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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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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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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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 DC1
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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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. The presence of native SATA and Ethernet controller and built-in battery charger
circuit allows the development of a wider range of products, compared to typical embedded Linux
boards. The A20-OLinuXino-MICRO is a mature product – a lot of experience and projects are
already available such as GPIO, UART, I2C, SPI, CAN libraries and examples. The A20 chip is also
very well known and well supported (including in mainline u-boot and kernel).
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
The board has six board variants. The base version of the board, that comes with NO extra flash
memory, and works in the commercial temperature range is named A20-OLinuXino-MICRO. The
base version is usually sufficient for research and development (unless your project specifically
requires industrial temperature range and extra flash memory storage).
You might find a comparison table of the different board variants below:
Extra
flash
Type of
flash
Size of
flash
Boot Linux from flash
memory
Operating
temperature
range
A20-OLinuXino-MICRO
No
-
-
-
0°C – 70°C
A20-OLinuXino-MICRO-IND
No
-
-
-
-40°C – 85°C
A20-OLinuXino-MICRO-e4GB
Yes
eMMC
4GB
Yes, after install script
0°C – 70°C
A20-OLinuXino-MICRO-e4GB-IND
Yes
eMMC
4GB
Yes, after install script
-40°C – 85°C
A20-OLinuXino-MICRO-n4GB
Yes
NAND
4GB
Yes, after install script
0°C – 70°C
A20-OLinuXino-MICRO-n8GB
Yes
NAND
8GB
Yes, after install script
0°C – 70°C
Board variant
The different versions of the boards can be determined by the suffixes after the base A20OLinuXino-MICRO name, different names determine different version. The suffixes indicate three
things:
i) type of flash (“e” stands for eMMC; “n” stands for “NAND”; if there is flash memory at all)
ii) size of flash (“4GB” or “8GB”)
iii) whether the board uses industrial temperature grade components (when “IND” suffix is present)
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The prices for different board versions are also different. These four versions with extra flash
memory are named: A20-OLinuXino-MICRO-e4GB, A20-OLinuXino-MICRO-e4GB-IND,
A20-OLinuXino-MICRO-n4GB, and A20-OLinuXino-MICRO-n8GB. The name consists of the
type of the memory and the size of the memory – suffix “e4GB” stands for eMMC type of flash
with 4GB of size; “n4GB” stands for NAND type of flash with 4GB of size; “IND” stands for a
board with industrial temperature range components.
The other Olimex boards with close characteristics are the ones with A13 and A10 microcontrollers.
The A13 boards feature a generation older processor but since they have been longer on the market
they might have better Linux and Android support. The A10 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. A more powerful chip than the A20 is used in the design of
A64-OLinuXino.
For projects and designs that require smaller form factor good alternatives to A20-OLinuXinoMICRO are: A20-OLinuXino-LIME2, A20-OLinuXino-LIME, A20-SOM-EVB, A20-SOM204EVB. For more powerful and recent designs consider the A64-OLinuXino board.
1.4 Board version used in the manual
Board from revision J was 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:
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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 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
This product 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 insulation products like USB-ISO to save your development board from potential over
voltage.
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.
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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 – (7-24)V DC2, 5W(10V @ 0.5A) required – for optimal power;
- 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-OLinuXinoMICRO
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
LCD-OLinuXino-4.3TS – low-cost 4.3'' LCD display with touchscreen component – 480×272
LCD-OLinuXino-7TS – low-cost 7'' LCD display with touchscreen component – 800×480
LCD-OLinuXino-10TS – low-cost 10.1'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6 – low-cost 15.6'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6FHD – low-cost 15.6'' LCD display with touchscreen component –
1920×1080
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
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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2.3 Powering the board
There are four possible ways of powering A20-OLinuXino-MICRO – via external supply providing
7-24V DC3 at the power jack, from 5V USB port via USB_OTG connector, from 3.7V Li-Po battery
via the LIPO_BAT connector, from 5V source applied to 5VEXT test pad at the bottom of the board
and any GND. 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.
The preferred way of powering the board is via the PWR jack with 7-24V DC with a power of at
least 5W (usually 6Vx1A, 12Vx0.5A, etc.). This will make the board fully powered and able to
power all the peripherals connected to it.
Important: Not all USB ports would be able to provide enough power for the board. Try using
another USB port or a cable of higher quality. If you have to use USB for powering, consider
externally powered USB port. The best practice is not to count on the mini USB-OTG as a single
power source!
The absolute maximum current available for the board and peripherals when the power supply is
supplied via USB-OTG connector is 900mA (no matter how much current you have available,
AXP209 would output no more than 900mA). Of course, a big part of the current is required for the
board itself (without anything extra attached)! For comparison, when the power jack is used to
power the board – the typical current available after the AXP209 is 2500mA!
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
driving the board when using external display connected to the HDMI connector.
The typical consumption of A20-OLinuXino-MICRO 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.
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.
3
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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2.4 Prebuilt software
The boards comes with no software uploaded. The board versions with extra flash memory also
come blank. Typically, the boards with NAND flash memory have the boot regions fixed, allowing
easier Linux install (eMMC boards don't need such preparation).
You can download the latest Linux Debian or Android image from the wiki article of the board and
download it to a microSD card. You can also install the Linux to the flash memory via install script.
If your board has extra flash memory and you want to boot Android from it refer chapter 6.1.1
USB-OTG communication (NAND firmware repair/update).
The default super user and password combination for the official Linux images is: “root” –
”olimex” and the GUI runs under user “olimex” with password “olimex”.
2.5 Button functions
The bellow three buttons usually are supported under both Android and Debian:
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 to reset the board this way;
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. This might lead to file
system corruption and would require re-writing the image on the flash memory.
How to restore the Android image might be found in chapter “6.1.1 USB-OTG communication
(NAND firmware repair/update)”.
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2.6 Interacting with the board
The typical and recommended way of interacting with a stand-alone A20-OLinuXino-MICRO
board is via a 3.3V serial-to-USB cable connected to a personal computer. Such cables are common
and easy to find. Olimex also distributes such cables. Even if you already have such a cable or you
decide to purchase it elsewhere it is advisable to check these product pages as a reference:
https://www.olimex.com/Products/Components/Cables/USB-Serial-Cable/USB-Serial-Cable-F/
https://www.olimex.com/Products/Breadboarding/BB-CH340T/open-source-hardware
You need to connect the serial cable lines as follows: RX line to UART0-TX pin; TX line to
UART0-RX pin; GND to GND. 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.
After everything else is set, you would need to power the board as explained in “2.3 Powering the
board”.
In addition to the serial communication, you might also use one or more of the following mediums
to interact with the board:
1. a monitor via HDMI connector
2. a monitor via the VGA connector and a VGA adapter
3. SSH via the mini USB connector trough a mini USB cable
4. SSH with a remote computer via LAN connector
5. a display via LCD_CON connector
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 latest official Debian Linux 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 medium. In
such cases, you can always use the serial-to-USB cable as a reliable way to establish connection to
the board.
2.6.1 HDMI monitor
All official Debian and Android images for A20-OLinuXino-MICRO have HDMI output by default.
The board would work out-of-the-box with a native HDMI monitor.
Make sure to use a tested HMDI cable.
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.
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More information about the video output settings and the usage of video settings script might be
found in the next chapter “2.7 Changing the default image resolution”.
2.6.2 VGA monitor
All official Debian images for A20-OLinuXino-MICRO have the option to for VGA video output
via the 6-pin VGA connector. If you wish to transform the custom 6-pin connector to a standard 15pin VGA connector you can either use wires or get a ready adapter called “A20-VGA-CABLE”.
More information about the video output settings and the usage of video settings script might be
found in the next chapter “2.7 Changing the default image resolution”.
2.6.3 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
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.
2.6.4 SSH via Ethernet
By default the board requests IP address from the network's DHCP server. You need to find what IP
address was assigned to the board before being able to access it over the network. Knowing the IP
address assigned allows you to connect to the board using an SSH client (for example “puTTY”)
then you have to use this address. You can change this policy or the address by editing
/etc/network/interface file.
Note that for internet connection you have to set your gateway address in /etc/network/interfaces
file and you have to set your DNS server in /etc/resolv.conf (for example “nameserver
192.168.1.1”)
2.6.5 LCD display
One of the ways to interact with the board is via an external display (with or without touchscreen
component). The 40-pin male connector LCD_CON has the typical 0.1'' pin step. All Olimex
displays have corresponding 40-pin male connector. You would only need a 0.1'' female-female
cable for the hardware connection.
In order to get the video output on the LCD display you might need either to run at least once a
configuration script (if you use Debian Linux) or download a suitable image (if you use Android).
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Video output settings are hard-coded in Android images
More information about the video output settings and the usage of video settings script might be
found in the next chapter “2.7 Changing the default image resolution”.
2.7 Changing the default image resolution
Depending on the display or the screen you want to use with the A20-OlinuXino-MICRO, 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-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
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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
4. 1024×768
5. 800×600
6. 640×480
7. 1920×1080
8. 1280×720
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 enabled.
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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2.8 Connecting a display and calibrating touchscreen
One of the ways to interact with the board is via an external display (with or without touchscreen
component). The 40-pin male connector LCD_CON has the typical 0.1'' pin step. All Olimex
displays have corresponding 40-pin male connector. You would only need a 0.1'' female-female
cable for the hardware connection.
All LCD displays made by Olimex have at least a 0.1'' LCD connector. Going for an LCD output
you would also need need and a cable to attach the display to the board. The cable is sold separately.
After the hardware connection is established, you need to execute shell script that would change the
video output of the board to fit the screen (refer to previous chapter).
The displays recommended for the board at the moment of writing might be found in the table
below:
Display name
Size of
display
in inches
LCD-OlinuXino-4.3TS 4.3
LCD-OLinuXino-7
7
LCD-OLinuXino-7TS
7
LCD-OLinuXino-10
10.1
LCD-OLinuXino-10TS
10.1
LCD-OLinuXino-15.6
15.6
LCD-OlinuXino-15.6FHD 15.6
Native
resolution
in pixels
480×272
800×480
800×480
1024×600
1024×600
1366×768
1920×1080
Official
Debian image
support
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Official
Android image
support
No
Yes
Yes
Yes
Yes
No
No
Link to product
page
Product
Product
Product
Product
Product
Product
Product
page
page
page
page
page
page
page
The displays whose names contain “TS” - include a resistive touch screen component.
The cable used for connection depends on the specific board you are using and more specifically it
depends on the pitch of the LCD connector of the board. We have two cables – both 40-pins ones
but one for the bigger pitch (0.1'') and the other for the smaller one (0.05''). Each of the displays
listed in the table above has two connectors suitable for both cables:
CABLE-IDC40-15cm – 15cm long cable suitable for 0.1'' step connectors – Product page
CABLE-40-40-10CM – 10cm long cable suitable for 0.05'' step connectors – Product page
2.8.1 Android toucshcreen calibration
Calibrating a touchscreen component under Android is pretty straightforward from the Android
application.
Important: initially the boards are calibrated for a specific display and resolution. If you re-write the
image (no matter whether the SD card or the NAND memory) you might need to use a mouse to
calibrate the display initially. It might be impossible to calibrate it only by using the touch
component over the display.
2.8.2 Debian touchscreen calibration
Navigate to the system menu and then select "Preferences" -> "Calibrate Touchscreen". Follow the
on-screen prompts and remember to save the settings in the xorg.conf.d folder as suggested.
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If there is no “Calibrate Touchscreen” tool, then you are using older official Linux image and you
should execute “ts_calibrate” command, logged as user “olimex” (“su olimex”). The password is
also “olimex”.
The touchscreen calibration under Debian is detailed in the following wiki article:
https://www.olimex.com/wiki/Touch_calibration_official_images
2.9 GPIO under Debian
You can read data from a given GPIO port. The logical ranges are usually as follows:
0V-1V for LOW (or 0)
2.4V-3.3V for HIGH (or 1)
All voltages are measured against ground (GND).
If the input signal is to high, you will at least destroy the port!
The algorithms for writing a value to a GPIO port and reading such a value are pretty similar. The
usage of GPIO ports follows the algorithm (we would use GPIO #49 for demonstration purposes):
1. Export GPIO 49:
echo 49 > /sys/class/gpio/export
Note that you can export GPIOs in range with:
for i in `seq 1 1 230`; do echo $i > /sys/class/gpio/export; done
2. Set input/output GPIO 49
2.1 Set input:
echo "in" > /sys/class/gpio/gpio49_ph9/direction
2.2 Set output:
echo "out" > /sys/class/gpio/gpio49_ph9/direction
3. Set value or read value GPIO 49
3.1 Set value:
echo 0 > /sys/class/gpio/gpio49_ph9/value
echo 1 > /sys/class/gpio/gpio49_ph9/value
3.2 Read input:
cat /sys/class/gpio/gpio49_ph9/value
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4. Unexport GPIO 49 when finished
echo 49 > /sys/class/gpio/unexport
A very good document on GPIO usage might be found here:
http://www.py6zgp.com/download/A20-GPIO.pdf – the document was created by Dr. Guido Pelz.
2.10 I2C and SPI under Debian
I2C and SPI are both supported in the latest Debian releases. There is respective kernel support for
both. There is a python module called pyA20 might be found here:
https://pypi.python.org/pypi/pyA20
At the same web address you would also find a set of examples on how module is used.
2.11 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.
We usually try to provide details on how to build the Linux and the Android images at our
wordpress page: http://olimex.wordpress.com/.
Another useful place is the Olimex forums where a lot of people share their experience and advice:
https://www.olimex.com/forum/
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).
You are more than welcome to send or share your suggestions and ideas at our e-mail, the public
forums or irc channel. We would attempt to help in almost every case. We listen to the feedback and
if the majority of users suggest a software change or update we try to implement such. Customer
feedback is very important for the overall state of the software support. However, do not expect full
Linux or Android software support.
We can share our experience. We can give you full details for things we have tried. We can point
you to a resource or a guide. We can give you general directions to solving a specific problem or
places to look for more information. However, we won’t install a piece of software for you or write
custom program for you. We won't provide a specific software solution to a specific software
problem.
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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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3.2 Layout (bottom view)
At the bottom of the board there are mainly buttons and the large SD/MMC connector.
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CHAPTER 4: THE ALLWINNER A20 EMBEDDED PROCESSOR
4. Introduction to the chapter
In this chapter is located the information about the heart of OLinuXino – its microcontroller. The
information is a modified version of the datasheet provided by its manufacturers.
4.1 The processor
The A20 chip is very popular and well-known. It has some features that are hard to find in similar
embedded chips – including SATA support and native EMAC and GMAC. The main feature of the
A20 processor is the sheer computing power that allows FullHD video playback. The graphical
processing unit is also pretty powerful and supported by the default software packages that come
with the OlinuXino boards. The software support for the features in the processor is at pretty good
state thanks to the efforts of the community and Allwinner themselves.
The full list of features might be found below:
CPU
ARM® Cortex™-A7 Dual-Core
GPU
ARM® Mali400MP2
Complies with OpenGL ES 2.0/1.1
VIDEO
HD H.264 2160p video decoding
Multi-format FHD video decoding, including Mpeg1/2, Mpeg4 SP/ASP GMC, H.263,
H.264,
VP6/8, AVS jizun, Jpeg/Mjpeg, etc.
H.264 High Profile 1080p@30fps or 720p@60fps encoding
3840×1080@30fps 3D decoding, BD/SBS/TAB/FP supported
Complies with RTSP, HTTP, HLS, RTMP, MMS streaming media protocols
DISPLAY
Supports multi-channel HD display
Integrated HDMI 1.4 transmitter with HDCP support
CPU/RGB/LVDS LCD interface
Supports CVBS/YPbPr/VGA
Integrated TV decoder
CAMERA
Integrated parallel 8-bit I/F YUV sensor
Integrated 24-bit parallel YUV 444 I/F
Supports 5M CMOS sensor
Supports dual sensors
MEMORY
DDR2/DDR3/DDR3L controller
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NAND Flash controller with 64-bit ECC
AUDIO
Integrated HI-FI 100dB Audio Codec
Dual analog mic amplifiers
More information can be found on Allwinner's web site at the following web-address:
http://www.allwinnertech.com/en/product/A20.html
4.2 Block diagram
The block diagram is taken from Allwinner's web-site.
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CHAPTER 5: CONTROL CIRCUITY
5. Introduction to the chapter
Here you can find information about reset circuit and quartz crystals locations, the power supply
circuit is discussed.
5.1 Reset
The board has hardware reset controlled by the AXP209 power system management IC.
The board should be turned off the standard OS menu (that might be invoked by holding POWER
button or “poweroff” command under Debian) and after the choice is confirmed it is safe to be
disconnected from the power supply unit.
5.2 Clocks
25 MHz quartz crystal Q1 is connected to pins X1 and X2 of the LAN8710A 100Mbit Ethernet
controller.
32 768 Hz (RTC) quartz crystal Q2 is found at pins F1 and F2 of the A20 microcontroller.
24 MHz quartz crystal Q3 is found at pins N22 and N23 of the A20 microcontroller.
5.3 Power supply circuit
The power supply is handled mainly by AXP209 power management system, an Allwinner chip that
goes together with the A20 processor. It is mounted on the board but since it is relatively hard to
find we also sell it separately.
The power supply circuit of A20-OLinuXino-MICRO requires input supply of 7-24V. The
minimum wattage is 5W, and this threshold may raise if using a lot of devices on the USB-HOST
(via external hub), a lot of GPIOs and the LCD_CON.
Important: Not all USB ports would be able to provide enough power for the board. Try using
another USB port or a cable of higher quality. If you have to use USB for powering, consider
externally powered USB port. The best practice is not to count on the mini USB-OTG as a single
power source!
The absolute maximum current available for the board and peripherals when the power supply is
supplied via USB-OTG connector is 900mA (no matter how much current you have available,
AXP209 would output no more than 900mA). Of course, a big part of the current is required for the
board itself (without anything extra attached)! For comparison, when the power jack is used to
power the board – the typical current available after the AXP209 is 2500mA!
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CHAPTER 6: CONNECTORS AND PINOUT
6. Introduction to the chapter
In this chapter are presented the connectors that can be found on the board all together with their
pinout and notes about them. Jumpers functions are described. Notes and info on specific
peripherals are presented. Notes regarding the interfaces are given.
6.1 Communication with the A20
The direct communication method is via the serial interface. Such interface is the UART0 connector
(five male pins pointing towards the edge of the board) capable of delivering some information on
the COM port of your computer – and then use your favorite terminal program (puTTy, teraterm,
etc) to receive the data/send commands. You can use USB-SERIAL-CABLE-F to interface UART0
– that allows you to debug the board with a personal computer with a free USB port.
If you decide to make your own cable you would need to consider that the levels at board's UART0
are in CMOS level (3.3V) and you would need a convertor to bring them to the TTL level of your
computer or cable! That is true for the RX and TX also!
It is highly recommended to own a USB-SERIAL-CABLE-F (or similar product) at hand when
debugging – the video output is not always reliable and if you set wrong display settings you might
be unable to recover the settings without a proper UART0 connection.
The more indirect ways of communicating with the board are via peripheral devices – mouse and
keyboard, via a touch screen LCD that is connected on LCD_CON connector and others.
6.1.1 USB-OTG communication (NAND firmware repair/update)
The main way of changing the firmware image located on the NAND of A20-OLinuXino-MICRO
is via the USB-OTG connector.
We have configured an Android image with settings suitable for A20-OLinuXino-MICRO. You can
upload it to the board with PhoenixSuit software via the USB-OTG. The image is available for
users to try and tweak the settings. The images can be downloaded from the wiki article at:
https://www.olimex.com/wiki/A20-OLinuXino-MICRO.
The board variant without NAND needs an SD card with bootable OS – Android or Linux. There
are ready images available for download at the above-linked A20 wiki article.
To repair the image on NAND re-upload it following these easy steps:
1. Install and run PhoenixSuit (can be found in the wiki article for A20).
2. Go to firmware tab of the program and point to a valid Android image (the latest official one may
also be downloaded from the A20 wiki article).
3. Disconnect the power supply and USB cable from the A20 board.
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4. Press and hold RECOVERY button, apply power supply (6-16)V, release RECOVERY button.
5. Connect USB cable to the mini USB connector
6. You will be asked for drivers for the bootloader. Navigate to the folder where you extracted the
PhoenixSuit and install the drivers from the respective executables (or manually point the installer
to the drivers folder in the PhoenixSuit installation path).
7. PhoenixSuit will detect the board and would ask for the method of writing the image. Choose
method of writing the image and confirm your wish to write the image.
8. Wait till upgrade succeeds as shown below:
There are different flavors of the Android and Linux distributions depending on whether you want
to use 50Hz HDMI or 60Hz HDMI or VGA or 7'' display or 10'' display etc. You might need to
change the configuration files inside (depending on your desirable output medium). How to do it is
explained in chapter 2.6 Calibrating a display.
Those images, the software required and further instructions might be found at the wiki page:
https://www.olimex.com/wiki/A20-OLinuXino-MICRO.
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6.1.2 UART0, UEXT1, UEXT2 interface
The UART0 might be used for UART communication by default. It is typically used for
serial/terminal debug. The UEXTs are typically used for connecting additional modules.
Note that by default only UART0 is defined as a port suitable for serial debug. You can use our
USB-SERIAL-CABLE-F for debugging. UEXT1 and UEXT2 are NOT defined by default.
Consider table below when connecting the USB-SERIAL-CABLE-F according to the wire color
code. The RX line of the cable (GREEN wire) should go to TX line of the target board; the TX line
of the cable (RED wire) should go to the RX line of the target board. The BLUE wire should go to
the target's GND line.
UART0
Pin # Signal name
Processor pin
1 3.3V
-
2 UART0-TX
A7
3 UART0-RX
B7
4 GND
UEXT1
Pin #
Signal name
Pin # Signal name
1 3.3V
2
GND
3 UART6-TX
4
UART6-RX
5 TWI2-SCK
6
TWI2-SDA
7 SPI2-MISO
8
SPI2-MOSI
9 SPI2-CLK
10
SPI2-CS0
UEXT2
Pin #
Signal name
Pin # Signal name
1 3.3V
2
GND
3 UART7-TX
4
UART7-RX
5 TWI1-SCK
6
TWI1-SDA
7 SPI1-MISO
8
SPI1-MOSI
9 SPI1-CLK
10
SPI1-CS0
The UEXT connectors are used as an interface for the Olimex's UEXT modules (usually boards
with MOD- prefix in their commercial names). For more information on UEXT please visit:
https://www.olimex.com/Products/Modules/UEXT/resources/UEXT.pdf
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6.2 SD card connectors
There are two SD card connectors on this A20 board. The now common microSD card connector is
located on the top of the board, near the audio in/out connectors.
Note that by default only the micro SD card slot might be used for booting the OS.
However, due to popular demand, there is also an SD/MMC card connector located on the bottom
of the board.
Both SD slots might be used simultaneously – there is no data multiplexing lines. For instance –
one of them might be used for booting the OS, the other – for storing data.
As a general precaution be careful with the SD cards you purchase. There is a big percentage of
fake cards due to the low effort required to counterfeit popular brands and the big demand for SD
cards worldwide. When in doubt – try the same operation with another card from another brand.
Olimex sells microSD cards with Linux or Android images, that have been tested – please refer to
chapter “2.2 Requirements”. Of course, if you already have a large enough microSD card you can
download the official Linux image from the wiki pages: https://www.olimex.com/wiki/A20OLinuXino-MICRO.
When removing the card, please make sure that you release it from the connector by pushing and
NOT by pulling the card directly (this can damage both the connector and the microSD card).
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6.2.1 SD/MMC1 slot
The schematic related to the SD/MMC1 (microSD connector) is shown below:
SD/MMC1 slot is the “smaller” microSD card slot, located on the top of the board.
This slot is typically used for booting the OS, due to the larger capacities of the microSD cards
(compared to SD or MMC cards). It is suggested to have an SD card with a proper Linux/Android
image especially if you have ordered a version of the board without NAND memory. It is also
recommended to use Class 10 (10MByte/sec) card for faster read/write operations, lower class cards
(especially higher capacity ones) might slow down the whole system.
microSD card connector
Pin # Connector signal name
Wire name (processor pin)
1 DAT2/RES
SD0-D2 (K19)
2 CD/DAT3/CS
SD0-D3 (K20)
3 CMD/DI
-
4 VDD
-
5 CLK/SCLK
SD0-CLK(L20)
6 VSS2
-
7 DAT0/DO
SD0-D0(M19)
8 DAT1/RES
SD0-D1(M20)
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6.2.2 SD/MMC slot
The schematic related to the SD/MMC1 (SD/MMC connector) is shown below:
The SD/MMC2 slot is located on the back of the PCB and works with the “larger” SD and MMC
cards. The connector was placed by a popular demand.
Note that by default this connector is not suitable for booting OS. Such support is possible but not
implemented in the official software releases.
SD/MMC card connector
Pin # Connector signal name
Wire name (processor pin)
1 CD/DAT3/CS
SDC3-D3 (B16)
2 CMD/DI
SDC3-CMD (A18)
3 VSS1
-
4 VDD
-
5 CLK/SCLK
SDC3-CLK (B18)
6 VSS2
-
7 DAT0/DO
SDC1-D0 (A17)
8 DAT1/RES
SDC1-D1 (B17)
9 DAT2/RES
SDC1-D2 (A16)
Additionally, there are the WP and CP switches that are responsible, respectively, for sensing
whether the card is locked for reading and whether there is a card inserted.
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6.3 PWR jack
The power jack used is the typical one used by Olimex in most of our products – the DC barrel jack
has 2.0mm inner pin and 6.3mm hole. More information about the exact component might be found
here: https://www.olimex.com/wiki/PWRJACK.
You should provide 6 to 16 volts direct current and the required current may vary depending on the
peripherals connected to the board. The power supply you use should be capable of providing at
least 500mA of current.
Pin #
Signal name
1
Power input
2
GND
More info about the power supply can be found in chapter 5 of this manual.
6.4 MIC_IN & HEADPHONES connectors
The part of the schematic related to those connectors is listed below:
Standard MIC_IN jack is mounted for audio input to the board. Note that it is a single channel
MIC_IN. The MIC_IN is a mono input.
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MIC_IN connector
Pin #
Signal name
Processor pin
2
MICIN
AC20
3
MICIN
AC20
5
GND
-
The socket can interface standard 3.5 mm phone connector (also known stereo plug or audio plug).
Headphones connector
Pin #
Signal name
Processor pin
2
HPOUTL
Y19
3
HPOUTR
W19
5
HPCOM (GND)
AA19, AA20
The connector can interface standard 3.5 mm phone connector (also known stereo plug or audio
plug).
The default audio output is set to the HDMI connector (for displays and monitors with built-in
audio speakers). If you wish to use audio out you need to first disconnect the HDMI, boot the board,
connect the audio out device (speakers) and finally connect the HDMI.
6.5 USB_OTG connector
The part of the schematic related to the USB_OTG is shown below:
The USB_OTG features Low Loss Power Distribution Switch SY6280 which protects the board in
case the devices you have plugged to the USB_OTG attempt to draw more current than 523mA
combined. The maximum current available on the 5V USB_OTG is exactly 523mA.
The SY6280 responsible for the USB_OTG is enabled by USB0-DRV (processor pin C12), thus the
USB_OTG is also controlled by the same signal.
There are two parts of a successful OTG device/host mode switch and usage – hardware part and
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software part.
The hardware part is the cable – to use the OTG as a host you would need a mini USB to USB
adapter cable. Do not confuse micro and mini USB!
The software part is loading a kernel module responsible for the behavior of the board while in
device mode. If such software is not enabled or missing in the official distribution – you would
need, respectively, either to load the module or rebuild the kernel to enable the module. There are
several modules that you might need depending on what your goals are.
USB_OTG connector
Pin #
Signal name
Processor pin
1
+5V_OTG_PWR
-
2
UDM0
N20
3
UDP0
N21
4
USB0-IDDET
B5
5
GND
-
The connector case is also grounded.
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6.6 USB_HOST connector
The part of the schematic related to the USB_HOST connector is listed below:
The USB_HOST connector features two levels – called USB1 and USB2 in the schematic. The
connector is situated between the USB_OTG and the HDMI connector. Each of slots them features
a low loss power distribution switch SY6280 which protects the board in case the devices you have
plugged to each level USB_HOST try to draw more than the allowed current.
Please note the pads of capacitors C222 and C223 where you can solder tantalum capacitors
(220uF/18V). If you do so you would be able to increase the stability of the powering by the USB
ports when the powered device has high current consumption.
The maximum current available on each slot of the 5V USB_HOST is different! USB1 is capable of
providing 1000mA of current; while USB2 is capable of providing only 523mA. If you have a
device that draws higher current please plug it into USB1.
The SY6280 responsible for the USB1 is enabled by USB0-DRV1 (processor pin A4).
The SY6280 responsible for the USB2 is enabled by USB0-DRV2 (processor pin A5).
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USB_HOST two-level connector
Pin # Signal name
Processor pin
Pin #
Signal name
Processor pin
1.1
5V
Connected to SY628
2.1
5V
Connected to SY628
1.2
UDM1
P20
2.2
UDM2
R20
1.3
UDP1
P21
2.3
UDP2
R21
1.4
GND
-
2.4
GND
-
The GND is common for both levels of the USB_HOST.
6.7 Ethernet
In different hardware revisions of the board we have used a number of different megabit Ethernet
controllers. This is why it is important to test with the latest official image first.
In hardware revision J of the board we switched to Microchip's LAN8710AI-EZK(QFN-32). Note
that the industrial version of the board uses industrial version of the chip. Make sure to refer to the
hardware schematic for exact information about the chip used.
If you have problems with the software support for the Ethernet in Linux, consider checking our
latest build instructions and patches. At the time of writing, a patch to get the Ethernet working can
be found here: https://github.com/OLIMEX/OLINUXINO/blob/master/SOFTWARE/A20/A20build-3.4.103-release-5/a20-phy_1000_100-dram.patch
If you use Linux then the Ethernet connector might be used for SSH connection to the board. If you
lack any other option for debugging it might be hard to guess the correct IP of the board since it has
DHCP enabled by default (especially if you are in a large network). It is good idea to check the
default settings by exploring the Linux image settings. Those are usually stored in:
/etc/network/interfaces
For DHCP you need to enable auto detection and dhcp as shown below:
auto eth0
iface eth0 inet dhcp
For setting a static address please follow the pattern below:
auto eth0
iface eth0 inet static
address 192.168.1.5
netmask 255.255.255.0
gateway 192.168.1.254
The EEPROM memory may be used to store the MAC address.
Important: In some Debian images it is possible that the Ethernet doesn't get auto-detected during
boot-up. This is done on purpose because if there is auto-detection enabled and you don't want to
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use the Ethernet connector or you have forgotten to plug a cable the start-up would be greatly
delayed. This might be problem in the first start-up to users counting only on SSH connection. You
can enable the Ethernet after a successful boot-up with:
ifconfing -a
dhclient eth#(as seen after after the ifconfing command)
Important: You can configure static/DHCP-given IP addresses in /etc/network/interfaces
Ethernet
Pin #
Signal name
1
TD+
2
TD-
3
VDD
4
NC
5
NC
6
VDD
7
RD+
8
RD-
LED
Color
Usage
Right
Green
Link status
Left
Yellow
Activity status
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6.8 HDMI connector
The part of the schematic that describes the HDMI module is shown below:
Note that there are different Linux images depending whether the HDMI TV works at 50Hz or
60Hz refresh rate. If you board runs Android there is a specific option to set the appropriate HDMI
output.
HDMI connector
Pin #
Signal name
Processor pin
1
HTX2P
T23
2
GND
3
Pin #
Signal name
Processor pin
11
GND
-
-
12
HTXCN
W22
HTX2N
T22
13
HCEC
P23
4
HTX1P
U23
14
NA*
NA
5
GND
-
15
HSCL
R23
6
HTX1N
U22
16
HSDA
R22
7
HTX0P
U23
17
GND
-
8
GND
-
18
+5V
-
9
HTX0N
U22
19
HHPD
P22
10
HTXCP
W23
*Pin 14 of the HDMI is not mandatory. In HDMI 1.0-1.3c it is reserved pin; in HDMI 1.4+ it is
optional.
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6.9 VGA connector
You would probably need an adapter cable for the VGA display (6-pin connector to 15-pin female
RGB cable). You can make the cable or the connection yourself or you can purchase the Olimexmade cable: https://www.olimex.com/Products/Components/Cables/A20-VGA-CABLE/. Note that
you also have to change the script under Debian as explained in chapter 2.6 “Calibrating a display”.
Please note that you would need a specific Android image for the VGA output (with proper display
and output settings). We don't provide such image ready at the moment!
The VGA output has been tested only with the official Debian Linux image so far and it works fine
(after selecting the proper mode by executing ./change_display*.sh).
VGA 6-pin connector
VGA 15-pin connector (back numbering)
Connector Signal name Processor pin
pin #
Connector pin #
(back numbering)
Color code (according
to the image below)
1
VGA-R
AC17
1
RED
2
VGA-B
AB16
3
BLUE
3
VGA-G
AC16
2
GREEN
4
VGA_VSYNC
AC9
14
BLACK
5
VGA_HSYNC
AB9
13
BROWN
6
GND
-
6
PINK
Back view of the 15 pin connector
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6.10 SATA connector and power
The part of the schematic describing the SATA module is shown below:
SATA connector
Pin # Signal name
Processor pin
1
GND
-
2
SATA-TXP
T20
3
SATA-TXM
T21
4
GND
-
5
SATA-RXM
U21
6
SATA-RXP
U20
7
GND
-
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6.11 GPIO ports
There are three GPIO ports which are used generally to access unused by the board's peripherals
pins. However, there are exceptions – some of the pins might be used to easily peripherals or their
levels.
Most of the pins are already defined in default operating system images. Some of them can be used
as GPIOs, I2C or SPI without much of a problem. Information on the software usage of GPIO ports
might be found in chapters “2.8 GPIO under Debian” and “2.9 I2C and SPI under Debian”.
6.11.1 GPIO-1 (General Purpose Input/Output) 40pin connector**
The GPIO-1 plastic connector has 14 pins. The signal layout is described below:
GPIO-1 connector
Pin # Signal name
Processor pin
Pin # Signal name
Processor pin
1 +5V
-
2 GND
-
3 +3.3V
-
4 GND
-
5 PG0
F20
6 VOL+_BUT
AB23***
7 PG1
E21
8 VOL-_BUT
AB23***
9 PG2
E20
10 MENU_BUT
AB23***
11 PG3
D21
12 SEARCH_BUT
AB23***
13 PG4
D20
14 HOME_BUT
AB23***
15 PG5
C21
16 ESC_BUT
AB23***
17 PG6
E19
18 ENTER_BUT
AB23***
19 PG7
C20
20 TVOUT3
AB17
21 PG8
D19
22 TVIN0
AC18
23 PG9
C19
24 TVIN1
AB18
25 PG10
D18
26 TVIN2
AA17
27 PG11
C18
28 TVIN3
Y17
29 VGA_HSYNC
AB9*
30 LINEINR
AB21
31 VGA_VSYNC
AC9*
32 LINEINL
AB20
33 VGA-G
AC16*
34 FMINR
Y21
35 VGA-B
AB16*
36 FMINL
Y20
37 VGA-R
AC17*
38 MIC1OUTP
AC22
39 LRADC1
AB22*
40 MIC1OUTN
AC23
*Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handled
properly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).
**It was erroneously named GPIO-4 in the first release of the board.
***All Android buttons are connected to an ADC (LRADC) that uses a divider to determine which button is pressed.
The yellow part of the table shows all the signals shared with the 6-pin VGA connector.
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6.11.2 GPIO-2 (General Purpose Input/Output) 40pin connector
The GPIO pins are led out on a separate 40pin connecter. They allow the user to attach additional
hardware, check readings or perform hardware debug. The GPIO-2 connector numbers are printed
at the bottom of the board for your convenience.
GPIO-2 connector
GPIO pin# Signal name
Processor pin#
GPIO pin#
Signal name
Processor pin#
1
5V
-
2
GND
-
3
3.3V
-
4
GND
-
5
TWI0-SCK
A15
6
PE0
E23
7
TWI0-SDA
B15
8
PE1
E22
9
PI0
A20
10
PE2
D23
11
PI1
B20
12
PE3
D22
13
PI2
A19
14
PE4
C23
15
PI3
B19
16
PE5
C22
17
PI10
C17
18
PE6
B23
19
PI11
D17
20
PE7
B22
21
PC3/NCE1
L22*
22
PE8
A23
23
PC7/NRB1
J22*
24
PE9
A22
25
PC16
M21
26
PE10
B21
27
PC17
F23
28
PE11
A21
29
PC18
F22
30
PI14
C15
31
PC23
G19
32
PI15
D15
33
PC24/NQS
F21*
34
UART0-RX
B7*
35
GPIO1
-
36
UART0-TX
A7*
37
GPIO2
-
38
NMI_N
F5
39
GPIO3
-
40
RESET_N
C14
Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handled
properly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).
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6.11.3 GPIO-3 (General Purpose Input/Output) 40pin connector
GPIO-3 connector features the signals of AXP152 on a convenient header. The signals available
might be used to implement power controls on the board – for instance – turning off the device at
specific voltage level or detecting levels.
The JTAG signals might also be accessed at this header.
GPIO-3 connector
GPIO pin# Signal name
Processor pin#
GPIO pin#
Signal name
Processor pin#
1
5V
-
2
GND
-
3
3.3V
-
4
GND
-
5
PH0
A6
6
PB3
B14
7
PH2/LED
C6
8
PB4
A13
9
PH7
B4
10
PB5
B13
11
PH9
D4
12
PB6
A12
13
PH10
A3
14
PB7
B12
15
PH11/SDC3-DET# B3*
16
PB8/SATA-PWR-EN
A11
17
PH12
C3
18
PB10
C11
19
PH13
A2
20
PB11
C10
21
PH14
B2
22
PB12
C9
23
PH15
A1
24
PB13
B11
25
PH16
B1
26
PB14
A10
27
PH17
C1
28
PB15
B10
29
PH18
C2
30
PB16
A9
31
PH19
D1
32
PB17
B9
33
PH20
D2
34
PH24
E3
35
PH21
D3
36
PH25
E4
37
PH22
E1
38
PH26
F3
39
PH23
E2
40
PH27
F4
Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handled
properly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).
The yellow part of the table shows the JTAG signals.
These signals might be conveniently accessed on GPIO-3 connector. These JTAG signals might be
found at processor port PB. The pins of the connector are respectively GPIO-3 #26; GPIO-3 #28;
GPIO-3 #30; GPIO-4 #32. More specifically:
PB14 – MS0 (TMS) - GPIO-3 #26
PB15 – CK0 (TCK) - GPIO-3 #28
PB16 – DO0 (TDO) - GPIO-3 #30
PB17 – DI0 (TDI) - GPIO-4 #32
You would also need Vdd and GND which might be found on various places on the board. This
information should be sufficient to establish a hardware connection. The connection would depend
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on the debugger you have and the type of its connector (20-pin JTAG, 10-pin JTAG, etc).
Software-wise – the JTAG should be enabled by default but you might also edit the script.bin/fex
file that contains special JTAG part. Please check here: http://linuxsunxi.org/Fex_Guide#.5Bjtag_para.5D; the [jtag_para] part.
The real issue would be finding piece of software that has Allwinner A20 support. The sunxi
community has some experimental configuration files for A10 and A13 boards I believe, but they
were never tested by an Olimex employee.
Furthermore, we have no experience with the JTAG debug, we have not performed any JTAG
debug sessions ourselves.
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6.12 LCD_CON 40pin connector
The LCD_CON pins are led out on a separate 40pin connecter for the ease of connecting an LCD.
We have tested the ability of the board to interact with such a display. They allow the user to attach
additional hardware, check readings or perform hardware debug.
Important: you need additional 40PIN ribbon cable to connect an Olimex display and the
LCD_CON.
LCD_CON connector
GPIO pin# Signal name Processor pin
GPIO pin#
Signal name
Processor pin
1
+5V
-
2
GND
-
3
+3.3V
-
4
GND
-
5
LCD_D16
Y12
6
LCD_D17
AA12
7
LCD_D18
Y11
8
LCD_D19
AA11
9
LCD_D20
Y10
10
LCD_D21
AA10
11
LCD_D22
AB12
12
LCD_D23
AC10
13
LCD_D8
AB11
14
LCD_D9
AC11
15
LCD_D10
Y15
16
LCD_D11
AA15
17
LCD_D12
Y14
18
LCD_D13
AA14
19
LCD_D14
Y13
20
LCD_D15
AA13
21
LCD_D0
AB15
22
LCD_D1
AC15
23
LCD_D2
AB14
24
LCD_D3
AC14
25
LCD_D4
AB13
26
LCD_D5
AC13
27
LCD_D6
AB12
28
LCD_D7
AC12
29
LCD_HSYNC
AB9
30
LCD_VSYNC
AC9
31
LCD_CLK
Y9
32
LCD_DE
AA9
33
PB3**
B14
34
PB4**
A13
35
LCD_PWR
C4
36
PB2/PWM0
A14*
37
TPX1
Y22
38
TPX2
AA22
39
TPY1
Y23
40
TPY2
AA23
Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handled
properly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).
**Pins 33 and 34 are disconnected by default. You need to place the two resistors marked as NA to establish connection to
processor's PB3 and PB4.
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The LCD connector is suitable for a number of Olimex displays and touchscreen panels with
different native resolution – the smallest available is the 4.3'' one called LCD-OLinuXino-4.3TS
with native screen resolution of 480×272, through the 7'' one named LCD-OlinuXino-7TS with
800×480, to the 1024×600 10.1'' LCD-OLinuXino-10TS.
IMPORTANT:
You need to upload new Android image to the board. These images are available here:
https://www.olimex.com/wiki/A20-OLinuXino-MICRO (using an operating system – NAND flash).
In Debian Linux you would need to start a start a shell script to change the built-in the image
resolution settings. Start it with ./change_display_A20_OLinuXino.sh and follow the instructions.
Please refer to chapter 2.5 “Changing the default image resolution” for more details.
6.13 Jumper description
Please note that most the jumpers on the board are SMT type. If you feel insecure of your
soldering/cutting technique it is better not to try to adjust the jumpers since it is possible to damage
the board.
Board jumpers
Jumper name
Type
Default position
Function
NAND_E
PTH
UBOOT
Changes the functionality of the
BOOT/REC button – when in UBOOT
position the button is used to
enter bootloader mode (to connect
via USB_OTG). When in REC
VPS-
SMT
Open
Reserved for future use of
different types of NAND memories.
VPS+
SMT
Open
Reserved for future use of
different types of NAND memories.
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6.14 Additional hardware components
The components below are mounted on OLinuXino but are not discussed above. They are listed
here for completeness:
Reset button – used to reset the board
1GB = 2×[4Gb(256M x 16b)] DDR3 SDRAM – the exact memories varies between the hardware
revisions of the board (also the -IND industrial version uses industrial memories). Refer to the
schematic of your board for details on the exact memory.
The DDR3 memory part name in the schematic might be outdated. We have used a number of
different but fully compatible DDR3 memories due to supply unavailability. It is always
recommended to check the exact memory name printed on the component itself.
4GB =1×[32Gb(4096M x 8b)] eMMC FLASH – only available on the 4GB version of the board;
the exact memory used varies between hardware revisions of the board. Refer to the schematic of
your board for details on the exact memory.
PWR_LED – turns on upon powering the board
LED1 – GPIO button
CHGLED – lights when charging a battery connected to the Li-Po battery connector.
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CHAPTER 7: SCHEMATICS
7. Introduction to the chapter
In this chapter is located information about the schematics describing logically and physically A20OLinuXino-MICRO.
7.1 Eagle schematic
OLinuXino schematics may be found it on the OLinuXino's GitHub repository:
https://github.com/OLIMEX/OLINUXINO/tree/master/HARDWARE/A20-OLinuXino-MICRO.
You can download the whole repository as .zip without having a GitHub account.
Please note that the schematics of A10 (not to be confused with A10s) and A20 boards are the same
since the two Allwinner processors are pin-to-pin compatible (drop-in replaceable). This means that
schematics for older hardware revisions of A20-OLinuXino-MICRO can be found in the GitHub
folder for A10-OLinuXino-MICRO.
We mostly use Eagle by Cad Soft 4.16r2 for designing. However, the files should be compatible
with the latest Eagle available. Cad Soft offers a trial version of their software that allows you to
inspect schematics and board files (without being able to modify them).
This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License.
To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/.
If you are looking for a schematic of an older revision of the board and it isn't available at our web
site you may request it by the support e-mail.
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7.2 Physical dimensions
Note that all dimensions are in mils.
The three highest elements on the board in order from the tallest to the shortest are: USB_HOST
connector – 700mils, capacitors C202 – 650mils, the Ethernet connector – 600mils.
The heights listed above include the PCB height.
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CHAPTER 8: REVISION HISTORY AND SUPPORT
8. Introduction to the chapter
In this chapter you will find the current and the previous version of the document you are reading.
Also the web-page for your device is listed. Be sure to check it after a purchase for the latest
available updates and examples.
8.1 Document revision
Revision, date
A, 30.08.13
B, 16.09.13
C, 18.09.13
D, 30.09.13
E, 02.10.13
F, 16.10.13
G, 24.10.13
H, 27.05.14
Notable changes
Modified page
Initial manual release
All
1. Quartz values error fixed
15
2. Updated the board revision changes 16
1. Added new additional products
9
2. Added more information about the 43
SD card booting
1. Added few suggestions for USB boot
2. Added more information about power
9
saving mode before complete Android
booting
1. Added more information about
11
display setting
2. Added chapter about the VGA
29
3. Added FAQ section
42
Added more information about A20-VGAMultiple pages
CABLE
1. Added more information about SSH 27
connection
2. Added more information about VGA 29
output requirements
3. Improved the FAQ section
41
1. Added more information about USB
10
host ports
2. Added new information for latest
41
board revisions
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OLIMEX© 2018
Revision, date
I, 30.05.14
J, 03.11.14
K, 30.01.2015
L, 09.02.2015
M, 10.02.2015
N, 16.02.2015
O, 16.03.2015
P, 23.12.2015
Q, 17.05.2017
R, 29.09.2017
S, 26.10.2017
A20-OLinuXino-MICRO user's manual
Notable changes
Modified page
1. Updated pictures with revision E 1, 14, 15
2. Updated document information to
reflect the changes in the board
26, 27
3. Adjusted several paragraphs and
tables
Multiple pages
1. Expanded GPIO-3 chapter by adding
JTAG information
2. Added GPIO, I2C and SPI sections
3, 13, 14, 34, 35, 36,
3. Added information about newer
37, 44
Olimex A20 boards boards
4. Added board revision G changes
5. Fixed few spelling mistakes
1. Updated list of suggested displays
8, 27, 46
2. Fixed error about the power jack
Fixed information about the CMOS-TTL
convertor
Added chapter “2.6 Interacting with the
board”
1. Information about the Windows driver
for the tethering
2. Clarified how to prepare a microSD
card with Android OS
Updated HDMI parts to reflect the latest
schematic
1. Clarified that we no longer load
Android on the 4GB version of the board;
2. Added information about Debian
nandinstall
Added information about new hardware
revisions and versions of the board.
Mentioned the change to new Ethernet PHY
controller.
Added info about new board variants
Changed external power supply
requirement to 7-24V; updated numerous
old articles
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21
11
12
52
5, 36
All
All
6, 7
All
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8.2 Board revision
Remember to check the schematics and the board design files to compare the differences.
Revision
B
C
Notable changes
Initial release of the board
1. Resistor matrix RM23 gets replaced by: R133,R134,R135
2. Adjusted the package of H5TQ2G63BFR/MEM4G16D3EABG-125
3. R12 and R15 values changed to 0R
4. NAND_E jumper is changed from PTH to SMD closed
5. 5V_SATA_PWR connector (altogether with 2×2uF) is changed from
WF2S to DW02S and placed near the PWR jack instead of original
position
6. GPIO-4 is now correctly named GPIO-1
7. There is a signal for the power of of the SATA – PB8/SATA-PWR-EN
(r136, c216, r138, t1, t137, fet4)
8. A jumper between 5V_E_SATA and 5V_PWR_SATA is added
9. The micro SD card connector is changed
D
Resistor optimizations
E
1. Adjusted and optimized the position of PCB names
2. R16 changed from 237R to 330R, for stability purposes
3. R7, R9 also changed from 237R to 330R, for stability purposes
4. R41 and R104 changed from 1k/1% to 390R for better sync signal
and to improve the VGA signal (allowing it to work at FullHD)
F
G
H (unreleased)
1. Added 10M resistor in parallel to 32768 crystal else there might
be hang-ups
2. Changed to 32768 crystal to SMD one
3. Few libraries updated
4. Added pads of two tantalum capacitors C222 and C223 near the
USB-host
5. Positions adjusted – A20, NAND, SPIFLASH, LAN, matrix,
capacitors, CARDs and other
6. Added tantalum capacitor 220uF/10V to ISPOUT
7. R48(13k/1%) changed to 6.8k/1% so there would be 1A of current
on USB1; USB2 still gets 523mA maximum
1. Added a 220uF/tant to SATA PWR
2. C216 changed from 100n to 22uF/6.3V, this improves hard-disk
switching on
3. Update of all component libraries. HDMI connector is changed to
a new package.
4. Now not placing ESD protection buffers due to hardware
difficulties with their placement
1. Changed the LAN part of the design, added two capactiors
1nF/2kV/X7R/1206, and 1nF/2kV/X7R/1206_or_1M, also the matrix is
now 0402 with 49.9 ohm at 1%.
2. Major polygon changes.
3. Removed HDMI protection circuit(RCLAMP0524P becomes NA).
4. Preparation for memory changes from MEM4G16D3EABG-125 to
K4B4G1646D-BCK0.
5. Position of C95 and C96 slightly adjusted, so that they are not
under GPIO-1 and LAN. USB_OTG polygon changed. USB_HOST polygon
adjusted. Removed few viases.
6. Added few more vias for the VCC.
7. Improved white print. Year and revision updated. Web-site
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address updated.
8. Power jack package updated.
9. SATA package updated.
I (unreleased)
1. eMMC was added.
2. RTL8201CP(LQFP-48) Ethernet chip replaced with LAN8710AIEZK(QFN-32). Both are MbE PHYs.
3. All libraries were updated.
4. L7, L15, L16 and L17 were changed from FB0805/600R/200mA(201209601) to FB0805/600R/2A.
5. PWR-JAKPWR_JACK_UNI_MILLING_SMALLER_DRILLS changed to PWRJ2mm(YDJ-1136).
6. R98 optimized from 10k/1% to 10k.
7. C195 and C208 optimized 22pF to 33pF.
8. R43 and R103 optimized from 51R to 100R.
9. C123, C126 and C135 were changed from
100uF/16V/LOWESR/105C/6.3x11mm_RM2.5 to 2x47uF/6.3V/0805, i.e.
C123||C240, C126||C222 and C135||C223
10. D6 was renamed to D2 and changed to the D4's package.
11. U13 and U15 were changed from SY8008 to SY8009AAAC(SOT23-5).
12. ODT1, SCKE1, SCS1/SA15 and ZQ1 were connected to the 2 DDR
memories with aim to support bigger sizes if one day A40 is
released or A10 is used.
13. All resistor matrices: RM1-RM8 and RM16RM21(RA0805_(4X0402)_0R(Board_Mounted)) were removed and the wires
were shortened. The same thing was done for: R106R117(0R(Board_Mounted)).
14. The viases that were between GPIO-1 pads 12/14 were removed.
15. The eMMC was placed over the NAND flash.
16. The cream layer was improved.
17. BKUP connector(HN1x2) was added for AXP's power management
option.
18. RM1 and RM2 were added to enable CTP support for the LCD
connector.
19. MP1482DS was exchanged with MP1584EN(SOIC8E). Because of this,
were affected D5, C202, C203 and several other components as well.
20. The files were renamded from 4G to nothing, because the
schematic is universal for all boms generated!
21. C217's value was changed from 220uF/10V/TANT to
220uF/10V/TANT_D!
22. Added reset control for the new PHY – C63 becomes NA down from
10uF, R26 becomes NA down from 10K and R25 is now 100R up from NA.
J (released)
1. Rotated RM1 and RM2 at 90 degrees for better soldering.
2. Created separate design for each of the variants of the board
(1. commercial temperature range and no flash memory – A20OLinuXino-MICRO; 2. industrial temperature range and no flash
memory – A20-OLinuXino-MICRO-IND; 3. commercial temperature range
and flash memory – A20-OLinuXino-MICRO-EMMC; 4. industrial
temperature range and flash memory – A20-OLinuXino-MICRO-EMMC-IND)
- each of these boards would have own hardware revision from now
on.
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8.3 Useful web links and purchase codes
The web pages you can visit for more information about your device are:
https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXino-MICRO-4GB/;
https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXino-MICRO/.
The wiki article for the board: https://www.olimex.com/wiki/A20-OLinuXino-MICRO
A place for general questions, FAQ or friendly talk: https://www.olimex.com/forum/.
You can get the latest updates on the software at: https://github.com/OLIMEX/OLINUXINO.
You may may join our IRC channel #olimex @ freenode.net (http://webchat.freenode.net/?
channels=olimex).
ORDER CODES:
A20-OLinuXino-MICRO – the base version of A20-OLinuXino-MICRO, suitable for commercial
temperature range and no external NAND
A20-OLinuXino-MICRO-IND – industrial version (with extended operating temperature range) –
has industrial versions of RAM memory and Ethernet controller
A20-OLinuXino-MICRO-e4GB – A20-OLinuXino-MICRO with additional 4GB eMMC memory
A20-OLinuXino-MICRO-e4GB-IND – an industrial version of A20-OLinuXino-MICRO with
additional 4GB eMMC memory
A20-OLinuXino-MICRO-n4GB – a version of A20-OLinuXino-MICRO with additional 4GB
NAND memory
A20-OLinuXino-MICRO-n8GB – a version of A20-OLinuXino-MICRO with additional 4GB
NAND memory
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 standard 15-pin VGA one
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-OLinuXinoMICRO
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
LCD-OLinuXino-4.3TS – low-cost 4.3'' LCD display with touchscreen component – 480×272
LCD-OLinuXino-7TS – low-cost 7'' LCD display with touchscreen component – 800×480
LCD-OLinuXino-10TS – low-cost 10.1'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6 – low-cost 15.6'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6FHD – low-cost 15.6'' LCD display with touchscreen component –
1920×1080
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How to purchase?
You can purchase directly from our online shop or from any of our distributors. List of confirmed
Olimex LTD distributors and resellers: https://www.olimex.com/Distributors.
Please visit https://www.olimex.com/ for more info.
8.4 Frequently asked questions (FAQ)
Q: I power my board, it shows a logo and then nothing happens.
A: This might be due to a number of reasons but it is recommended to try the following:
1. Download latest official image from our wiki (either Android or Debian; either for SD card or
flash memory), and upload it to the flash or to an SD card again. There are instructions how to do it
in the other questions below. Try if the board works now.
2. Check if your external power supply fits the voltage requirements and if it provides enough
current. Try with different and more powerful power supply.
3. Check the USB hub you are using, plug the USB cable directly to the back of your personal
computer, check the USB cable.
4. The board might enter sleep mode very fast (especially if the Android was turned off without the
“Quick Boot” mode being ticked on). Try pressing or holding down the PWR_BUT for a couple of
seconds to wake it up.
Q: How do I write the Linux image to a micro SD card to use with my A20 board?
A: In order to prepare a Linux card under Windows use a free software for writing SD card images
like “Etcher” or “Win32DiskImager”.
Under Linux you can use “dd” to download the image to an SD card - for example, an image with
file name "debian_2g.img" would be downloaded to the SD card connected to a Linux machine
using one of the following commands:
# dd bs=4M oflag=sync if=debian_2g.img of=/dev/sdX
or
# cp debian_2g.img /dev/sdX
where X is the uSD card.
The tips above can also be used to prepare a microSD card with an Android image, suitable for a
microSD card.
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Q: How to detect and enable the Ethernet controller (if it is disabled by default)?
A: You can enable it by following these two steps:
1. Check under what name the LAN is listed with command "ifconfig –a"
2. If, for example, it is under eth0 name, then enable it with: "dhclient eth0"
This should enable the Ethernet and then SSH would also be available.
You can also enable auto detection of Ethernet on power-up by uncommenting #auto eth0 in
/etc/network/interfaces in the Linux image.
Q: How to generate boot-able SD-card Debian Linux image for A20-OLinuXino-MICRO?
A: Build instructions and required files for the latest Debian images can be found in our GitHub
repository. Here: https://github.com/OLIMEX/OLINUXINO/tree/master/SOFTWARE/A20
Q: How to edit board configurations and definitions in the official Debian Linux?
A: Do you want a custom video resolution output? Do you need a different port definition? Do you
need to change the hardware definitions of the board?
It is explained above in the manual. But you can also visit this wiki article: wiki article.
Q: How to edit board configurations and definitions in the official Android images?
A: There is a wiki article about that, please visit: wiki article.
Q: Is it possible to boot Debian from the extra flash memory? Do you provide such image?
A: Yes, it is possible. Use the latest Debian Jessie image and type "nandinstall" or “emmc”
(depending on whether you got a board with NAND or eMMC). More information about NAND
installation can be found in this wiki article: installing Debian Jessie to the 4GB NAND memory.
More information about eMMC installation can be found in this wiki article: installing Debian
Jessie to the eMMC memory.
There are other people who are also successful in booting Debian from the NAND. Make sure to
check on the forum. Make sure to check the number of very good and optimized A20-OLinuXino
Debian images by Igor Pečovnik. There are also his instructions for NAND installation of Debian:
link to his web-site.
Q: Can I use mainline kernel instead of Sunxi kernel?
A: You can. However, most non-sunxi kernels are headless – no audio or video output are
supported. If you don't need audio or video – go for it – it had been tested and confirmed working
(there are installation reports even) here: https://wiki.debian.org/InstallingDebianOn/Allwinner
Q: I have a version of the board with extra flash memory. The board doesn't seem to have
Android loaded.
A: We no longer load Android to the flash memory of the boards. You can upload Android
following the advice above in this document.
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Q: How to install Android on an SD-card?
A: First download one of the official Android images, which might be found in the Android section
above.
Make sure that the download link you visit clearly indicates that the image is suitable for the
microSD card since there are images suitable for NAND memory also. The images suitable for the
microSD memory and those suitable for NAND card are different. However, the upload method is
almost identical – using PhoenixSuit.
There are two types of Android images for microSD card that we usually provide and each of them
has to be downloaded to a microSD card using a different method. The image provided for microSD
card is either the native Android image that can be downloaded to the card via a software tool like
PhoenixSuit (through the board) or an image taken from an already prepared microSD card that
requires to simply write the image (through a microSD card reader).
It is more likely that you have an Android image that requires a simple copy to a card. If that is the
case you can follow the exact steps as for Linux (e.g. using "Win32 Disk Imager" or "dd"
command).
In order to prepare a microSD card with a native Android you will need a software tool called
PhoenixSuit and then:
• Install and run PhoenixSuit.
• Go to the firmware tab of the program and point to a valid Android image (note that the
images on Gdrive are compressed and you have to extract them to .img files to be able write
them with PhoenixSuit)
• Disconnect the power supply and USB cable from the A20 board. Put an SD card in micro SD
holder. We recommend 4GB class 10 card.
• Press and hold RECOVERY button, apply power supply (6-16)V, release RECOVERY button.
• Connect USB cable to the mini USB connector.
• You will be asked for drivers for the boot-loader. Navigate to the folder where you extracted
the PhoenixSuit and install the drivers from the respective executables (or manually point the
installer to the drivers folder in the PhoenixSuit installation path).
• PhoenixSuit will detect the board and would ask for the method of writing the image. Choose
method of writing the image and confirm your wish to write the image.
• Wait till upgrade succeeds
Note that it is not recommended to have your mini USB connected to an external USB hub. This
might cause delays and might distort the signal levels. Always test with the USB connected straight
to the USB ports of your computer.
Important: When Android runs for very first time it takes several minutes to initialize all files and
buffers please do not cut the power supply during this process! Also when fresh image is installed
fast boot may be disabled, which means that when you apply power supply after few seconds
Android will go in sleep mode and you have to press POWER button to start it, you can change to
fast boot when you power off there is dialog box asking you if you want next boot to be fast boot,
you have to check this box before you power off. Also note that you must do touch screen
calibration when you run Android for very first time which might require a mouse.
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8.5 Product support
For product support, hardware information and error reports mail to: support@olimex.com. All
document or hardware feedback is welcome. Note that we are primarily a hardware company and
our software support is limited. Please consider reading the paragraph below about the warranty of
Olimex products.
All goods are checked before they are sent out. In the unlikely event that goods are faulty,
they must be returned, to OLIMEX at the address listed on your order invoice.
OLIMEX will not accept goods that have clearly been used more than the amount needed to
evaluate their functionality.
If the goods are found to be in working condition, and the lack of functionality is a result of
lack of knowledge on the customers part, no refund will be made, but the goods will be returned
to the user at their expense.
All returns must be authorized by an RMA Number. Email support@olimex.com for authorization
number before shipping back any merchandise. Please include your name, phone number and order
number in your email request.
Returns for any unaffected development board, programmer, tools, and cables permitted within 7
days from the date of receipt of merchandise. After such time, all sales are considered final.
Returns of incorrect ordered items are allowed subject to a 10% restocking fee. What is
unaffected? If you hooked it to power, you affected it. To be clear, this includes items that
have been soldered to, or have had their firmware changed. Because of the nature of the
products we deal with (prototyping electronic tools) we cannot allow returns of items that have
been programmed, powered up, or otherwise changed post shipment from our warehouse.
All returned merchandise must be in its original mint and clean condition. Returns on damaged,
scratched, programmed, burnt, or otherwise 'played with' merchandise will not be accepted.
All returns must include all the factory accessories which come with the item. This includes
any In-Circuit-Serial-Programming cables, anti-static packing, boxes, etc.
With your return, enclose your PO#. Also include a brief letter of explanation of why the
merchandise is being returned and state your request for either a refund or an exchange.
Include the authorization number on this letter, and on the outside of the shipping box.
Please note: It is your responsibility to ensure that returned goods reach us. Please use a
reliable form of shipping. If we do not receive your package we will not be held liable.
Shipping and handling charges are not refundable. We are not responsible for any shipping
charges of merchandise being returned to us or returning working items to you.
The full text might be found at https://www.olimex.com/wiki/GTC#Warranty for future reference.
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