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Old Jul 18, 2012, 09:56 AM
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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.
Which problem is this?
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Old Jul 18, 2012, 10:27 AM
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A problem related with a transmitter that I have purchased and that arrived faulty to me.

But the problem with the power-off seems to be more usual, seems like there are some people that have this problem and they solve it using a LIPO (I don't know if they have also problems with the power-on). I solved the problem with the power-on by replacing the P-MOSFET and the two another transistors related with it. The problem related with the power-off could be related with a high value in the capacitor associated with the switch to power-off or a fugue at it. But for me already it is not a big problem. If I have some time (but without hurry up because to work with SMD consumes much time to me) probably I'll continue testing to find which is the exact problem with the delay in the power-off. I think it has no relation with the P-MOSFET or something related because the delay is before to the visualization of the message of power-off.

PhracturedBlue helped me in searching the P-MOSFET.

Thank you to PharacturedBlue. I think the work he is doing at this thread about DEVO transmitters is very interesting.
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Old Jul 18, 2012, 10:47 AM
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Originally Posted by agalakhov View Post
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.
I haven't seen any detailed images of the12, but I am sure it uses an STM32 based uC. Someone told me they have a STM32F103VCT6 , but I haven't confirmed it with my own eyes. They may use one of the higher-density chips to get more RAM, or because they need more I/O pins, but it won't matter at all from the custom firmware perspective.
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Old Jul 18, 2012, 11:12 AM
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I am interested in the DEVO12S too, as I have ordered one (hope it doesn't get stuck in customs..) that should arrive in a couple of weeks.

Is there anyone else contributing with coding at this point other than PhracturedBlue? I really don't have much spare time, but if it what it takes to get 12S compatibility I could try to contribute but well, no guarantees...

By the way, would anyone have a dissassembly of original Walkera firmware (preferably 12s) that I could take a look?
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Old Jul 18, 2012, 01:33 PM
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Originally Posted by PhracturedBlue View Post
I haven't seen any detailed images of the12, but I am sure it uses an STM32 based uC. Someone told me they have a STM32F103VCT6 , but I haven't confirmed it with my own eyes. They may use one of the higher-density chips to get more RAM, or because they need more I/O pins, but it won't matter at all from the custom firmware perspective.
I see. I've seen some photos with four large chips and a button cell battery on them. One chip is ARM with marking starting with "STM32F10..." but it's obviously bigger than 103VCT6. Another one is "ISSI" so it's probably RAM, and the third one is "Hynix". That resembles an ordinary ARM SBC with flash, RAM, MCU and battery-powered RTC. The 4th chip is mysterious. It's located between RAM and RF module, and I'm afraid it's a second MCU, if so it's completely different

Can some owner of 12s please tell which chips are used?..
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Old Jul 18, 2012, 01:47 PM
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Originally Posted by renatopub View Post
Is there anyone else contributing with coding at this point other than PhracturedBlue? I really don't have much spare time, but if it what it takes to get 12S compatibility I could try to contribute but well, no guarantees...
At the moment, I am the only one doing development, though others have come in and out. FDR has been awesomely helpful in helping get the capabilities and layout done and finding all the bugs. I am open to all offers
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Old Jul 18, 2012, 06:14 PM
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Finished changing out the switches. You will never, ever get the nuts off and back on without making a ring of scratched off paint around the base of the nut. The only way to avoid this would be to use a brand new panel. However with their being removable you could print out your own custom panels.

Didn't use the red switch nuts just used the tool to remove and install the originals. To remove/tighten them you can hold the tool down into the nut with your thumb and give it a 1/8 twist with a pair of pliers.

Later on I'm going to look into printing out a new set of panels with custom graphics and make transparent covers for them before installing and use the red nuts.
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Old Jul 18, 2012, 06:32 PM
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Originally Posted by Atomic Skull View Post
Finished changing out the switches. You will never, ever get the nuts off and back on without making a ring of scratched off paint around the base of the nut. The only way to avoid this would be to use a brand new panel. However with their being removable you could print out your own custom panels.

Didn't use the red switch nuts just used the tool to remove and install the originals. To remove/tighten them you can hold the tool down into the nut with your thumb and give it a 1/8 twist with a pair of pliers.

Later on I'm going to look into printing out a new set of panels with custom graphics and make transparent covers for them before installing and use the red nuts.
Hehe I don't care enough about looks to go to all that trouble for a switch :P My Devo 8 looks like a franken radio anyway (battery velcroed under the support bar, another plug hanging from the battery bay for 2.4 amp, ROFL).
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Old Jul 19, 2012, 08:00 AM
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Total Black Screen

Where can i get Total Black Skin for the DEVO 12s ??
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Old Jul 19, 2012, 08:10 AM
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DEVO 12 Trainer

can the walkera devo 12s train with any other radio ? or does it have to just be DEVO to DEVO ?
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Old Jul 19, 2012, 09:20 AM
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Originally Posted by PhracturedBlue View Post
Here is the deviation firmware binding to a Nine-Eagles Solo-Pro 100 (It also binds to the SP125)
https://vimeo.com/45197356

I have a little more work to do on this one to fully document the protocol (I want to figure out the calculation of the SOP code and CRC and I'm about half-way there now). I don't have any more receivers that are compatible with the CYRF6936 at the moment, so I'll go back to working on the firmware capabilities for a while once I'm done with this one.
OMG you are frekking amazing!! keep it up man im willing to pay for this kinda compatability!!!
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Old Jul 19, 2012, 09:40 AM
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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.
I was taking a look at the DEVO protocol at Deviation repo and this question of freq. hopping from NorCalMatCat came back into my mind.

I noticed from the Devo.txt file that the Rx sends an ack for each received packet, did I get it right? Because if that is the case, there is a much simpler strategy to choose good channels that goes in the line with NorCalMatCat's suggestion.

Something like this:
- Start always in the same frequencies , say 0x04, 0x08, 0x0c.
- Keep using those frequencies until an ack goes missing.
- When one ack goes missing at say, freq 0x04 start transmitting at 0x04, 0x08, 0x0c and ALSO, say... 0x42, indicating in the beacon that frequencies to be used are 0x08, 0x0c and 0x42.
-The new frequency should be chosen using the Tx ID as seed, so that two similar Tx won't start tracing frequencies simultaneously. Very unlikely, but why risk
-As soon as an ack is received for a pack sent to 0x42, it means that the Rx got the next frequency set right, so drop the 0x04 freq and continue broadcast with only 3 frequencies again.
-And so on...

Now if it works or not will depend on the Rx, mainly if ack is really sent all the time, and if it will continue to follow the beacon frequency list after start-up.

I see several advantages. First, there is no need to scan the spectrum at Tx start-up. It will also walk through the entire 2.4GHz band continuously looking for the best channel choices. By using the Ack frame, there is no danger of loosing sync. It is a very simple algorithm, and I actually think this is easier to implement than scanning for RSSI.

I have a couple of Rx802 now, but no Tx yet I really want to try this out. My idea is to take the Tx module out of my old 10mW WK2801 and hook it to an Arduino board. That would be a nice platform to test RF link algorithms. I could even use a second one as jamming source simulator as to test link robustness. Now I am getting way too exited about all this, wife won't be happy
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Old Jul 19, 2012, 10:32 AM
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Austin, TX
Joined Dec 2009
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Quote:
Originally Posted by Paiste2002 View Post
can the walkera devo 12s train with any other radio ? or does it have to just be DEVO to DEVO ?
I can't speak about the 12, but I know that my 8 will only train with an 8--or at least that is what Walkera told me. Doesn't the 12 do wireless training?

Rafa
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Old Jul 19, 2012, 12:58 PM
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Originally Posted by renatopub View Post
I noticed from the Devo.txt file that the Rx sends an ack for each received packet, did I get it right?
No, that is just bad phrasing on my part. It verifies that the transmission was successful, but no ACK from the Rx.
Quote:
Something like this:
- Start always in the same frequencies , say 0x04, 0x08, 0x0c.
- Keep using those frequencies until an ack goes missing.
- When one ack goes missing at say, freq 0x04 start transmitting at 0x04, 0x08, 0x0c and ALSO, say... 0x42, indicating in the beacon that frequencies to be used are 0x08, 0x0c and 0x42.
Changing frequencies with telemetry enabled is a bit more challenging. The Tx is basically a always sending data or waiting for telemetry. you need to know which channel to listen on, or you miss the telemetry data. You don't want to transmit too much data (in either direction) as that will overall mean fewer radios can operate concurrently.
Also remember that a Tx often has a lot more power than the Rx, so it is quite possible for the communication to only be unidirectional even when you do have telemetry.
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Old Jul 19, 2012, 01:28 PM
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Joined Sep 2001
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Wow, just found this thread and how exciting!

I don't have a Devo TX, but now looks like I'll be ordering one real soon in preparation.
Sounds like an 8/8S is the way to go, at least for initial support?

Is there any way others without programming skills, like myself can help out, like in a small $ donation? PhracturedBlue ?
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