a generation older processor but since they have been longer on the market they have better Linux and Android support. The A10/A10s boards feature single (than A20) processor core but they are more energy efficient making them better choices for handheld devices and devices requiring power efficiency.

Additional Android and Linux support and features are added overtime. The Linux support is a work in progress and you should not expect full Linux support after the initial volume of such boards have become available on the market. If you are in a hurry consider the older OLinuXino designs (which have almost everything supported, have examples available and so on).

1.4 Board version used in the manual

Boards from revisions E and F 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.

1.5 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

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– 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 OLinuXino 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

OLinuXino 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.

If you connect other electrical devices to the A20 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-MICRO 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)

- 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); or OLIMEX LCD (TS) display + 40-pin CABLE-IDC40-15cm; or A20-VGA-CABLE + VGA monitor/screen/projector

- 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.

Recommended items:

- External USB hub – to split the USB_HOST mounted on the board; you need that to connect more USB devices

- External power supply unit – 6-16V DC, 5W required (10V @ 0.5A) – for optimal power

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- USB-SERIAL-CABLE-F – for Android/Linux debugging on UART0

- CABLE-IDC40-15cm – cable used for LCD_CON ↔ Olimex LCD display

- Adapter cable for the 6-pin VGA connector to standard VGA 15-pin connector

Additional items include:

- Audio device for HEADPHONES jack

- Ethernet cable for wired Ethernet

- A number of extension modules that can add functionality or interface to the board on the UEXT connector; these can be explored here: https://www.olimex.com/Products/Modules/

Some of the above-suggested items can be purchased by Olimex, for instance:

SY0612E – reliable power supply adapter 50Hz (for EU) 12V/0.5A for A20-OLinuXino-MICRO SY0612E-CHINA – cheaper power supply adapter 50Hz (for EU) 12V/0.5A for A20-OLinuXino-

MICRO A20-Android-SD – a tested class 10 micro SD card with the latest (by the time of leaving the Olimex facilities) official Android release A20-Debian-SD – a tested class 10 micro SD card with the latest (by the time of leaving Olimex facilities) official Debian Linux release

USB-SERIAL-CABLE-F – USB serial console cable female USB-MINI-CABLE – standard USB type A to USB type mini cable A20-VGA-CABLE – adapter from 6-pin connector to 15-pin one CABLE-IDC40-15cm – cable for LCD to LCD_CON connection A13-LCD43TS – low-cost 4.3'' LCD display with touchscreen component – 480×272 A13-LCD7 – low-cost 7'' LCD display with optional touchscreen component – 800×480 A13-LCD10 – low-cost 10'' LCD display with optional touchscreen component – 1024×600 SATA-HDD-2.5-500GB – 5GB 2.5'' SATA hard disk SATA-CABLE-SET – cables that allow the connection of a 2.5'' hard disk to the board ALUMINIUM-HEATSINK-20×20×6MM – heatsink radiator for better processor heat dissipation

2.3 Powering the board

There are three possible ways of powering A20-OLinuXino-MICRO-4GB – via external supply providing 6-16V 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 consumes around 300mA of current at 12V when there are no peripherals connected to the USB hosts, so make sure the power supply is able to provide at least 500mA before plugging. 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. The best practice is not to count on the mini USB-OTG as a single power source!

The preferred way of powering the board is via the PWR jack with 6-16V DC with a power of 5W (e.g. 6Vx0.8A; 16Vx0.3A). This will 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 power provided might be insufficient to also power a bigger LCD connected to the LCD_con. However, this power option is capable of

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driving the board when using external display connected to the HDMI connector.

The typical consumption of A20-OLinuXino-MICRO-4GB is between 100mA and 320mA depending on the current load and the power voltage applied.

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_BUT 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.

2.4 Prebuilt software

The 4GB board-variant comes with Android 4.2.2 ready to use. The default settings of the software are followed. The default image works with HDMI monitor and 7'' display.

How we have installed the software? Detailed information might be found in chapter 6.1.1 USB-

OTG communication (NAND firmware repair/update).

2.5 Changing the default image resolution

Depending on the display or the screen you want to use with the A10-OlinuXino-LIME, you might need to apply software changes to the prebuilt Android or Linux image.

Generally, this means that 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

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

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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-MICRO.

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_OLinuXino.sh

and choose the resolution and the interface (LCD, HDMI or VGA).

The supported resolutions are:

For LCD:

1. 4.3" (480×272)

2. 7" (800×480)

3. 10" (1024×600)

For HDMI:

0. 480i

1. 576i

2. 480p

3. 576p

4. 720p50

5. 720p60

6. 1080i50

7. 1080i60

8. 1080p24

9. 1080p50

10. 1080p60

For VGA: (note that the VGA signals are routed to custom 6 pin connector and you need to from adapter to standard VGA connector, Olimex also sells such adapter cables)

0. 1680×1050

1. 1440×900

2. 1360×768

3. 1280×1024

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4. 1024×768

5. 800×600

6. 640×480

7. 1920×1080

8. 1280×720

2.6 Calibrating a display

2.6.1 Android calibration

Calibrating a display under Android is pretty straightforward from the Android application.

Important: initially the boards are calibrated for a specific display. If you re-write the image (no matter whether the SD card or the NAND memory) you would need to use a mouse to calibrate the display initially. It might be impossible to calibrate it via touching the display.

2.6.2 Debian calibration

The command for display calibrating in Debian Linux is:

ts_calibrate

The default Debian setup is made with settings for HDMI 720p/60Hz. If you want to change some other LCD, VGA or HDMI resolution then you have to start script file in /root directory.

If the problem is under Debian Linux make sure you are properly logged in the XFCE interface! Else applying calibration would not happen for the current user – if you are calibrating from the X graphical interface make sure that you are logged as user “olimex” (if calibrating without the X, the user is “root”).

#su olimex

enter the password: olimex

calibrate the touch screen and reboot the board

#sudo reboot

2.7 Software support

We maintain Linux and Android images for SD card which might be downloaded for free and modified as the user wishes. The latest images and updates are featured at the wiki article of the device: https://www.olimex.com/wiki/A20-OLinuXino-MICRO.

2.8 Button functions and NAND image restore in Android

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

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PWR_BUT – 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 couple of seconds to perform each action

RESET – used for hardware reset of the board – it is not recommended RECOVERY – used to wake up the board from sleep

The following buttons represent functions in the Android (it is possible that not all Android applications take advantage of the buttons, in such case the button would serve no purpose for that application):

VOL+ – increases the volume VOL- – lowers the volume MENU – brings up the main menu SEARCH – brings up search feature HOME – shows the home screen; note that HOME is also used to enter bootloader mode for

firmware update

ESC – used to navigate away of a menu ENTER – to select a choice

It is not recommended to disconnect the power supply (either the USB or the power jack) before turning off the Android from the either the menus or by holding PWR_BUT system written on the NAND.

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CHAPTER 3: A20-OLinuXino-MICRO BOARD DESCRIPTION

3. Introduction to the chapter

Here you get acquainted with the main parts of the board. Note the names used on the board might differ from the names used below to describe them. For the actual names check the A20OLinuXino-MICRO board itself.

3.1 Layout (top view)

The picture below shows the initial revision of A20-OLinuXino-MICRO. Please note that the NAND memory is present only in the 4GB version of the board.

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OLIMEX A20-OLinuXino-MICRO User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual