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.