Revision as of 06:01, 30 September 2013 by LubOlimex (talk | contribs) (How to change HDMI, VGA and LCD resolutions?)


A20-OLinuXino-MICRO features:

  • A20 Cortex-A7 dual-core ARM Cortex-A7 CPU and dual-core Mali 400 GPU
  • 1GB DDR3 RAM memory
  • 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 from OLIMEX

Note only microSD card will boot, SD-MMC card on the back will not boot as not part of boot sequence (reffer to A20 datasheet).


A20 Debian 4GB SD-card image release-4 with:

  • Linux Kernel 3.4.61+
  • XFCE4 desktop environment
  • Mplayer CLI
  • GCC 4.6
  • 4.3"(480x272), 7"(800x480) and 10" (1024x600) LCD and touchscreen support
  • GPIO
  • I2C
  • USB WIFI RTL8188CU, Ethernet AX88772B
  • Audio (MIC and Headphones)
  • dpkg
  • git
  • i2c-tools
  • perl
  • xorg
  • Python 2.7
  • OpenCV
  • Scratch
  • vlc
  • MOD-WIFI-RTL8188
  • A13-LCD 4.3″TS 4.3″ LCD with backlight and touchscreen 480×272 pixels
  • A13-LCD7″TS 7″ LCD with backlight and touchscreen 800×480 pixels
  • A10-LCD10″TS 10.1″ LCD with backlight and touchscreen 1024×600 pixels
  • HDMI
  • Micro SD card
  • SD/MMC card
  • SATA
  • Audio IN
  • Audio OUT
  • I2C2(400KHz)
  • I2C1(200KHz)
  • Default Login: root/olimex

Tested board peripherials with this image:

  • GPIO - located at /sys/class/gpio
  • LCD - supported are 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)
  • WEB camera A4TECH
  • TL-WN721(TP-LINK USB wireless)
  • RTL8188CU - MOD-WIFI-RTL8188
  • 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 4.2.2 image made with A20-SDK2.0 for A13-LCD7"TS and A13-LCD10"TS

The image is with these 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 left unsupported:

  • SATA
  • SD-MMC card on bottom


A20-SDK 2.0 for building Android images


A20-OLinuXino Board User Manual

A20-OLinuXino USer Manual

A20 Brief

A20-Brief description

A20 Datasheet

A20 datasheet

A20 User Manual

A20 Users manual


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

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





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


   #!/usr/bin/env python
   import A20_GPIO as GPIO
   #init module
   #configure module
   #read the current GPIO configuration
   config = GPIO.getcfg(GPIO.PIN#)
   #set GPIO high
   #set GPIO low
   #read input
   state = GPIO.input(GPIO.PIN#)

GPIO under Linux

In order to use A20 GPIO's first you have to export them. For example:

   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 how to toggle onboard LED. The LED is connected to PH2.

   root@A20:~# cd /sys/class/gpio/gpio47_ph2

make PH2 output

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

write 1 to PH2 - LED is ON

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

write 0 to PH2 - LED is OFF

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

How To?

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

Follow our blog post with step by step instructions Note that Linux-Sunxi Kernel is a work-in-progress, this means you can try the current stage/sunxi-3.4 branch but if something is broken and doesn't work just revert to the git tags we give in the blog and they should work for sure

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:

  • 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 Linux image to an 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


  • # cp debian_2g.img /dev/sdX

where X is the uSD card.

How to change HDMI, VGA and LCD resolutions?

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


   # ./change_display.sh

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

The supported resolution are:

For LCD:

  • 1. 4.3" (480x272)
  • 2. 7" (800x480)
  • 3. 10" (1024x600)

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.


  • 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 standart 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?

Step by step instructions 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.