Hyundai A7HD

= Identification =

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


 * Model Number: A7 HD
 * Build Number: RKS7S01_A7HD_20120412

= Sunxi support =

Current status
Supported. Touchscreen unknown.

Manual build specifics

 * For building u-boot, use the "hyundai_a7hd" target.
 * The .fex file can be found in sunxi-boards under as hyundai_a7hd.fex

Everything else is the same as the Manual build howto.

= Tips, Tricks, Caveats =

FEL mode
There are 4 buttons on the A7HD, the left one is the powerbutton, and any of the three other buttons can be used to trigger FEL mode, as described in the FEL mode howto.

Flaky WiFi
The A7HD has a known issue with less than ideal WiFi reception. The fix is to re-route the WiFi antenna, but in order to do that you need to partly disassemble your device and remove the back.

Further information can be found in this android forum post.

Bumping DRAM clock
Most allwinner devices happily accept 480MHz as the DRAM clock, yet the DRAM tends to be clocked in the original fex at 360MHz. There is a measurable difference in performance when boosting the DRAM clock.

Edit dram_sun4i_360_1024_iow8.c in the u-boot tree, and change the following:

@@ -4,7 +4,7 @@ static struct dram_para dram_para = { -      .clock = 360, +      .clock = 480, .type = 3, .rank_num = 1, .density = 2048,
 * 1) include 

Now build and install u-boot as in the manual build howto, and your machine will be slightly more performant.

Powerdown with UART attached
The A7HD suffers from the same problem as other A10 devices. When you power down with the UART still attached, some power continues to flow into the device, and it will not power down properly. So disconnect the UART if you need to do a proper power down.

= Adding a serial port (voids warranty) =



Device disassembly
Put the hyundai with the glass front down on a clean flat surface. It is relatively easy to pop the aluminum back off. As always with devices with plastic clips, use a piece of plastic (cut the end off a toothbrush to look like a flat screwdriver for instance), to not damage the device more than needed. Loosen the strips of tape, remove the 8 screws, gently open the two ribbon connectors to the display and the touchscreen, and flip the motherboard to one side, but be careful with the backlight connector.

Now you should be able to see the serial connector.

Locating the UART
The right one is GND, the two in the middle are TX and RX. Attach cables as described in the UART howto.



Cable routing
Run the wires along the battery to the left side of the device, where there is still some space for wires. Make sure that the wires run flat next to eachother along the board so that they fit between the board and the display.

If you like a cleanish job, you can drill a hole in the plastic in the bottom. Do not do the obvious thing, like me, as that is just stupid. Drill a hole near the lower left corner of the screen (red arrow). This way the pressure on the display will be kept to a minimum (uneven backlighting) and the device might fully close again.

= Pictures =

= Also known as =


 * The most common name is Hyundai A7HD, even though the motherboard states RK-S7S01
 * Sold as Cherry Mobility M-728 by the Kruidvat store chain in Holland.
 * Yarvik GoTab Ion 7" (TAB275)

= See also =

Hyundai A7HD online Review