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Identification

Tena b133
Manufacturer	Shenzhen Tena
Dimensions	widthmm x breadthmm x heightmm
Release Date	September 2013
Website	Product page
Specifications
SoC	A20 @ 1Ghz
DRAM	1GiB DDR3 @ 432MHz
NAND	4GB
Power	DC 5V @ 2A
Features
Video	HDMI, VGA
Audio	3.5mm AV connector, HDMI
Network	WiFi 802.11 b/g/n (Realtek RTL8188ETV), 10/100Mbps Ethernet (IC Plus IP101A)
Storage	µSD
USB	2 USB2.0 Host
Headers	UART

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

Model Number: B133
Build Number: A20_B133-eng 4.4.4 JDQ39 20140221 test-keys

Sunxi support

Current status

Patches are on the mailing list, but there are some issues with the sunxi-3.4 stable kernel and the way the USBCs are configured in the .fex. The sunxi-3.3 kernel does seem to work. Following works with sunxi-3.3 :

Wireless
NAND
USB Ports
SDCards
10/100MBps Ethernet

What does not work:

G2D engine seems to have problem with the sunxi-3.3 kernel

Images

HW-Pack

BSP

Manual build

For building u-boot, use the "MANUFACTURER_DEVICE" target.
The .fex file can be found in sunxi-boards as MANUFACTURER_DEVICE.fex

Everything else is the same as the manual build howto.

Tips, Tricks, Caveats

FEL mode

There is a pinhole on the case to reach the recovery button which is near the RJ45 port. The USB port nearest to the SDcard is of OTG type even though it looks just like a normal USB port . If the device is put in recovery mode and then the port can be used to connect the device to a PC using a usb cable that is female type on both the ends. It was also possible to flash this device with LiveSuit on linux using the USB port.

USB power

When trying to power over USB, do not use a host port from another device, but instead use standalone powersupply still as otherwise the amperage delivered does not suffice.

This is a case where you will run into trouble with your UART adapter if you have connected Vcc.
Update: It is possible to power up and run the device using the OTG USB port on the device. Refer Fel section for identification of the OTG port. However the current from usb hosts are limited to 500mA.

Power On/Off

There is no power switch, you have to power it down through software and restart it by reattaching the power cable.

Adding a serial port (voids warranty)

DEVICE UART pads

Note if you are using CA-42 cable u need to attach the VCC.

libv> i do not believe that, this link shows the cable as a generic UART, without Vcc attach.

Device disassembly

Disassembly is easy. Just unscrew the 4 screws concealed below the rubber footpads. Then lift up the TOP cover with a paper cutter. It should pop out with ease. The PCB can be taken out gently from the casing by lifting it up from the end which does NOT carries the connectors. Take care of the wireless antenna that is glued on the edge of the casing. Do NOT desolder the atenna lead unless you really need to. (PS: do not attempt to force out the PCB with sdcard plugged in unless you want to Guillotone your card ).

Locating the UART

There are four pin holes on the board on the left of the 2 memory chips. These holes first needs to be desoldered and then you can solder a 4 pin header block. the pin nearest to the memory banks is the GND to its left are the RX , TX and VCC.