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March 17, 2011 11:26 PM

Categories: Rovio Development

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ScribbleJ

Member
Joined: 03/17/2011

I know a lot of people are going to want to do this, and I've had a really hard time finding any evidence that anyone has done it already.  I hate doing more work than I have to though, so if anyone HAS done it already, please let me know.

I have constructed a duplicate home station for my Rovio, which it recognizes as beacon #0, just like its actual home.  This is a good start, but I only have the home station, no beacons, so I'm having a hard time guessing what values I need to create stations 1-9.

Here's what I've learned so far:

The Northstar system used in the Rovio uses two infrared LEDs; we all know this.  The LEDs are programmed to flash with a 50% duty cycle, at various speeds.  The different speeds tell the robot which station ID it is looking at.

My suspicion is that only one LED's blink rate changes when you change IDs and the other is constant.

I opened my base station and opened the Northstar unit inside it.  By applying a 100Mhz, 2-channel oscilloscope to the two LED-powering transistors, I was able to easily read the values used by the base station for channel 0.  They are (as near as I can measure) about 2.01Khz and 3.03Khz.  These have a common denominator of 165microseconds.  If I wire up two infrared LEDs to blink, one at ~2.01khz and the other at ~3.01khz with a 50% duty cycle THE BOT RECOGNIZES IT AS NORTHSTAR BEACON #0.

All I need to produce a schematic for a complete, working beacon is the values for the blink rates for channels 1-9, and we can all have as many beacons as we feel like making at home.

So - has anyone out there got a beacon, an oscilloscope, and about ten minutes to test it and write the values down here?  If you need any help I can give precise directions.

Discussion:    Add a Comment | Comments 1-15 of 29 | Latest Comment | 1 2 Next »

March 17, 2011 11:30 PM

If anyone's upset this isn't an actual how-to, I'll be happy to post what I have so far, but it isn't very useful to produce a second station #0.

March 18, 2011 3:14 PM

Let's hope somebody can help you out, I am dying to build myself some beacon's as they are not sold anymore... :(

March 18, 2011 3:31 PM

The KHz seem conveniently arbitrary numbers. I wonder if more base station codes would pop up if you tried a few frequency combinations; 3.5 and 4.5 khz, 5 and 6, etc. I would think both frequencies would need to be different from every base station or there would be a chance of mixup.

I'd start with the 2 and 3 KHz, and try to ramp up both frequencies equal amounts to see if the beacon code changes.

March 18, 2011 10:59 PM

EUREKA!

I wrote some software and built a little rig to try various frequencies. After trying multiples of 165us and 1khz, I wasn't getting anywhere. So I sat down and wrote an automated scanner that would just try every possible combination of frequencies, polling the bot for it's signal strength.

Well, to make an ongoing story short, IT WORKED. I'm still in the process of tuning the fuzzer and graphing out the complete number space, but I couldn't resist jumping ahead for a quick test - and I now have what I believe is probably /NOT/ the 'real' ID for nav station 1, but it is a frequency that /works/ as nav station 1 - until I have the space mapped out and can figure out the pattern.

That frequency is 3150hz on one LED and 4255hz on the other.

I'll give more news later when I've had more time; was just too excited. Incidentally, I'll be posting pictures and more info at: http://www.thingiverse.com/thing:7101

March 18, 2011 11:41 PM

Are you in the U.S.? I have a spare Beacon I can let you borrow.

Rovio Commander IIRecord Video, Motion Detect, Sentry Paths and more. All features built in. http://www.robocommunity.com/download/15769/_New-Rovio-Commander-II/

March 19, 2011 1:18 AM

cowboyctx - I'm near Chicago. But this is going SO WELL I may not need it... I'll let you know tomorrow. Thank you SO much for the generous offer!

March 19, 2011 6:49 PM

Try these pairs of frequencies in Hertz:

3030 and 2010 (you already measured these)
3150 and 2070
4170 and 3210
4290 and 3330

If all of these pairs work for you, I think that I can give you the rest of them.

I would like to build my own beacons, too, so please share your circuit schematic.

Botman

March 20, 2011 12:46 AM

Botman said: Try these pairs of frequencies in Hertz: 3030 and 2010 (you already measured these) 3150 and 2070 4170 and 3210 4290 and 3330 If all of these pairs work for you, I think that I can give you the rest of them. I would like to build my own beacons, too, so please share your circuit schematic. Botman

Botman - I responded to you over on Thingiverse -- the short answer is they do seem to work.  Where'd you get this information; and what's the rest of it?

I'll be sharing a circuit on the thingiverse as soon as I've got a working set of frequencies and have had time to build a circuit that's good for more than just testing. :)

May 28, 2011 11:06 AM

It's so awesome that you guys have figured out how to reverse engineer the beacons, because I just bought a Rovio a couple of weeks ago and found myself in the same boat you're in, when I realized the beacons are no longer for sale (despite still being advertised on Wowwee's website).

I'm a web developer in Florida, and I've been interested in robotics for as long as I can remember. So when I discovered Rovio and all it can do, for a price that's pretty affordable, I was ecstatic.

As a web developer, I have the programming skills to work with Rovio's API, but unfortunately, I know next to nothing about electronics, so most of the information you're discussing about the hardware is way over my head.

I apologize for the slightly off-topic post, but do any of you know of any websites, books, or other resources you could point me to for a beginner's introduction to electronics (any anything else I'd need to learn to be able to hack my Rovio)?

I'm really eager to build hack the Rovio and make something cool, but I don't even know what I need to learn first, let alone where to find it. Any advice you guys could offer me would be greatly appreciated.

Thanks in advance!

June 9, 2011 12:20 PM

My question is, why does wowwee have a full blown northstar transmitter in the base station and beacons? I have successfully used a 556 and two IR LEDs to produce the same effect. If you look at the base station PCB, you'll notice that there is room for a slide contact for 9 (I think it was 9) positions, (that is 9 ids). I think that you need to populate some pads and remove a resistor to make the slider work though. There is also a pair of pads to select 60 or 50HZ.
I haven't read through the thread completely, but according to the app notes of the northstar system (available from the manufacturer) and by trial and error, only one LED is required to receive the beacon ID. There are two frequencies so the rovio can tell which direction the beacon is facing (front to back or back to front).

August 11, 2011 4:41 AM updated: August 11, 2011 4:41 AM

Great discoveries afoot here guys. I'm interested in this development. One of the problems I have found is that people (or cats) tend to knock the beacons when they are sat on the floor and thus disrupt the navigation paths the next time the Rovio is used. I was considering mounting fixed IR LEDs in the ceiling of some of the rooms but wasn't sure if this is a viable option. The LED's could be fairly discreetly mounted and I would think be unobtrusive. If there are any circuit designs, schematics, could you please let me know. I also have a single TruTrack beacon which is European spec (50Hz) so if you need photo's for comparison, let me know. Keep up the good work guys.

January 12, 2012 4:09 PM

Here's a link to a project page that shows a simple two LED setup driven by a 556 dual-oscillator.
http://www.botmag.com/articles/scribbler.shtml

If we put that together with the info provided here...
http://www.thingiverse.com/thing:7101

There should be a simple was to create a beacon.

January 31, 2012 5:36 AM

ScribbleJ said: I know a lot of people are going to want to do this, and I've had a really hard time finding any evidence that anyone has done it already.  I hate doing more work than I have to though, so if anyone HAS done it already, please let me know. I have constructed a duplicate home station for my Rovio, which it recognizes as beacon #0, just like its actual home.  This is a good start, but I only have the home station, no beacons, so I'm having a hard time guessing what values I need to create stations 1-9. Here's what I've learned so far: The Northstar system used in the Rovio uses two infrared LEDs; we all know this.  The LEDs are programmed to flash with a 50% duty cycle, at various speeds.  The different speeds tell the robot which station ID it is looking at. My suspicion is that only one LED's blink rate changes when you change IDs and the other is constant. I opened my base station and opened the Northstar unit inside it.  By applying a 100Mhz, 2-channel oscilloscope to the two LED-powering transistors, I was able to easily read the values used by the base station for channel 0.  They are (as near as I can measure) about 2.01Khz and 3.03Khz.  These have a common denominator of 165microseconds.  If I wire up two infrared LEDs to blink, one at ~2.01khz and the other at ~3.01khz with a 50% duty cycle THE BOT RECOGNIZES IT AS NORTHSTAR BEACON #0. All I need to produce a schematic for a complete, working beacon is the values for the blink rates for channels 1-9, and we can all have as many beacons as we feel like making at home. So - has anyone out there got a beacon, an oscilloscope, and about ten minutes to test it and write the values down here?  If you need any help I can give precise directions.
 

After a bit of thought I was wondering firstly if you could find time to edit your original Thread intro to take into account all the information we are gathering here.

I get the feeling that your/this Thread could become vital in the future development of Rovio itself. Together the Rovio community seems to have amassed just about everything there is to allow hardware and software development/hacking of this cool little robot. There is however a bit of a gap regarding the base station and beacon despite this excellent report by Peter Redmer and hack by Thingverse or DIY beacon by ScribbleJ. There is also a brilliant thread (Inside Rovio) by tome. It would therefore be particularly advantageous for us all to co-ordinate our online community to take Rovio forward now that the manufacturers have backed out.

Any ideas or propositions here would be much appreciated. For instance could we bring together a development team which is funded by everyone in some way rather than highly knowledgeable individuals making a quick buck with bespoke software (roviocommander etc)?

The crux of this post is community co-ordination so any ideas or proposals are very much appreciated.

RoboaRovio

Sociorobotics Blog: http://sociorobotics.wordpress.com ~ Wikipedia: http://en.wikipedia.org/wiki/Sociorobotics

January 31, 2012 5:52 PM updated: January 31, 2012 5:55 PM

vinnie said: Here's a link to a project page that shows a simple two LED setup driven by a 556 dual-oscillator. http://www.botmag.com/articles/scribbler.shtml If we put that together with the info provided here... http://www.thingiverse.com/thing:7101 There should be a simple was to create a beacon.

Hey Vinnie, ScribbleJ

Do you think that another base station in each room would work as another beacon, would it be possible/easy to configure in some way? Particularly as Rovios are now coming onto Ebay at such good prices?

Sociorobotics Blog: http://sociorobotics.wordpress.com ~ Wikipedia: http://en.wikipedia.org/wiki/Sociorobotics

January 31, 2012 10:14 PM

Hey Vinnie, ScribbleJ Do you think that another base station in each room would work as another beacon, would it be possible/easy to configure in some way? Particularly as Rovios are now coming onto Ebay at such good prices?

Zinkoxyde noted the contacts on the PCB of the base station beacon- I'm fairly sure it is the same PCB as used in the room beacons. On the room beacons there's a slide collar with a contact to let you set the ID- so putting a jumper on the appropriate pads should set the ID. I'd have to dig out my old pix of the PCBs to be certain. Also, Nocturnal and I spent a fair amount of time mapping the ID frequencies and figuring out the conversion from the LED projections on the ceilings into the Rovio nav units; I don't even remember if we published any of that here (!). I used a Parallax Prop demo board to drive two IR leds that I taped up on the ceiling. I can try to dig out the old notes (we moved house since then and I no longer have the Rovios) if anyone is interested.

Oh and PS I've tried pinning a few of these good resource threads- they should stay at the top of the forum list now but let me know if it doesn't appear that way to you.

cheers- Scott

Discussion:    Add a Comment | Back to Top | Comments 1-15 of 29 | Latest Comment | 1 2 Next »

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