CNXSoft – Embedded Software Development

In some circumstances, for example by installing the wrong firmware or doing something wrong by playing god (as a root user), it’s possible to brick your device. This happened to me with one of my Droid Stick A2 mini PCs based on AMLogic AML8726-MX. I changed some files in /system/etc/permissions directory, lost Wi-Fi access, and even  replacing my changes with the backup files would not solve the problem. It also changed some permissions in the system, and it was not possible to restore the firmware the usual way. At the end of last month, dbtablets left a comment with download links to “Amlogic USB Burning tool”, but  I only decided to give it a try today, and after some efforts I was successful. Just make sure you only use this method as last resort, i.e. a standard firmware upgrade does not work, and you’re about to throw your device in the trash bin, because you could brick your device if the “resources” file is not for your hardware. The same method should work with other AMLogic AML8726-XX devices but you would have to get the correct resources file from the manufacturer.

The tools are only available for Windows XP or 7. Here are the steps to follow (in theory):

1. Download “Hardware flash.rar” which contains the burning tool, the USB drivers, and the “resources” file, a zip file with the SPL, the bootloader, uImage and update.zip, which is specific to Droid Stick A2. There’s also a word file with instructions.
2. You’ll need to short two pins on the board, so open Droid Stick A2 casing to access the board.
3. Extract Hardware flash.rar in a directory of your choice, enter Hardware Flash/Hardware flash of amlogic directory, and click on ImageBurnTool.exe to start the program.
4. In the top menu click on the first item on the left drop down menu to load the resources file. I had to do this in a netbook with 1024×600 resolution, and following the great “flash tools” tradition, the window cannot be resized, so I could not see the top menu. In that case, simply press “Alt” then “Down Arrow” and “Enter” to access the popup menu to load resources.zip
5. Connect the mini USB to USB cable to your Windows PC but not to Droid Stick A2 yet, short TP14 as shown below, and only then connect the mini USB cable to start your device. N.B.: Some other devices have a recovery button so that you don’t need to open the case.
   
6. Windows should then detect a new device (M6-CHIP), and ask you to install the drivers. To be honest, I’m not sure what you have to do at this point (as I did this many times), but I think you can just press cancel, as the burning tool will install the drivers automatically (in theory) and you should eventually see a “WorldCup device” in the hardware manager.
7. Port 1 line should show the device is connected in the burning tool. Check the option to erase the flash (as shown on the right), and click on the start button (开始) on the top right of the window to start erasing the flash. For me the process connected to both Port 1 and Port 3, it failed on Port1, but was eventually successfully on Port 3.
8. Disconnect and reconnect the USB cable from your PC, it should start upgrading the firmware automatically, and having a while you should see “Success” in the window. Again, for me Port 1 failed, but Port 3 worked OK.

Once this is done, connect Droid Stick A2 to your HDMI TV, and it should start normally with a relatively recent firmware (30th of January 2013). Apparently the method above worked just fine for some people, but it did not work for me, as the system refused to install the drivers (Step 6). I tried in a virtual machine Windows 7, and a netbook running Windows XP SP3, and the drivers refused to install either automatically thru the burning tool, or manually with the drivers in Hardware Flash/Hardware flash of amlogic/AmlogicusbBurningdriver directory. So I decided to look for alternative drivers, and found another version of the burning tool in Slatedroid. So I download the file (AML_Flash_tool.rar), extracted it, and instead of starting ImageBurnTool.exe, I clicked on ImageBurnTool-sp3.exe as my netbook runs Windows XP SP3. AML_Flash_tool.rar only contains the burning tool, so I used resources.zip for Droid Stick A2 from the first rar file. The program managed to install the “M6-CHIP” drivers automatically, but then the procedure would fail during steps 7 or 8, as SPL would not load for some unknown reasons. After several retries however, the procedure went through successfully (don’t ask me why) and I could recover my device, although as mentioned previously it ended with an error on Port 1, but successfully on Port 3.

Since I’ve been asked, I’ve done a short video showing how to open an Android mini PC, namely Droid Stick A2. As most casings are based on similar design the same method can be used for many other mini PCs that comes with a plastic casing. Some other mini PCs with a metallic casing, such as Hi802, need to be opened with a different, and IMHO easier, method as you just have to remove 2 screws.

For Droid Stick A2, all you need is a flat head precision screwdriver. First look for small spaces between the two parts of the casing, insert the screwdriver where the largest space is, and gently lift it up. Watch the video below for a demo.

Droid Stick A2 mini PC does not come rooted, so here’s a simple rooting guide for the device. First, make sure you’ve installed the latest firmware, then follow the instructions below (Source: ARMTvTech):

1. Copy update_Superuser.zip to the root of a micro SD card.
2. Insert the microSD card to Droid Stick A2, and power the device
3. Go the Apps menu in Android, and launch “Upgrade” app.
4. Select Local Upgrade
5. Select update_Superuser.zip
6. Select Reboot And Install Package
7. Let the update go through, and let it boot to Android.

You should now have root access. This method deleted old version of su and Superuser.apk, copies su to /system/bin & Superuser.apk to /system/app, and changes permissions on those files. It may also work on other AMLogic AML8726-M1 / M3 / MX based devices. If you are interested in knowing exactly what it does, unzip update_Superuser.zip, and open /META-INF/com/google/android/updater-script.

For some reasons, the first time I tried, it failed to create a symlink to su, and after the first boot I got the Android Home Screen for phones, without access to mouse or keyboard. A reboot recovered access to the proper user interface and access to mouse and keyboard. My second try with the steps described above finally succeeded to root the device.

If you have read my previous review of the Droid Stick A2, I was pretty upset about Google Play since I could not install most of the apps. This is now fixed, and Kimdecent has released a firmware upgrade.

Here’s how to upgrade:

1. Download g02refDongle-ota-20130201.rar
2. Extract it in your PC, and copy the files (g02refDongle-ota-20130201.zip and uImage_recovery) to the root of your microSD card (Formatted as FAT32)
3. Insert the microSD into Droid Stick A2
4. Boot the mini PC normally, and launch the “Upgrade” app
5. Select Local Upgrade, then select g02refDongle-ota-20130201.zip and click on Reboot and Install Package
6. Droid Stick A2 will reboot, and it should start upgrading Android.
7. Done

Since I’ve been messing up with Android and broken something, “Reboot and Install Package” does nothing for me (some permissions issues with /cache/recovery/command), so I could not verify this works or not. Finally, I could install it on the first version of Droid Stick A2 and Google Play now works fine.

In the other, newer, stick I’ve bricked (or sort of bricked), I’ve tried to enter recovery mode by shorting the two large pads below TP14 (See pic), and it does seem to enter a special mode, but my TV does not detect any video signals.

At the beginning of December 2012, I wrote a post about Droid Stick A2 mini PC based on AMLogic AML-8726-MX to show some pictures of the device, but I could not really test as the firmware was not complete, and was promise a working firmware soon. Unfortunately, things did not really go according to plans for this hardware, so the firmware never showed up… Luckily, Kimdecent found another version of the device with basically the same specs, a slightly different casing, and more importantly a “working” firmware. The company was kind enough to send me another sample for review.

Droid Stick A2 Unboxing

Here’s what the new Droid Stick A2 and its accessories look like.

Beside Droid Stick A2 mini PC, the package contains a power adapter (5V/2A), a mini USB to USB cable, a short HDMI cable and a user’s manual in English.

A close up shows the device has plenty of ventilation holes, a mini USB and IR connector on one side, and a USB and microSD slot (Not shown in pic) at the opposite side of the HDMI connector.

First Boot, Settings, and First Impressions

Let’s connect a keyboard and mouse to the device via a USB hub, connect the mini PC into the TV, and the power supply to the mini USB port. Within a few seconds, the Android Home Screen should appear.

Android Home Screen (Click to Enlarge)

There are 5 applications available from the home screen: the stock browser, a file browser, music, a (useless) movie player, and the settings.

In the settings menu, we have options to connect to Wi-Fi, VPN and configure it as a portable hotspot. That’s it no Wi-Fi direct and no Ethernet support. As usual, the Wi-Fi connection was easy to setup. The soft keyboard will pop-up even if I have a USB keyboard attached. However, If you don’t like that you can always install Null Keyboard. The display section allows you to choose between 720p or 1080p (default) video output, but the UI is fixed to 720p. There’s also an option to adjust overscan and set the font size. The Developer Options are available , but the device is not detected at all when I connect it to my netbook or PC via the mini USB port. The “About Mediabox” section shows the model number is “MBX Dongle board (g02refDongle)”, that it’s running Android 4.1.2 with kernel 3.0.8.

There are just a few pre-installed apps on the device. This is normally not a problem, but in the current firmware Google Play is just a disaster, and most application will fail with “this item is not compatible with your device”. This includes Antutu, Quadrant, Angry Birds, Subway Surfer, YouTube, Facebook and a few others. The only app I could install from Google Play is ES File Explorer. This should be easily fixable, possibly but adding some files to /system/etc/permissions, but the device is not rooted, and it looks like the mini USB port only carries power, it’s not detected at all in Linux or Windows, even after enabling USB debugging in the settings. So we’d have to wait for a new firmware, or get the existing firmware to add some missing files. I’ve told Kimdecent about this issue, and they are looking into it. The new firmware fixes Google Play, and I could install all applications I tried.

Apart from this rather annoying Google Play issue, the system feels pretty responsive and stable when using the web browser, checking emails and play videos. I’ve tried to power it up from the USB port of my TV, and it can boot to the home screen, but I will reboot at that time. I’ve also powered it from computers when I tried to access adb. My desktop PC’s USB port could not provide enough power to boot it (I used a USB extension cable), but my netbook USB port could. I’m also surprised at how cool the device is during operation.

Video Playback (and Wi-Fi performance)

There are two media players installed:

• ES Media Player
• Video Player

Since Google Play is not working as it should, I used those two players for video playback testing using videos from samplemedia.linaro.org and other sources played via a SAMBA share:

• H.264 codec / MP4 container (Big Buck Bunny), 480p/720p/1080p – OK
• MPEG2 codec / MPG container, 480p/720p/1080p – OK
• MPEG4 codec, AVI container – OK
• VC1 codec (WMV), 480p/720p/1080p– OK
• Real Media (RMVB) – FAIL. But MX Player should be able to play RV8/9/10 samples via software decoding.
• MOV file from Canon camera – 720p videos will stop after a while (due to Wi-Fi performance)
• FLV videos – OK for most.
• WebM – 480p OK, 720p and 1080p Fail.
• MKV (several codecs) – OK. But I could hear some regular audio noise in one video.

Video playback is quite good, as it can play the most common formats, video and audio codecs, without major issues. Sometimes it looks like it starts to play a bit too fast, so the first second may be choppy. However during playback, I had no problem due to buffering except for my camera’s videos, which means Wi-Fi performance is quite good as well. A 278 MB file copy between the SAMBA share to the internal SD card took 4m25s (1.05MB/s), which is still quite slower then Hi802 (1.42 MB/s), but still acceptable with the videos I tested.

I thought one of the main advantages with AMLogic AML8726-MX devices was it could already support XBMC (Android) with hardware decoding. Well, I thought wrong. First, I used XBMC Frodo RC3 for Android, and the UI was very smooth (about 40 fps), but I could not play any videos with hardware decoding. dman left a comment in another post explaining that “There is an official ‘test’ build from XBMC which has HW acceleration across multiple devices.”, so I decided to give it a try and download the latest version in http://ftp.heanet.ie/mirrors/xbmc/test-builds/android/ (xbmc-20130121-3fa9c61-android-hwaccel-armeabi-v7a.apk), but I soon found out that it would not work either, mainly because this version makes use of stagefright which is not supported by AMLogic and AllWinner SoC. I’m pretty sure we’ll eventually get a proper XBMC Android with hw video decoding for this platform, but just not yet, and the only option for now is to use XBMC with an external video player.

Droid Stick A2 Benchmark Results

I’ve installed Antutu 3 and Quadrant on the device with some APKs, and ran the benchmarks.

Droid Stick A2 scores 8461 which is not bad for a dual core processor @ 1.2 GHz, and places the device performance between the performances of a Galaxy SII (Exynos 4210) and Galaxy Nexus (OMAP 4460). There was another annoyance during the benchmark: the screen rotated in portrait mode, which is quite inconvenient on a TV…

It’s one of the rare device I’ve tested, where the Quandrant benchmark can actually run properly, and the results look even better than with Antutu 3.0.3 with a score of 3181.

The information tabs in Antutu and Quadrant show the CPU frequency oscillates between 48 (or 96?) and 1200 MHz, the (UI) resolution is 1280×672, the product and board name is g02refDongle, and there’s a total of 913220 KB RAM.

Droid Stick A2 PCB

Let’s see what’s inside the box, and if there are many different with the first version of Droid Stick A2 dongle.

Top of Droid Stick A2 PCB (Click to Enlarge)

The very first thing that I’ve noticed is that they got rid of the massive heatsink from the previous version, so we can actually more of the top of the board. This side includes two GeIL RAM chips, AML8726-MX, and the Wi-Fi module (WL-211). We can also notice a proper Wi-Fi antenna, which can explain the good Wi-Fi performance of this mini PC.

Bottom of Droid Stick A2 PCB (Click to Enlarge)

The bottom side of the PCB features a microSD socket, the flash chip and 2 more RAM chipsets.

Conclusion

Initially, I was disappointed by the device mainly because of the Google Play issue, and the lack of XBMC hardware video decoding support. But the device actually operates smoothly, video playback is good, and Wi-Fi performance is better than most other mini PCs I’ve tried. So far I’ve found several issues that should be fixable with an updated firmware:

• Google Play – Most applications can’t be installed due to “this item is not compatible with your device”. Fixed with Latest firmware.
• Screen may rotate to portrait mode. Update: You can fix this yourself, by going to Settings->Display, and uncheck “Application request to change orientation”
• Soft keyboard not disabled when hardware keyboard is connected.
• Lack of Ethernet USB dongle support
• Several audio codecs including AC3 have a short “sshhh” sound every 3 seconds or so. See comment for details.
• Update: Few games I’ve tried don’t support “mouse” touch (Subway Surfers, Temple Run 2), but Angry Birds Star Wars worked fine for me.

There are probably other issues since I’ve not tested that many apps. Full hardware decoding for XBMC would certainly be an advantage, although it’s also coming to other SoC such as Rockchip RK3066 thanks to the latest XBMC implementation using stagefright. The (apparent) lack of ADB support via the mini USB port could also be an issue for developers.

Kimdecent sells the Droid Stick A2 for $52.99 so it’s price competitive with Rockchip RK3066 mini PCs. [Update: I've informed that Pandawill sells what appears to be the same device, but called MX6, for $51.99]

AMLogic released the “common” source code for Linux kernel, which means we get most of the kernel source, except the part which is customer specific such as drivers, there’s a XBMC Linux port for AMLogic 8726-M3 processors so video playback and GPU drivers (but maybe not X11 accel) are available for Linux. On the contrary, Rockchip never did that directly for its SoCs, but a company released the GPL source code for a Rockchip RK3066 tablet, which allowed the developers’ community to port Linux to RK3066 mini PCs , and eventually release PicUntu. But video playback and GPU acceleration may be a challenge. It will be interesting to see how popular AMLogic dual core mini PCs become, and if the community builds on the platform.

Droid Stick A2 is an HDMI TV Stick based on AMLogic AML8726-MX dual core Cortex A9 processor, and together with HI-802 (aka GK802) mini-PC based on Freescale i.MX6Q, is the most likely platform to get proper Linux support, as AMLogic AML8726-MX source code is somewhat open, and video playback in Linux is supported in the older AML8726-M1 processor (Cf. XBMC Linux in Pivos STB).

Kimdecent sent me a sample for evaluation, but as the Android firmware is not really ready for prime-time at this time, I’ll just show some pictures of the device, as well as the user interface, and will review the device once a firmware update is available.

Since this is still a sample, I received the device in a white box with the Droid Stick A2, a mini USB to USB cable, a small 5.2V/1A power supply and a plug adapter.

Droid Stick A2 and Accessories

There are plenty of ventilation hole for cooling the device, and this is the first mini-PC I’ve seen that has been designed to be easily attached to a keyring.

Droid Stick A2 has a male HDMI connector, an “Update” button, an IR jack, a 5+V mini USB OTG port, a USB 2.0 Host port and a microSD card socket.

There’s not much we can see from the PCB, as a heatsink almost completely covers the top of the board.

Top of Droid Stick A2 Board – Click to Enlarge

The microSD socket, flash and RAM are soldered at the bottom of the board.

Bottom of Droid Stick A2 Board – Click to Enlarge

Beside the heatsink, they also added 2 heat conductive rubber pads, so it looks like a lot of efforts were put into cooling the device.

Time to put this all back together, insert the mini-PC into the HDMI socket of my TV and connect the power supply. I’ve also tried to power the device with the TV USB port, and the boot will start, but like most other devices (excluding Telechips TCC8925 based devices such as CX-01) the boot won’t complete, so the external power supply is really needed.

Droid Stick A2 User Interface

This HDMI TV stick features a proper media player interface adapted to TV usage with access to music, videos, the picture gallery, a file manager, the stock browser, Android settings and Android apps. The interface is better suited for a remote control than a mouse, and you can’t add shortcuts, so you have to click on the Android doll each time you want to launch an app. The “About MediaBox” menu indicates the model number is MBX Dongle board (g02refDongle), and the current firmware runs Android 4.1.2 with Kernel 3.0.8.