The SinA31s is an A31s core/daughter board combo from Sinlinx. The core board can be purchased separately and integrated into other projects.

Identification

Sinlinx SinA31s
Manufacturer	Sinlinx
Dimensions	170mm x 118mm
Release Date	August 2014
Website	Device Product Page
Specifications
SoC	A31s @ 1008Mhz
DRAM	1GiB DDR3 @ 432MHz (2x Samsung K4B4G1646Q-HYK0)
NAND	4 / 16 GB eMMC (Samsung KLMAG2GE4A-A001)
Power	DC 5V @ 2A, Battery connector solder points
Features
LCD	1024x600 (7" optional)
Touchscreen	X-finger capacitive (AWinic AW5206) on optional LCD
Video	HDMI (Type A - full), optional LCD-VGA converter
Audio	3.5mm headphone plug, 3.5mm microphone plug, HDMI, SPDIF
Network	10/100Mbps Ethernet (Realtek RTL8201CP)
Storage	µSD, eMMC
USB	5 USB2.0 Host, 1 USB2.0 OTG
Other	IR
Headers	LCD, SDIO, CSI, USER IO

The PCB has the following silkscreened on it:

SINA31S 芯灵思 | SINLINX

In android, under Settings->About Tablet, you will find:

Model Number: Allwinner-Tablet
Build Number: fiber_a31st-eng 4.2.2 JDQ39 20140725 test-keys

Sunxi support

Current status

This board is supported on mainline U-Boot and Linux kernel. See sections below.

Manual build

You can build things for yourself by following our Manual build howto and by choosing from the configurations available below.

U-Boot

Mainline U-Boot

For building mainline u-boot, use the SinA31s target.

Mainline kernel

Use the sun6i-a31s-sina31s.dtb device-tree file for the mainline kernel.

Tips, Tricks, Caveats

FEL mode

The U-Boot button triggers booting from mmc0 directly, and falls back to FEL mode if that fails.

Core / Daughter Board

The SinA31s consists of a core board and a daughter board, or as the vendor calls them, a CPU board and an SDK board.

Core Board

The core board consists of the A31s SoC, AXP221s PMIC, DRAM, eMMC, and supporting components. There are at least 2 revisions, though there doesn't seem to be any significant changes.

There are 3 also empty pad groups, J1, J2, and J3. J1 has UART0 and JTAG pins. J2 has I2S0 pins. J3 has CPUS UART and JTAG pins.

SDK Daughter Board

The daughter board breaks out all the pads from the core board into useful peripherals. There are at least 2 revisions. One way to see if you have a newer board is to check whether the HDMI port has ESD protection components near it.

The SDK daughter board has many connectors, as can be seen from the pictures below. There are 4 expansion headers: LCD, Camera, SDIO, and USER IO. The first three are designed to work with modules from Sinlinx, though you may use other modules provided you swap around the cabling.

The USER IO header is different between older and newer revisions.

Optional LCD / VGA converter

Sinlinx provides a 7" LCD with capacitive touchscreen, or an LCD to VGA converter board, for video display.

7" LCD screen

To use the LCD with mainline U-boot, have the following config options set:

CONFIG_VIDEO_LCD_MODE="x:1024,y:600,depth:18,pclk_khz:66000,le:90,ri:160,up:3,lo:127,hs:70,vs:20,sync:3,vmode:0"
CONFIG_VIDEO_LCD_DCLK_PHASE=0

Serial console port

The SDK daughter board uses a converter chip to convert the UART signal level to RS232 levels. On the upper side of the board is a 9-pin RS232 connector.

You can also use the UART0 pads on the core board.