A20-OLinuXino-MICRO
Open-source single-board
Android/Linux mini-computer
USER’S MANUAL
Document revision S, March 2018
Designed by OLIMEX Ltd, 2015
All boards produced by Olimex LTD are ROHS compliant
OLIMEX© 2018
A20-OLinuXino-MICRO user's manual
DISCLAIMER
© 2018 Olimex Ltd. Olimex®, logo and combinations thereof, are registered trademarks of Olimex Ltd. Other product
names may be trademarks of others and the rights belong to their respective owners.
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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OLIMEX© 2018
A20-OLinuXino-MICRO user's manual
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..........................................................................................7
1.5 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 Prebuilt software.................................................................................................................... 11
2.5 Button functions..................................................................................................................... 11
2.6 Interacting with the board....................................................................................................12
2.6.1 HDMI monitor..............................................................................................................................................12
2.6.2 VGA monitor.................................................................................................................................................13
2.6.3 SSH via mini USB cable in Debian.............................................................................................................13
2.6.4 SSH via Ethernet..........................................................................................................................................13
2.6.5 LCD display..................................................................................................................................................13
2.7 Changing the default image resolution................................................................................14
2.8 Connecting a display and calibrating touchscreen.............................................................16
2.8.1 Android toucshcreen calibration.................................................................................................................16
2.8.2 Debian touchscreen calibration...................................................................................................................16
2.9 GPIO under Debian...............................................................................................................17
2.10 I2C and SPI under Debian..................................................................................................18
2.11 Software support..................................................................................................................18
CHAPTER 3: A20-OLINUXINO-MICRO BOARD DESCRIPTION.................19
3. Introduction to the chapter.....................................................................................................19
3.1 Layout (top view)...................................................................................................................19
3.2 Layout (bottom view).............................................................................................................20
CHAPTER 4: THE ALLWINNER A20 EMBEDDED PROCESSOR.................21
4. Introduction to the chapter.....................................................................................................21
4.1 The processor......................................................................................................................... 21
4.2 Block diagram........................................................................................................................ 22
CHAPTER 5: CONTROL CIRCUITY................................................................... 23
5. Introduction to the chapter.....................................................................................................23
5.1 Reset........................................................................................................................................23
5.2 Clocks......................................................................................................................................23
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OLIMEX© 2018
A20-OLinuXino-MICRO user's manual
5.3 Power supply circuit.............................................................................................................. 23
CHAPTER 6: CONNECTORS AND PINOUT......................................................24
6. Introduction to the chapter.....................................................................................................24
6.1 Communication with the A20............................................................................................... 24
6.1.1 USB-OTG communication (NAND firmware repair/update)..................................................................24
6.1.2 UART0, UEXT1, UEXT2 interface............................................................................................................26
6.2 SD card connectors................................................................................................................27
6.2.1 SD/MMC1 slot..............................................................................................................................................28
6.2.2 SD/MMC slot................................................................................................................................................29
6.3 PWR jack................................................................................................................................30
6.4 MIC_IN & HEADPHONES connectors..............................................................................30
6.5 USB_OTG connector.............................................................................................................31
6.6 USB_HOST connector...........................................................................................................33
6.7 Ethernet.................................................................................................................................. 34
6.8 HDMI connector.................................................................................................................... 36
6.9 VGA connector.......................................................................................................................37
6.10 SATA connector and power.................................................................................................38
6.11 GPIO ports............................................................................................................................39
6.11.1 GPIO-1 (General Purpose Input/Output) 40pin connector**................................................................39
6.11.2 GPIO-2 (General Purpose Input/Output) 40pin connector....................................................................40
6.11.3 GPIO-3 (General Purpose Input/Output) 40pin connector....................................................................41
6.12 LCD_CON 40pin connector................................................................................................43
6.13 Jumper description..............................................................................................................44
6.14 Additional hardware components...................................................................................... 45
CHAPTER 7: SCHEMATICS..................................................................................46
7. Introduction to the chapter.....................................................................................................46
7.1 Eagle schematic......................................................................................................................46
7.2 Physical dimensions...............................................................................................................47
CHAPTER 8: REVISION HISTORY AND SUPPORT........................................ 48
8. Introduction to the chapter.....................................................................................................48
8.1 Document revision................................................................................................................. 48
8.2 Board revision........................................................................................................................ 50
8.3 Useful web links and purchase codes...................................................................................52
8.4 Frequently asked questions (FAQ).......................................................................................53
8.5 Product support..................................................................................................................... 56
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OLIMEX© 2018
A20-OLinuXino-MICRO user's manual
CHAPTER 1: OVERVIEW
1. Introduction to the chapter
Thank you for choosing this A20 single board computer from Olimex! This document provides a
user’s guide for the Olimex A20-OLinuXino-MICRO 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 allows evaluation of the A20 processor,
manufactured by Allwinner Technology from China. The board is suitable for research and
development, but it can also be embedded in own products.
OLinuXino is an open-source, open-hardware project and all documentation that we used to
manufacture the board 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):
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A20 Cortex-A7 dual-core ARM Cortex-A7 CPU and dual-core Mali 400 GPU
1GB DDR3 RAM memory
4GB or 8GB NAND FLASH memory (available only on certain variants of the board)
4GB eMMC memory (available only on certain variants of the board)
Industrial temperature range versions available (boards with “-IND” suffix)
SATA connector with 5V SATA power jack
Capable of FullHD (1080p) video playback
Native HDMI output with connector; VGA output on 6-pin 1.25mm (0.05'') step connector
2 x USB High-speed host with power control and current limiter
USB-OTG with power control and current limiter
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 displays 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
Battery charge status LED and GPIO LED
2KB EEPROM for MAC address storage and more
10 BUTTONS with ANDROID functionality + RESET button
4 mount holes
Power jack for external power supply (7-24)V DC
1
PCB dimensions: (5600×3250) mils ~ (142.24×82.55) mm
For boards revision J or newer; the voltage applied to the power jack should be (6-16)V for older board revisions
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