DragonOSD+V2 with RTH - Page 10 - RC Groups
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Mar 24, 2010, 06:49 AM
Registered User
Hi magnetman,

A little unrelated but I'm interested to know what happened. So the autopilot was working and suddenly started a slow spiral. At the same time you could not control the plane at 1km? Could it be possible that something else had gone wrong? Have you tested and configured the autopilot under working conditions?

In the meantime, if you are interested in the DragonOSD+, you should grab one at USD99 while you can. We are down to just a few more units that we are prepared to let go at this price. After that the price will go up to USD130.

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Mar 24, 2010, 06:59 AM
Registered User
Think more these days at this issue, and I would have a different approach being in your shoes. Doesn't mean that any of them is wrong, just different

First, after discussions about the PPM in with several guys who get the promotional offer, I can tell you that they are realy scared about the complications raised to obtain this signal from their (various) receivers, and for one almost nullified the purpose of RTH.
They jumped on this OSD because it seems the most P&P from the bunch, and now they say it is far from this promise.

My approach would be to have two channels input instead the PPM input, analyse permanently the pulses, which actually you do anyway, and decide yourself the failsafe condition, based on the signal health, instead on a failsafe position.
So, you have one additional servo cable, but...
- allow usage of ANY receiver, even the cheaper ones without failsafe
- not require the PPM extraction surgery
- more people happy

"Channel assignment flexibility" - who requested this ? what's so hard to change a servo plug, you do it only once anyway...

Originally Posted by Daniel Wee
Using the PPM stream accomplishes at least two important things:-

1. Reduction of cables. Typically you need one control channel, one rudder or aileron channel, and one elevator channel. This is a minimum of 3 servo cables between the receiver and the OSD. While it may not seem like much, if the two are separated quite a bit, there can be a lot of cables in between, which will contribute to noise pick up, noise radiation, extra weight, and so on. With the PPM stream input, all you need is just one servo cable to replace three or four cables between the receiver and the OSD. This also allows for a smaller OSD board (one of the aims of this OSD is keep it small and light) and simpler installation.

2. Channel assignment flexibility. With just the PPM stream, you don't have to worry about hooking up the wrong channel. All that can be configured in the menu so if you decide to re-assign the control channel on your radio, or the elevator channel, for example, you do not need to re-wire anything in your plane. Just a simple menu change will suffice.

Apart from that, having the PPM signal also allows for more features to be added in the future, without the need for more cabling. It does create a bit of an inconvenience for users of more traditional receivers but at the same time there are benefits that come with it. I do realize that this is the first time such a thing has been tried with an OSD but I have a hunch that this could be the way to go with future OSDs, reflecting the trend that MikroKopter has taken. If nothing else, at least we're innovating and not just producing more of the same.

Some of the goals of the DragonOSD+ were:-
1. affordable so that even if it were destroyed, the pain to the wallet would be less
2. matches the text/graphics quality with full screen (edge-to-edge) display capability
3. black bordered text/graphics for high visibility
4. full graphics engine capable of rendering lines, circles, graphics, etc.
5. multi-font support
6. small and light so that it can fit into small planes
7. energy efficient with wide power supply range without getting hot, heavily filtered
8. fewer cables to hook up for RTH capability
9. user upgradable firmware, without need for special programmer
10. universal peripheral/sensor bus that can take many devices easily
11. huge logging capability (this OSD will log multiple flights and you can download to Google Earth files)
12. audio alert capability
13. expandability and device flexibility (will accept different types of GPSes, for eg.)

The idea is to have the above full-featured OSD at a price of much lower featured OSDs. And to have the quality such that even without the RTH features, it would still outperform and outprice other non-RTH capable OSDs. Truth is it was hard trying to get all of that into one small package and in the process, one of the decisions that had to be taken concerned the PPM-stream input.


p.s. From a software point of view, some of the goals were:-
1. "uncluttered look" philosophy
2. user can select multiple styles (eg. you can select from 3 or 4 compass styles, etc.)
3. screen display configurability
4. can be configured in-flight
5. can also be configured via serial terminal
6. sensors/devices auto-detection
Mar 24, 2010, 07:13 AM
Questionable judgement
bracky72's Avatar
Or you can just use a DL rx and not worry about it.

This osd really adds value to the DL purchase since they compliment each other.
Mar 24, 2010, 07:18 AM
Registered User
Sure, how stupid I was to miss that point
Should I mention I reject any mfr where I see the least intention to condition the purchase of a product to the usage of another ?
Mar 24, 2010, 07:21 AM
Registered User
Hi Renatoa,

I realize that this is something new for people but I think once they become more comfortable with it, it should not be that much of a problem. If you think about all the people flying the MikroKopter, they've all done the same thing. And they don't have a problem with it.

Having said that, I do recognize the change and have mentioned this in several places. As much as I would like to make something simple and PnP, I am not sure it is possible to make something this complex with so many options be pure plug-and-play. Often when designing anything, one has to take into considerations the balance of features. Sometimes taking on one feature will prevent another. In the case of DragonOSD+, size was a major challenge. I wanted to make something really small and light. Adding more inputs would have meant a bigger MCU and bigger board.

When considering this particular feature, I was thinking like this - for this price, no other OSD has the RTH feature and most cost more, some a lot more. So even if the user thinks of it as an RTH-less OSD, it would still be a very good deal for them. Therefore, if they now have an option with RTH, it would be a bonus - on top of the small size, low cost, and logging, and the many other features. The need to use PPM seems like a small problem compared to the feature set. In fact, I don't think any OSD has this feature set, even up to twice it's price.

For instance - which OSD has logging? This is the ability to log all your flights and preview it later in 3D in Google Earth. And this has capacity to log multiple flights. Which OSD has RTH? Support multiple GPS types, sensor types, and so on ...

In the light of this, I would think that PPM, while a little new and strange for some users, isn't as big a problem as it may initially seem. There many ways around the problem, even if they could not modify their receiver. At some point in the future, I will probably make a full-blown UAV controller where size would not be such a big consideration - perhaps there, and then, I may add the ability to read servo channels. Right now there just isn't any space to squeeze all that in the board.

Lastly, I'm just doing this because it is something I want to do. Users have many choices and if they find another OSD that meets their needs, they should be free to buy and use that OSD. And if the DragonOSD+ fills a specific price-performance need, then by all means use it. I do this for fun primarily and as an FPV community service and I'm happy that there are other OSDs around. The more the merrier for the users.

Mar 24, 2010, 07:22 AM
Questionable judgement
bracky72's Avatar
I agree it's not a perfect situation but if you happen to own both products...

I really think using ppm is the way of the future so I don't think this is pure marketing.

Eagletree offers logging and multiple sensors btw.

My last real wish for dosd+ is that you can move each element around the screen to the spot of your choosing like rembizi osd allows.
Mar 24, 2010, 07:28 AM
Registered User
Thomas's LRS will also put out a PPM stream. So this isn't just DL users.

I don't know if the ET product with OSD costs USD99 (or even USD130). That's my point - I'm trying to make some of these features available at lower prices than ever before. Comparing apples to apples, I think the DragonOSD+ makes very good sense and excellent value for money.

As for the moving of the screen elements, I will consider it but no promises. I have to admit that I am quite comfortable with the current layout options. However, all that is just a matter of different software and right now my main priority is to get the IMU working for the DragonOSD+.

Mar 24, 2010, 07:38 AM
Questionable judgement
bracky72's Avatar
Yes please get the imu perfected.
Mar 24, 2010, 07:40 AM
Registered User
I should add that some of the features I plan to implement will be very tricky without the PPM input, such as those involving V-tails or flying wings. Having the entire PPM frame available to the OSD is a really useful thing. For example, in the DragonOSD+, you can now inform the OSD which channel your flaps channel is and it will indicate on-screen that the flaps are active in case you accidentally left it activated. Something like this would a major hassle to accomplish without PPM frame data. Again, there are many advantages. Less wires means less interferences, less weight, less clutter in the plane (a major one for me since I hate the ratsnest of cables), less things that can go wrong.

As for locking in to DragonLink - think about it. This OSD will work with GPS'es most of the other guys uses and sells. It will work with Sparkfun, Pololu and DIYDRONES sensors. The whole philosophy is to make it as compatible as possible and give users as many options and choices as possible. I don't think you can insinuate that this was meant to be locked into the DragonLink system. What kind of marketing sense is that?

Back in the early days of FPV, we had to make everything ourselves - I don't think PPM-in is too much to ask for all the advantages that it offers.


p.s. This reminds me of the whole maintaining backward compatibility thing of the early Windows versions.
Last edited by Daniel Wee; Mar 24, 2010 at 09:42 AM.
Mar 24, 2010, 08:18 AM
Registered User
Originally Posted by bracky72
Yes please get the imu perfected.
Mar 24, 2010, 08:26 AM
Registered User
Originally Posted by bracky72
Yes please get the imu perfected.
I felt like at start most people did not care as much as I did but obviously everyone else is requesting that =)
Let's hope!
Mar 24, 2010, 11:23 PM
Registered User
barok's Avatar
my tx futaba 7c and rx castle creation berg7 .. do i need to hack the tx and rx to get this ppm signal for the osd to work..
Mar 24, 2010, 11:33 PM
Registered User
Barok, I am not too sure about the Bert7 but take a look at the following file for the Berg4L. If it is similar, then the modification is very easy.


Notice that it says there that the Berg 7 will work. You don't need to do anything to the TX.

Last edited by Daniel Wee; Mar 24, 2010 at 11:38 PM.
Mar 24, 2010, 11:57 PM
Registered User
barok's Avatar
ok simple enough..my soldering skills are ok.. i see a single wire (ppm)..says 5v and ground..where would i get that in the rx or does the osd require this 3 wires signal(ppm), 5v,gnd or just the ppm wire..
Mar 25, 2010, 12:34 AM
Registered User
The 5V and ground can come from any of the normal servo ports. A typical servo cable has 3-wires. These are usually Ground (brown/black), 5V (red), and signal (orange/white). You can use the 5V and ground but please be careful to wire it all up correctly. Other than that, the mod is actually very easy and almost anyone who knows how to solder a wire can do it.

Last edited by Daniel Wee; Mar 25, 2010 at 01:31 AM.

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