A31-SOM update


About year ago we posted on this blog about our work on A31 SOM module, a lot of time passed away so we would like to make clear statement about it’s status.

A31 SOM hardware was complete long time ago, but we found lot of bugs in A31 during the software development. Lot of things do not work as expected and the chip have overall poor performance. The video is with PowerVR which means there will be no Linux acceleration forever. All you will got running on it with hardware acceleration is Kernel 3.4 with Android. Memory do not work reliable above 200Mhz clock which is terrible performance. While we have hesitated if we have to put more effort on this chip we got notice from Allwinner that they discontinue A31 and A31s production which ended our hesitation.

A31 has very short life, Tom Cubie shared on IRC before while that Allwinner internally hate this chip with all it’s bugs too 🙂 so I guess Allwinner also got relieve to get rid of it.

Leasons learned, we move forward 🙂

Our first A31-SOM – Quad Core ARM Cortex-A7 System on Module prototypes work fine!


We just assembled our first A31-SOM module prototypes.


They have these features:

  • A31 Quad Core Cortex-A7 @ 1Ghz, Octa core Power VR SGX544MP2 GPU, designed for power efficiency, 1MB L2 Cache, 32K I-Cache, 32K D-Cache, FPU, NEON SIMD
  • 2GB DDR3 RAM with 64 bit data bus for fast access
  • optional 8GB NAND Flash
  • Power Management Unit AXP221
  • LiPo battery charger and step up for USB 5V supply
  • micro SD card
  • 3 buttons
  • UART0 console connector
  • all GPIOs and pins on x6 40 pin 0.05″ connectors
  • RTC, Timer, HS-Timer
  • 16-Ch DMA
  • x2 USB Low/Full/High speed Hosts
  • 4SPI, 5 TWI/I2C
  • x6 UARTS
  • x2 PCM
  • x2 I2S
  • ITU601 / MIPI CSI
  • HDMI 1.4
  • x2-CH LVDS
  • x2-CH RGB LCD
  • IR
  • GMAC
  • Audio codec
  • 4K x 2K video playback

We need some weeks to test them before run production, so these modules will be in stock end of September earliest. A31-SOM price will start from EUR 44 for 1000 pcs, A31-SOM-8GB price will start from EUR 54 for 1000 pcs order.

We also designed A31-SOM-EVB for A31-SOM modules, which is OSHW mother board reference design and have these features:

  • Gigabit Ethernet
  • USB-OTG connector
  • 2x USB Host connectors
  • UEXT1 and UEXT2 connectors
  • SD-MMC connector
  • LCD connector compatible with our LCD displays – 4.3″, 7″, 10″, 15.6″, 15.6″HD
  • Audio output 3.5 mm jack
  • Audio input 3.5mm jack
  • 2Mpix @30 fps Camera on board
  • HDMI connector
  • LiPo battery connector
  • RTC CR2032 Li battery backup connector
  • GPIOs on prototype friendly 0.1″ connectors
  • Power jack 6-16VDC

A31-SOM-EVB evaluation board with A31-SOM-8GB on it will cost EUR 97 in single quantity.

Although A31 is only Cortex-A7 you can see here  interesting comparison between RK3188 and A31 video performance.

A31 have better picture and faster video playback than RK3188 which do not have native HDMI but used LCD-> HDMI converter.

A31 supports up to 4K video playback and have 64 bit RAM data bus.

Android 4.2.2 runs fine on A31-SOM and all features are supported.

Regarding the Linux Support, there is more than year and half efforts from Maxime Ripard @ Free Electrons to bring A31 to mainline, but still some major drivers are missing though like Video, Audio and NAND.

Linux-Sunxi tree miss A31 so far, probably because there is no good development hardware for A31 platform – all devices available are either tablets either Android dongles with no Ethernet, GPIOs etc. exposed. Now when this changes perhaps some Linux-Sunxi developers may be interested 😉 we built 5 prototypes and use only 2 of them so we have 3 to send to interested developers.

With the current Linux support A31 is still good for headless Linux server with the Quad cores, 2GB RAM and Gigabit Ethernet.

Linux kernel from Allwinner SDK is also option but it will be step back from mainline. Anyway with the missing Linux-Sunxi support this is also an option for these who need Linux instead of Android.

A31-SOM will be good platform for digital signage, video processing, IP cameras, or VoIP etc.


Mozilla Launches Contribution Program to Help Deliver Firefox OS to A31 Tablets


I just received this message from Eva Wu – the Marketing Manager at Allwinner:


The first Firefox OS smartphones launched just a few months ago and we are already making progress on building Firefox OS for more platforms and devices.

One of those projects is progressing quickly and we need help from contributors to complete the code. To make this easier, we are launching a new contribution program aimed at accelerating the build of Firefox OS for tablets and its supporting ecosystem. To do this, we will provide dedicated contributors with access to resources and reference tablet hardware. We have to make the hardware available before the software is final to make it possible for contributors around the world to help us complete the build of Firefox OS for tablets.

We are working closely with partners like Foxconn and developers on the tablet development of Firefox OS. Because Firefox OS is built on the Web, and the Web is a truly extensible platform, we can continue to optimize Firefox OS for smartphones, while also building for tablets and different uses around the world with the help of our community.

Once we have completed work on Firefox OS for tablets with the help of this contribution program, we’ll get ready to share it with the world.

*Initial Partners and Hardware:*

Specs are:

InFocus 10″(Allwinnner A31)
1280×800 24bit color
16GB Storage
802.11 b/g/n
267x171x9.7mm 580g

We will be working with partners like Foxconn to expand this program for more 
developers and contributors soon.

*How the program will work:*

  * The program will start in the coming weeks, when we will share more details about how contributors can apply to receive a reference tablet.
  * We will work together to complete the tablet version of Firefox OS.
  * We will provide guidance on where we need contributions to complete the tablet version of Firefox OS.
  * Nightly builds will be offered for developers to keep up to date.
  * All program details will be posted here on Hacks in the coming weeks

*Who the program is aimed at:*

  * Developers interested in or with previous knowledge of developing for the core Firefox OS (focus on Gecko/GFX, Gaia, UX, Productivity and Systems Apps).
  * Firefox OS localizers – to help localize and translate the tablet version of Firefox OS for global markets.
  * Testers and bug fixers – we will be calling for participation from both people who can test the latest tablet builds and file bugs and also developers who can file and fix bugs.

Stay tuned for more updates in the next few weeks on how to get involved in the program.


Looks interesting for people who want to have more access to Allwinner Linux development as probably this will give them access to more Allwinner internals.

A31 Quad Core Cortex-A7 Android miniPC CS868 teardown


Few weeks ago I ordered A31 Android stick on ebay for $98 and I got it in the post today. The price is high compared to the other Android sticks, but the 2GB DDR3 memory and 8GB NAND Flash with the current crazy memory prices justify this. A31 price alone is quite modest as you can see even from our web shop and not so higher than A10-A20 https://www.olimex.com/Products/Components/IC/A31/

so you may bet the price of the memory in this miniPC is more than the four core processor itself

The product name is CS868 Android miniPC made with A31 quad core Cortex A7 processor from Allwinner.

The datasheet of A31, user manual and reference schematics are in our GitHub https://github.com/OLIMEX/OLINUXINO/tree/master/HARDWARE/A31-PDFs

As we evaluate the possibility for OLinuXino with four core processor I ordered this one miniPC at least to may experiment with the software support.

Needless to say the first thing I did was to open it and look inside.


if you do wonder what are these spots on the NAND flash and one of the DDR3 chip, this is traces from the glue which is used for this huge aluminum heatsink placed on top of A31

the power supply adapter is 5V 2A i.e. 10W and if these 4 cores take x 1.2-1.3W as A1x the radiator is must for this BGA package.

and look at the back:


as you can see on the picture A31 comes with 2GB of RAM and 8GB of NAND flash, as the databus is 64 bit wide it reads and writes the memory content twice faster than A10-A20 where the bus is 32 bit and four times faster than A13-A10S where the databus is only 16 bit wide.

What I do not like in these Android sticks is the use of micro USB connectors, this is so unreliable connector that I do not understand why manufacturers still use it specially for power supply where frequently plug unplug operations are necessary. mini USB is thousands times more reliable than micro USB connector.

Basically beside the AXP221 PMU, DDR memory and NAND memory and WIFI module there is nothing else inside. This is shame as this chip have over 300 GPIOs and interfaces which stay unused.

Gigabit Ethernet, UARTs, SPIs, I2Cs, CSI, LCD, LVDS, to name few.

Complete range of Allwinner SoC now are in our online shop



In our IC section now you can buy all of Allwinner SoC in single quantity: A10, A10S, A13, A20 and A31, together with Power Managment ICs necessary for their operation: AXP152 for A10S, AXP209 for A10, A13, A20 and the monster AXP221 with 21 programmable voltages for A31.

DCDC step up and down converters, USB power management and current limiters, DDR3 and NAND flash, everything you need to build your Linux prototype is available.

Allwinner A31 Quad Core Cortex-A7 processors now are in production


A31 is the first Allwinner’s 4 core processor.

Compared to A20 is should have double the productivity as have 64 bit RAM data bus and 4 cores vs 2 cores in A20.

How this compare to A10/A10S/A13 we still don’t know, but recent tests show that A20 perform 3 times faster than A10 although on paper it should be only 1.9 times faster.

A31 have PowerVR GPU with 8 cores, which will make it powerful for games and extensive graphics. One potential problem for using it with Linux is that Open Source community Lima project (http://limadriver.org) is mostly focused on reverse engineering MALI and they actually released open source drivers which performs faster and better than ARM own drivers which according to Luc Verhaegen’s blog (http://libv.livejournal.com) makes ARM managers quite unhappy as they have to sell something closed sourced which performs worse than the open source alternative 🙂

With the success on MALI/LIMADRIVER we are confident that Open Source community will have soon or later reverse engineering driver for PowerVR too, A31 is just too powerful and low cost to ignore!

A31 can address up to 2GB or DDR3 memory, Video output support up to 4096 x 4096 pixels, the camera video inputs are 4 and support 1Gbps stream i.e. 12Mpixel cameras can stream with up to 60fps.

A31 brief features are:

  • Cortex-A7 4 core processor
  • PowerVR GPU with 8 cores
  • up to 2GB DDR3 RAM support
  • two Audio DACs with 100dBA SNR and 192kHz sampling
  • 8/16bit NAND databus
  • GPADC with 12bit resolution 1MSPS
  • 4 independant SD/MMC controllers with up to 100Mhz clock, up to 128GB cards
  • USB-OTG 2.0
  • LRADC 6-bit for buttons interface
  • two I2S/PCM 192kHz sampling and MCLK for external CODECs
  • 4 PWMs with prescallers
  • SPI/SSI interface with up to 150Mbps clock
  • Gigabit Ethernet GMII/MII interface
  • CIR – IR controller
  • 6 UARTs
  • 4 SPIs
  • 5 I2C
  • P2WI push-pull I2C

few days ago Allwinner sent us 1 tray of 84 pcs A31 + 84 pcs AXP221:


… so after we complete A20-SOM we may decide to continue with A31-SOM unless something more interesting pop up.

A31 is real monster with 609 balls on 0.65mm step it may be not possible to route it on 4 layers.

Specially for A31 Allwinner designed AXP221 power managment device. AXP221 is also monster chip with 5 programmable DCDC convertors with 20mV step and 14 programmable LDOs with 100mV step, integrated MOSFET switches and LiPo Flash charging. We have never seen equivalent of this chip at other vendors.

What we will probably go for is A31-SOM with 2GB RAM and power managment on board + A31-EVB evaluation board which utilize A31-SOM.

The price of A31 is double than A20 and with the double amount of RAM we guess A31-SOM will cost about double what A20-SOM will cost.

As A31 uses 64 bit DDR memory bus it may be possible to design module which accept normal computer DIMM RAM modules, this is option which we will investigate further.

The A31 datasheet and some reference PDF schematics received from Allwinner are put on GitHub.