A20-OLinuXino-MICRO

A20-OLinuXino-MICRO features:

A20 Cortex-A7 dual-core ARM Cortex-A7 CPU and dual-core Mali 400 GPU
1GB DDR3 RAM memory
Optional 4GB NAND FLASH memory
SATA connector with 5V SATA power jack
HDMI FullHD 1080p
2x USB Low-Full-High-Speed hosts with power control and current limiter
USB-OTG with power control and current limiter
VGA output on 6-pin 1.25mm (0.05") step connector
100MBit native Ethernet
LiPo Battery connector with battery-charging capabilities
Audio headphones output
Microphone input on connector
2x UEXT connectors
LCD connector compatible with with 4.3", 7.0", 10.1" LCD modules from Olimex
160 GPIOs on three GPIO connectors
MicroSD card connector
SD/MMC card connector
DEBUG-UART connector for console debug with USB-SERIAL-CABLE-F
status LED
Battery charge status LED
Power LED
2KB EEPROM for MAC address storage and more
10 BUTTONS with ANDROID functionality + RESET button
4 mount holes
6-16V input power supply, noise immune design
PCB dimensions: 142 x 82 mm

Official Images Recommended by Olimex

Below you would find links to the official Debian and Android images. The images in this chapter were compiled by Olimex. They are recommended for beginners and first time users since they include full hardware support. If you are experienced Linux professional you might find bare-bone images and much more in the next chapter "Notable unofficial images".

Note that only the microSD connector is suitable for booting the desired operating system, the SD-MMC connector is not suitable for booting since it is not a part of the boot sequence (refer to A20 datasheet).

The downloaded file xxxx.7z is an archive of xxx.img file. In order to write the image on SD card you have to unzip the xxx.7z file.

For Windows: use 7zip and then use Win32DiskImager.exe (http://sourceforge.net/projects/win32diskimager/) to write the image

For Linux: use p7zip package. If you don't have 7zip installed first install it

   #apt-get install p7zip

Copy a20_debian_second_release.7z file in your directory and unzip the archive with

   #7za e a20_debian_second_release.7z

where a20_debian_second_release.7z The output should be a new 4GB file with extension img Put 4GB SD card in your card reader and type

   # ls /dev/sd

Then press two times <TAB> you will see a list of your sd devices like sda sdb sdc note that some of these devices may be your hard disk so make sure you know which one is your sd card before you proceed as you can damage your HDD if you choose the wrong sd-device. You can do this by unplugging your sd card reader and identify which "sd" devices remove from the list. Once you know which device is your sdcard like sda use this text instead of the sdX name in the references below:

   #dd if=a20_debian_second_release.img of=/dev/sdX

The Debian image is 4GB and the file system can be extended to suit a bigger card. Use the following three commands to execute a script that would use all the space of your card:

  sudo su
  resize_sd.sh /dev/mmcblk0 2
  reboot

Linux

These official Debian images are suitable for a microSD card. Information on booting Debian from the NAND might be found in this wiki article: how to install Debian to NAND. Download methods and locations for the official images might be found below:

Latest official image - Debian 8 (Jessie) (recommended):

Torrent of official Debian Jessie release 12: A20-OLinuXino-MICRO Debian Jessie with kernel 3.4.103+ release 12

Image build instructions and required files for the latest Debian 8 Jessie image: build instructions and required files at the GitHub page

Stable official image - Debian 7 (Wheezy) (recommended):

Torrent of Debian release 10: A20-OLinuXino-MICRO Debian with kernel 3.4.90+ release 10

Image description and typical interfacing: description and basic usage of different peripherals at at the GitHub page

Image build instructions and required files for Debian Jessie release 12 might be found here: build instructions and required files at the GitHub page

Older official releases (not recommended):

Torrent of official Debian Jessie release 11: A20-OLinuXino-MICRO Debian Jessie with kernel 3.4.103+ release 11

Image build instructions and required files for the Debian 8 Jessie release 11 image: build instructions and required files at the GitHub page

Torrent of Debian release 8: A20-OLinuXino-MICRO Debian with kernel 3.4.90+ release 8

Direct download of Debian release 7: A20-OLinuXino-MICRO Debian with kernel 3.4.67+ release 7

The newest release has the following features:

Default Login: root/olimex
Linux Kernel 3.4.90+
LXDE desktop environment
Mplayer CLI
smplayer
Midori browser
GCC 4.6
GPIO support
i2c-tools
dpkg
git
perl
xorg
Python 2.7
OpenCV
Scratch
vlc
minicom
HDMI
Micro SD card
SD/MMC card
OTG USB
HIGH SPEED HOST1 USB
HIGH SPEED HOST2 USB
ETHERNET 100MBIT
SATA
Audio IN
Audio OUT
Kernel support for USB-ETHERNET-AX88772B
Kernel suppot for MOD-WIFI-RTL8188
Support for Olimex-made displays and touchscreens: A13-LCD43TS 4.3″ LCD with backlight and touchscreen 480×272 pixels; A13-LCD7TS 7″ LCD with backlight and touchscreen 800×480 pixels; A10-LCD10TS 10.1″ LCD with backlight and touchscreen 1024×600 pixels;

Tested board peripherals with this image:

GPIO - located at /sys/class/gpio
LCD - supported LCD displays and touchscreens are the Olimex-made ones A13-LCD4.3TS, A13-LCD7TS, A13-LCD10TS
Touch screen - you need calibrate LCD before using touch screen. Type: ts_calibrate and then test it with ts_test
SATA - works including power on/off control
HDMI - the default HDMI resolution is 720p60(1280x720-60 Hz)
ASIX 8877 USB-LAN - USB-ETHERNET-AX88772B
WEB camera A4TECH
TL-WN721(TP-LINK USB wireless)
RTL8188CU - MOD-WIFI-RTL8188 - instructions on configuration might be found here How_to_configure_MOD-RTL8188_on_official_OLinuXino_Debian_releases
USB_OTG - works as OTG device and Low/Full/High USB host
USB_HOST_up - works as Low/Full/High USB host
USB_HOST_down - works as Low/Full/High USB host
mico_SD_card - allow Linux boot
secondary SD-MMC card - with card present detector
ETHERNET - 100Mb
Headphone OUT - audio output
MIC IN - microphone input
I2C2(100KHz) - /dev/i2c-2
I2C1(100KHz) - /dev/i2c-1
UART6 - /dev/ttyS1
UART7 - /dev/ttyS2

Note: the A20-Debian-SD card which we have in our web store contains the same image on 4GB Class10 fast micro SDcard, if you want to use this image please use card of Class10 speed or the performance of Linux will be very slow.

Note: in the previous Debian releases the Ethernet was auto-detected and initialized during boot BUT this was causing big delays in the start-up of the board if you didn't want to use Ethernet or if there wasn't Ethernet cable connected.

You can enable it by following these two steps:

1. To check under what name the LAN is associated write "ifconfig –a"

2. If, for example, it is under eth0 name, then write: "dhclient eth0"

This should enable the Ethernet and then SSH would also be available.

Android

Torrents of official Android releases are below. Please read description of the image carefully.

Torrent of Android release 3 for NAND memory with HDMI and 7 inch LCD (800x480) support: A20-OLinuXino Android for NAND with HDMI and 800x480 video support

Torrent of Android release 3 for NAND memory with HDMI and 10 inch LCD (1024x600) support: A20-OLinuXino Android for NAND with HDMI and 1024x600 video support

Torrent of Android release 1 for microSD card with HDMI and 7 inch LCD (800x480) support: A20-OLinuXino Android for microSD card with HDMI and 800x480 video support

Torrent of Android release 1 for microSD card with HDMI and 10 inch LCD (1024x600) support: A20-OLinuXino Android for microSD card with HDMI and 1024x600 video support

Direct download of Android 4.2.2 NAND image made with A20-SDK2.0 for A13-LCD7"TS and A13-LCD10"TS

Direct download of Android 4.2.2 SD-card image made with A20-SDK2.0 for A13-LCD7"TS and A13-LCD10"TS

The Android image has the following features:

Android 4.2.2
NAND image i.e. will work only on A20-OLinuXino-MICRO-4GB
Supports 7" LCD 800x480 pixels and 10" LCD 1024x600 pixels
HDMI support (720p default)
both LCD and HDMI work together
Touchscreen supported
GPIO support
Native Ethernet 100Mbit
USB-Ethernet ASIX 88772
USB-WIFI RTL8188
USB-OTG support USB device and USB host with Low/Full/High speed
USB-HOST-top Low/Full/High speed
USB-HOST-bottom Low/Full/High speed
micro SD card
Audio OUT
Audio In
I2C1
I2C2
UART6
UART7
Buttons

What is left unsupported in Android:

SATA
SD-MMC card on bottom

Notable unofficial images

Below you would find locations to images released by the community. These are not officially supported by Olimex, however, some of these releases are pretty good and worth a try:

A number of very good and optimized A20-OLinuXino-MICRO with Debian and Ubuntu images by Igor Pečovnik. There are also scripts and instructions for NAND installation of Linux. Note that these are headless images - no video output out-of-the-box: link to his web-site

Documents

Hardware

Power supply and consumption

A20-OLinuXino can be powered from three sources:

+6-16VDC voltage applied PWR jack
+3.7V from LiPo re-chargable battery connected to LiPo board connector
+5V applied to USB-OTG connector

Power consumption is as follows:

LiPo 3.7V power battery: 0.17-0.25A depend on processor load
+6VDC input power: 0.18-0.33A depend on processor load
+16VDC input power: 0.11-0.17A depend on processor load

Comparison table of power consumption might be found at the following link.

LiPo battery allow backup power supply when main power is interrupted. A20-OLinuXino have power managment IC which charge the battery when main power is present, when power is interrupted the LiPo battery automatically provide backup power supply. Step-up converter prvide 5V for the USB peripherials too. For LiPo batteries we recommend these:

Board dimensions

A20-OLinuXino-MICRO and A20-OLinuXino-MICRO-4GB basic dimensions in mils: image in PNG format

CAD files

A20-OLinuXino is Open Source Hardware, CAD files are available at GitHub

The CAD product used to design OLinuXino is Eagle and you can download evaluation free version from their web.

Board Layout

Be careful with TV monitors without grounding

Here you can read how easy you can damage your OLinuXino if you connect it to TV without grounding.

Software

Linux Commands

Linux-Commands Brief Linux Command reference

Python

pyA20 is Python library for access to A20-OLinuXino-MICRO GPIOs, I2C, SPI

Use:

   #!/usr/bin/env python
   
   import A20_GPIO as GPIO
   
   #init module
   GPIO.init()
   
   #configure module
   GPIO.setcfg(GPIO.PIN#, GPIO.OUTPUT)
   GPIO.setcfg(GPIO.PIN#, GPIO.INPUT)
   
   #read the current GPIO configuration
   config = GPIO.getcfg(GPIO.PIN#)
   
   #set GPIO high
   GPIO.output(GPIO.PIN#, GPIO.HIGH)
   
   #set GPIO low
   GPIO.output(GPIO.PIN#, GPIO.LOW)
   
   #read input
   state = GPIO.input(GPIO.PIN#)
   
   #cleanup
   GPIO.cleanup()

GPIO under Linux

A very good GPIO guide by Dr. Guido Pelz might be found here: http://www.py6zgp.com/download/A20-GPIO.pdf

You can read data from a given GPIO port. The logical ranges are usually as follows: 0V-1V for LOW (or 0) and 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!

In order to use A20 GPIO's first you have to export them. You can export a single GPIO:

   root@A20:~# echo gpioXX > /sys/class/gpio/export

To export a range of GPIOs (from 1-230 in the example below) use:

   root@A20:~#  for i in `seq 1 1 230`; do echo $i > /sys/class/gpio/export; done

list of all available GPIO

   root@A20:~# ls /sys/class/gpio/
   export       gpio21_pc3/  gpio33_pb8/  gpio45_ph27/ gpio57_ph17/ gpio69_pg5/
   gpio10_pe9/  gpio22_pc7/  gpio34_pb10/ gpio46_ph0/  gpio58_ph18/ gpio6_pe5/
   gpio11_pe10/ gpio23_pc16/ gpio35_pb11/ gpio47_ph2/  gpio59_ph19/ gpio70_pg6/
   gpio12_pe11/ gpio24_pc17/ gpio36_pb12/ gpio48_ph7/  gpio5_pe4/   gpio71_pg7/
   gpio13_pi14/ gpio25_pc18/ gpio37_pb13/ gpio49_ph9/  gpio60_ph20/ gpio72_pg8/
   gpio14_pi15/ gpio26_pc23/ gpio38_pb14/ gpio4_pe3/   gpio61_ph21/ gpio73_pg9/
   gpio15_pi0/  gpio27_pc24/ gpio39_pb15/ gpio50_ph10/ gpio62_ph22/ gpio74_pg10/
   gpio16_pi1/  gpio28_pb3/  gpio3_pe2/   gpio51_ph11/ gpio63_ph23/ gpio75_pg11/
   gpio17_pi2/  gpio29_pb4/  gpio40_pb16/ gpio52_ph12/ gpio64_pg0/  gpio7_pe6/
   gpio18_pi3/  gpio2_pe1/   gpio41_pb17/ gpio53_ph13/ gpio65_pg1/  gpio8_pe7/
   gpio19_pi10/ gpio30_pb5/  gpio42_ph24/ gpio54_ph14/ gpio66_pg2/  gpio9_pe8/
   gpio1_pe0/   gpio31_pb6/  gpio43_ph25/ gpio55_ph15/ gpio67_pg3/  gpiochip1/
   gpio20_pi11/ gpio32_pb7/  gpio44_ph26/ gpio56_ph16/ gpio68_pg4/  unexport

Example on how to write to a GPIO. For instance - toggle onboard LED. The LED is connected to PH2.

1. Export gpio47_ph2

   root@A20:~# echo gpio47 > /sys/class/gpio/export

2. Set PH2 as output

   root@A20:/sys/class/gpio/gpio47_ph2# echo out > direction

3. Set high position (1) of PH2 - LED is ON

   root@A20:/sys/class/gpio/gpio47_ph2# echo 1 > value

4. Set low position (0) of PH2 - LED is OFF

   root@A20:/sys/class/gpio/gpio47_ph2# echo 0 > value

Example on how to read GPIO (with GPIO #49):

1. Export GPIO 49

   echo 49 > /sys/class/gpio/export

2. Set input

   echo "in" > /sys/class/gpio/gpio49_ph9/direction

3. Read value GPIO 49

   cat /sys/class/gpio/gpio49_ph9/value

4. Unexport GPIO 49 when finished

   echo 49 > /sys/class/gpio/unexport

Add Voice to your OLinuXino project

Installation of Festival on OLinuXino

How To?

How to correctly power off OLinuXino running from NAND Flash

In this Blog post we explain what are the problems. This is common problem for all computers running OS. Here you can read more about MLC NAND Flash and Linux file system.

Is it possible to boot Debian from NAND? Do you provide such image?

Yes, it is possible. Use the latest Debian Jessie image and write "nandinstall". More information can be found in this wiki article: installing Debian Jessie to the 4GB NAND 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

How to generate boot-able SD-card Debian Linux image for A20-OLinuXino?

Build instructions and required files for the latest Debian images: instructions and files at the GitHub page

Official Olimex wordpress article on how to extend the previous build of Debian Linux 3.4 with hardware acceleration support, keep a look at the wordpress for more interesting articles

Sunxi u-boot loader The linux-sunxi git page contains a lot of sources for all Olimex Allwinner boards.

How to download new Android image to the NAND memory of my A20 board?

To repair the image on the NAND re-upload it following these steps:

1. Install and run PhoenixSuit (can be found here: download from google drive).

2. Go to firmware tab of the program and point to a valid Android image (the latest official one may also be downloaded above).

3. Disconnect the power supply and USB cable from the A20 board.

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

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.

How do I write the official Android image to a micro SD card for my A20 board?

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 (can be found here: download from google drive)

• 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.

How do I write the Linux image to a micro SD card to use with my A20 board?

To write a Linux image to an SD card under Windows we use Win32 Disk Imager):

Download Win32 Disk Imager Win32 Disk Imager
Insert card
Start program
Select file
Click "write"

To write a Linux image to an SD card under Linux:

For instance you have an image with the file name of "debian_2g.img". It 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.

How to change HDMI, VGA and LCD resolutions in the official Debian image?

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

Type:

   ./change_display*

or

   ./change_display_A20_OLinuXino.sh

and press "Enter".

Then choose the resolution and the interface(LCD, HDMI or VGA). Note that the selection of a specific resolution is done by navigating with the arrow keys and pressing "space" button. Make sure the asterisk marks your selection properly.

The supported resolutions are:

For LCD:

1. 4.3" (480x272)
2. 7" (800x480)
3. 10" (1024x600)
4. 15.6" (1366x768)

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

For HDMI:

0. 480i
1. 576i
2. 480p
3. 576p
4. 720p50
5. 720p60
6. 1080i50
7. 1080i60
8. 1080p24
9. 1080p50
10. 1080p60

For VGA: (note that the VGA signals are routed to custom 6 pin connector and you need from adapter to standard VGA connector)

0. 1680x1050
1. 1440x900
2. 1360x768
3. 1280x1024
4. 1024x768
5. 800x600
6. 640x480
7. 1920x1080
8. 1280x720

How to generate Arch Linux image?

Recent forum post by user progmetalbg here: at Olimex forums

Older step by step instructions on how to build Arch Linux image

How to detect and enable the Ethernet controller (if it is disabled by default)?

Note: in the previous Debian releases the Ethernet was auto-detected and initialized during boot BUT this was causing big delays in the start-up of the board if you didn't want to use Ethernet or if there wasn't Ethernet cable connected.

You can enable it by following these two steps:

1. To check under what name the LAN is associated write "ifconfig –a"

2. If, for example, it is under eth0 name, then write: "dhclient eth0"

This should enable the Ethernet and then SSH would also be available.

How to install Android on SD-card?

Blog post about it

How to access UART, I2C, GPIOs under Android?

Use our Open Source OLinuXino A20-TOOLS

How to control PWM under Linux?

There is an article here: how to add pwm

How to build the Android 4.2.2 image for A20-OLinuXino-MICRO?

First you need to Download the A20 SDK2.0 Linux Kernel 3.4

Second you need to configure your environment read the instructions here

Then Build the kernel, kernel modules and u-boot

   cd lichee
   ./build.sh -psun7i_android

When done, continue with Bulding the android image:

   cd ../android4.2
   cd device/softwinner/
   tar zxfv olinuxino-a20.tgz
   cd ../../
   source build/envsetup.sh
   lunch #select olinuxino-a20_eng
   extract-bsp
   make -j4

Dave from Axon instruments wrote more detailed blog post about how he generates the Android image

I don't have neither serial cable, nor HDMI monitor. I also can't access the local Ethernet network. Can I somehow access the board anyway?

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.

How to edit board configurations and definitions in the official Debian Linux?

Do you want a custom video resolution output? Do you need a different port definition? Do you need to change the hardware defitions of the board?

You would need to edit the board's script.bin/script.fex file. How to do it is described in another separate article: How_to_edit_board_configurations_and_definitions_in_the_official_Debian_Linux.

How to properly calibrate a display under Debian

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

   #su olimex

enter the olimex password:olimex

   #sudo ts_calibrate

calibrate the touch screen and reboot the board

   #sudo reboot

It would be a good idea to test with Android or another Debian image also, it has a built-in calibration application by default.

How to add STK1160 video capture driver support in Kernel 3.4

STK1160 driver backport by Dimitar Tomov

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