Monday, July 28, 2014

RK2928 wireless TV dongle

I recently purchased a wireless TV dongle for $18 (10% off the regular $20 price).  Now they're even selling for $16 on Aliexpress.  For power a microUSB-USB cable is included to plug it into a USB port on the TV or into a USB power supply.  If your TV supplies 5V power to the HDMI connector (most TVs don't), the dongle will draw power directly from the HDMI port.

It came with a single sheet double-sided "user guide".  There's no reference to the manufacturer, though after some searching I found it is functionally identical to the Mocreo MCast.  I found the setup somewhat confusing, as the dongle works in either miracast or DLNA/AirPlay mode.  Pressing the Fn button switches between modes.

The miracast mode is used to mirror your tablet or phone display to the TV.  Android 4.2 and above supports miracast.  In 4.4, it's a display option called "Cast screen".  The dongle appears as a wifi access point (with an SSID of Lollipop), and to use miracast you must connect to this access point.  This would be quite useful for presentations.  I used to do corporate training, and a dongle that can plug into the back of a projector avoids the problems associated with long VGA or HDMI cables.  Miracast is not fast enough for smooth video playback - for that you need UPnP/DLNA.

To setup DLNA, it is necessary to first connect to the Lollipop access point, and then browse to the IP address ( of the dongle.  The configuration page allows you to scan for your wifi router, and provide the password to connect.  When you are done, you'll have to switch your tablet connection to your wifi router.

At this point, if you don't have a UPnP/DLNA server and control point, you won't be able to do much with the dongle, since it's not Chromecast compatible.  XBMC is a popular DLNA server, and even Windows 7 includes a DLNA server.  Media players like the old Seagate Theatre+ will also work as a DLNA server if you have an attached hard drive.

Once you have a server, you'll also need a controller aka control point app for your android device.  The manual that came with my dongle recommended iMedia Share, but this app only supports sharing media that is already on your tablet.  Finding a decent app was rather frustrating, as the first couple free apps I tried, such as Allcast, are basically a teaser for the paid app.

After some searching I found Controldlna which does (mostly) work.  I was able to browse my DLNA server, and direct the dongle to stream video from the DLNA server.  The play/pause function in controldlna was flaky (frequently stopping the video rather than pause), so I had to use the dongle's web page controls.  Similar to the dongle's setup page, there's a page that has play/pause/stop buttons.

Playback of a 1mbps h.264 encoded HD video was very smooth.  There was a problem with the aspect ratio though.  The video was 2.25:1 aspect ratio, but the dongle displayed it at full screen 16:9, making the video look vertically stretched.

What is lacking is the ability to browse online videos (like youtube) and direct the dongle to play them.  The DLNA protocol supports arbitrary URLs, so the only barrier to playing online video is a control point app that allows selecting videos from the web.  If I can't find one, it may be time to see how my Java coding experience translates into writing Android apps.

The dongle has lots of potential, but the software is lacking at this point.  Although it's not something for your average person who wants to watch digital video on their TV, for the technical folks I think it's worth the money.


  1. I have a similar, only without the wifi antenna. I managed with success with the APP Allconnect together with the APP Web Video Caster; I open the page with video by Web Video Caster and play the video, send forward to the allconnect. In Allconnect I can send to the tv link online video. I do not know why the Web Video Caster does not work when trying to send to the TV. luckily this app has a forward function to another program. It works great, but not all online videos he finds, perhaps the program I use is not so perfect. I'm looking for a newer firmware, my comes with Wifi display R3.0.5rc. Maybe some more current firmware fix this incompatibility with some programs. sorry my english, I'm from Brazil. Thank you for sharing your experience.

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  3. Hello,
    Did you ever figure out how to fix the Aspect Ratio issue?

    1. No. I haven't used the dongle in over a year now. Android no longer supports miracast, so Chromecast compatible dongles are a better option now.