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Old Jul 17, 2012, 02:13 AM
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Originally Posted by PhracturedBlue View Post
It will be helpful to get high-res pics of the motherboard. It is very likely that the flash uses an identical interface. However, a few of the routines I've written will need to be tweaked, since I block-out the bootloader image so that the filesystem doesn't make the bootloader look ugly. Sicne the Devo10 likely has no bootloader image, you won't need that hack.
Oh... Different flash, same SPI interface, got it.
Oh BTW, how did you manage to find out the memory map for the Devo8?
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Old Jul 17, 2012, 05:56 AM
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Just stumbled over this Devo 8 with free Heli included and had to order for that price:

http://helidirect.com/walkera-v100d0...ge-p-24760.hdx
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Old Jul 17, 2012, 09:19 AM
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Originally Posted by magic_marty View Post
wow you really no your stuff cause its only been a couple of days when you started the 2801 project...

very nice and please keep us posted on the progress ...

great work your doing, myself and others really thank you for your efforts..
I have to admit that PhracturedBlue works fast, I am also quite impressed with his documentation of the protocol. That sort of information is not only good for the DEVIATION firmware, but is a very complete description for people willing to know more about the different 2.4GHz systems out there.

For instance I am a bit disappointed to see that all wk2x01 systems use always the same SOP code (DSSS code). All other systems (including the DEVO) have some degree of diversity in code use. This might come as an issue if a lot of people in the field have the Walkera equipment. Maybe they were not counting on selling too many

I also wander if Walkera suffers from the same issue affecting some DSM2 systems, that is, choosing RF channels that are very close to each other, hence loosing a fair amount of narrow band interference immunity
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Old Jul 17, 2012, 09:45 AM
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Originally Posted by renatopub View Post
I also wander if Walkera suffers from the same issue affecting some DSM2 systems, that is, choosing RF channels that are very close to each other, hence loosing a fair amount of narrow band interference immunity
Well, at least with the Walkera radios, the channel selection rules are not defined by the protocol. That means we can choose whatever algorithm we like to choose the frequencies in use. This is unlike the Flysky protocol (and I think DSMX) where the hopping sequence is pre-defined (though there are many allowed sequences). Of course using a sequence of 12 or more frequencies may bring additional robustness to those protocols.
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Old Jul 17, 2012, 10:21 AM
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Originally Posted by PhracturedBlue View Post
Well, at least with the Walkera radios, the channel selection rules are not defined by the protocol. That means we can choose whatever algorithm we like to choose the frequencies in use. This is unlike the Flysky protocol (and I think DSMX) where the hopping sequence is pre-defined (though there are many allowed sequences). Of course using a sequence of 12 or more frequencies may bring additional robustness to those protocols.
In your "Devo.txt" you say:
The transmit channel is changed every 4 packets. It appears to cycle between 3
values, 4 channels apart. For instance:
0x04, 0x08, 0x0c, 0x04, 0x08, 0x0c, ...

Is that channel separation confirmed or a suspicion? It would be silly for Walkera to actually impose a short distance between channels (IMHO).
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Old Jul 17, 2012, 10:31 AM
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Originally Posted by renatopub View Post
In your "Devo.txt" you say:
The transmit channel is changed every 4 packets. It appears to cycle between 3
values, 4 channels apart. For instance:
0x04, 0x08, 0x0c, 0x04, 0x08, 0x0c, ...

Is that channel separation confirmed or a suspicion? It would be silly for Walkera to actually impose a short distance between channels (IMHO).
I don't think it is a requirement. I think it is more likely to be the minimum separation. I just didn't have enough interference to get the Devo to pick other options (I could see it choose other channels if I turend on other Tx in the house, but not a large variety). Still, from the protocol specs, I think it can support any 3 channels, and it is easy enough to test now that I've got the protocol coded.
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Old Jul 17, 2012, 03:32 PM
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Is it possible to get it to hop frequencies after binding?
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Old Jul 17, 2012, 03:49 PM
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Hi.

If there are people interested in the resolution of the problem about powering on and off the transmitter, that I have talked about some time ago.

I have returned from holidays and I have received the components for the repairment of the transmitter.

I have replaced the P-MOSFET transistor and the other two transistors (Y1 and Y2) involved in the control of the power on and off, and now the transmitter runs OK. Now, powers on without problem, and powers off without problem, power-off takes around 6 or 8 second between the movement of the switch till the visualization of the message of power-off, but now it is capable to power-off by himself.

I don't know what could be the problem with the delay in the power-off, but now the transmitter runs enough to be used.
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Old Jul 17, 2012, 03:50 PM
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Originally Posted by Tripert View Post
Hi.

If there are people interested in the resolution of the problem about powering on and off the transmitter, that I have talked about some time ago.

I have returned from holidays and I have received the components for the repairment of the transmitter.

I have replaced the P-MOSFET transistor and the other two transistors (Y1 and Y2) involved in the control of the power on and off, and now the transmitter runs OK. Now, powers on without problem, and powers off without problem, power-off takes around 6 or 8 second between the movement of the switch till the visualization of the message of power-off, but now it is capable to power-off by himself.

I don't know what could be the problem with the delay in the power-off, but now the transmitter runs enough to be used.
To fix the power off problem I just use a BEC set to 6v.
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Old Jul 17, 2012, 04:32 PM
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Originally Posted by PhracturedBlue View Post
In case folks aren't following the project in the other thread, I've just about wrapped up the implementation of the WK2801/2601/2401 protocols into the Deviation firmware. There is still a lot of testing to do, but we're about 90% of the way there (from a protocol standpoint) to supporting the old protocols on a Devo.
Just wanted you to know: it's amazing! I Hope it will work

Many of us have great Helicopters with "old" receivers like CB100, 4G6S, V120D05 and many more. It would be great to have a nice highly customizable LCD Touchscreen Tx like Devo 8 for those.

I'm especially interested in your GUI / UX Design for the firmware, because this part is the most important one for the user.
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Old Jul 17, 2012, 04:39 PM
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Originally Posted by NorCalMatCat View Post
Is it possible to get it to hop frequencies after binding?
I'm not sure what you mean. You mean select 3 different frequencies than those initially selected on power-on? No I don't think you can do that although it is theoretically possible with the Devo protocol since each packet contains the next channel to use. However, actually using that feature would be less robust, since a Loss Of Signal at just the wrong time would result in your model falling out of the sky....

If you mean to bypass the binding period on startup, you can use a fixed-id, but you still need to wait for the Rx to see the Tx, and once it has found it, the channels are fixed and won't be changed.
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Old Jul 17, 2012, 07:49 PM
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Originally Posted by PhracturedBlue View Post
I'm not sure what you mean. You mean select 3 different frequencies than those initially selected on power-on? No I don't think you can do that although it is theoretically possible with the Devo protocol since each packet contains the next channel to use. However, actually using that feature would be less robust, since a Loss Of Signal at just the wrong time would result in your model falling out of the sky....

If you mean to bypass the binding period on startup, you can use a fixed-id, but you still need to wait for the Rx to see the Tx, and once it has found it, the channels are fixed and won't be changed.
No I was thinking frequency hopping, I.E. if it sees a lot of noise on a channel it's using find a quiter one and use that.
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Old Jul 18, 2012, 04:06 AM
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Originally Posted by NorCalMatCat View Post
No I was thinking frequency hopping, I.E. if it sees a lot of noise on a channel it's using find a quiter one and use that.
All Walkera radios already use frequency hopping with 3 different radio channels. But for what I understand of FHSS it is not about constantly trying to find a quiet channel. The hopping sequence is normally kept for an entire session. Changing channels randomly on-the-fly would increase the chances that Tx and Rx get out of sync for not much gain. Besides you would need to know the channel occupancy at the receiver location which can be different from what you measure in the TX. I tell you all that because I have actually thought about such strategies in the past, but it always sounds to me as too complicated and failure prone for little gain.

Enhancements for commercial protocols as to come up with a custom solution are interesting but very tricky. From a superficial point of view, it looks to me that using more channels, like DMSX and FASST do would improve immunity in busy areas. But all design choices have up and down sides.

If you read the amount of discussion on which brand has the best protocol... it is an endless discussion with lots of subjective opinions. I see several scenarios with different challenges where this or that protocol will win, for instance:
1- Crowded field with lots of radios from the same type (2801 lack of SOP diversity could be a minus)
2- Building areas with multi-path hell (Spektrum with satellite receiver could help by providing spacial diversity, that is, when one receiver gets destructive interference the other could still be in the constructive interference zone avoiding loss of signal AKA fast-fading)
3- Long range (for the same power, a high code gain by using DSSS with more chips per bit would help, quality of RF stage design should make a big difference here, error tolerance and fast recovery after loss of signal could also help)

So, how much would it help to increase the number o FHSS channels? What is the trade off between immunity, data rate, resistance to fast-fading, recovery from signal loss....... For some reason most brands in the past (all but Futaba as I recall) chose 2 or 3 frequencies only. Why not using more as it is just a matter of programming? No idea. Intuitively I would say the more the merrier, but I assume the choice was done for a reason.

But once the DEVIATION firmware is up and running, guess it wouldn't hurt to try things out. Well, it might hurt the model and a few innocent people passing by, but progress has it's costs
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Old Jul 18, 2012, 04:15 AM
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Hello!

PhracturedBlue, thank you for your nice work!

A question about Devo 12(s). I've seen pictures of its (?) board. and it looks more complicated than Devo 8 (more chips). Has someone identified all these chips? I can't see markings on the photo. Does it really have the same STM32F103VCT6 ? The ARM chip seems to be bigger?

Just curious about the exact difference between 8 and 12.
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Old Jul 18, 2012, 06:49 AM
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Yet another Feature suggestion

Modern Walkera Quads like QR Ladybird or, propably, the new Hoten-X*, fly very stable. There's no need to correct permanently.

http://www.rcgroups.com/forums/showthread.php?t=1693774
http://walkera.com/en1/particular.jsp?pn=Hoten-X

Theoretically, one could send programmed stick controls to the Quad to make it automatically fly a Pattern or even a Loop or perhaps even a series of different Stunts What do you think?

I would also like to produce a Music Video with dancing Quads... Is it theoretically possible to use the DSC plug to send Audio to the Tx and make a Quad react to the Beats wit slight Cyclic alterations?
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