rotarypower3

I have tried to get my Walkera TX to work with 2 different receivers (gws and align) with no real success. I have read elsewhere of people having no luck with using any other tx with the walkera rx either, apparently it uses it's own style of PPM/PCM.....

bluesky123

My Feedback: (2)

rotarypower3,

Probably, you are having Xtal compatibility problems. I've tested several of my Walkera transmitters (from unbelievably crappy 4ch heli to just simply crappy 6ch transmitters from 22A, 22E, and 35 models) and they all worked with my receivers just fine. I tested them with an old Hitec 3500, Sky & Technology CRX-M7 DSP receiver, and a small Hitec single conversion 5ch RX--all worked fine.

All Walkera transmitters I've seen use the standard PPM signal, it just has a bit longer frame duration (ot shorter pauses between channel pulses?) than the other radios. A bit like Futaba radios of early 90s...

Boris
www.milehighwings.com

rotarypower3

You're probably right about the xtals Boris.
Both the rx's are 36mhz, the walkera tx is 35mhz.... I tried 2 sets of the 35mhz xtals and two sets of 36mhz... all I ended up with was constant glitching.....[] Oh well doesn't matter anymore as I bought a REAL radio and will just use both the walkera tx's I've got for FMS...

Heliboy71

thats all fine, but its not the radio i care about as for the radio gear, i could use it prop up my garage heli bench ! its that useful to me - I wanted to use my HITEC eclipse 7 radio with the WALKERA Receiver / spd / gyro , and thats where the prpblem starts...

anyway, becuause of all the added frustration and getting no where - i put an old e-sky combined speedy and gyro unit with a 35 mhz receiver i found lying around the garage into the front box of the walkera and it works fine..

im just suprised that its that hard to get a 35 mhz receiver from china to work with a professional radio?

go figure.

oops

The Walkera stuff is almost common in it's formats. Except there are extra channels used by the TX to send control information to the RX... Without the correct coded signal, the RC won't work - it's a safety feature. You could probably crack it- but it's not worth it.

Just replace the Walkera stuff.

Anwyay. I have been able to use my Walkera 4ch with a Futaba receiver just fine. And you can also change the 35 MHz to 36MHz with just a crystal change.

David

chris6414

My Feedback: (10)

I have a new twist on all of this. Anyone find compatible crystals other than the ones that come with the walkeras, that will work. Mine are type 72-4s and I tried other FM crystals from my Futaba set but they wouldn't work. Will Futaba FM crystals work in Walkera radio gear? and if not why won't they? Wrong type? Could I have the wrong band for the receiver?

I believe my crystal (s) are bad and of course don't have any walkeras to test it. I understand why the radio gear is not compatible, but why the crystals?? [sm=confused.gif]

franky888

Does anyone know how to play Reflex XTR without USB connector? the transmitter is connected to the PC through sound card line input using cable, some say it can be done with a few modification in the reflex xtr file configuration setting.
Is this as simple as replacing the input section in file configuration setting with sound card address? which is the default is seeking an USB address, so when the program is launch, it's should directly search to sound card line input address, looking for a controller, coz I've heard someone has already success doing this, due to all of his computer USB ports are broken... this is similar as FMS default connector. Does anyone know or have heard before about this?

e1000

hello! anybodie out there? this thread is a bit old, but i hope someone reads it....
im a somewhat skilled electronic engineer, and love RC. Ive recently bought a Walkera #4 receiver, just for the fun of it, and im still trying to make it work. everything ive read here seems to make sense... but still theres something missing. if theres anyone out there who can post an oscillogram of a walkera transmitter, so i can decipher it, it would be great. Ive programmed a pic and an HC08 to emulate an 8 channel PPM signal, but still nothing... anyone has a walkera transmitter, an oscilloscope and 2 seconds time? ill be grateful! and i promise to post everything i find out. thanks!

vega2614

Has anyone tried using the 4-channel PPM E-Sky Lama V3 transmitter with the Honey Bee King/Cool 6-channel PPM receiver? I want to save money by using my Lama transmitter for a plane, so I want to get a compatible receiver. EK2-0420 seems compatible, but I'm not sure. Thanks.

Dzl

Hi,

Just got a trashed Dragonfly 4. Repaired mechanics but had no TX. I borrowed a matching TX and hooked it up to a oscilloscope. It uses a regular PPM frame with Throttle at ch3, tail at 1, elevator at 2 and aileron at 4. Channel 5 thru 9 must be at -100% or the RX won't start.

One catch!

The whole PPM frame is compressed in respect to standard timing.

Solution:

Crack open the RX. Replace the 4MHz resonator (for the built in microcontroller) with a standard 3.2768MHz crystal. Now the RX is compatible with any standard TX, which can assign these channels and put CH5-9 at -100%. I uas a Multiplex EVO9

While you have the RX open replace the crappy 5V regulator with one that will drive both servos simultainously

e1000

Hello!! yes, i`ve evolved since i posted this!!! The receiver needs 9 active channels to initialize, and then it just uses the first 4 and drop the rest. Ive still have not find out if channels 5-9 have any influence on GYRO-MIX-or whatever. Im currently developing a transmitter based on an old hacked JR F400, and a programmed ATMEL ATMEGA8 to do the whole processing (AD, PPM, etc). If youre interested, ill post some results (whenever i have them!)

Dzl

I have tried to fiddle with chan 5-9. It seem that their only purpose is safety. The speed controllers shut down if any of these channels are above -25%.
I think rather than coding a whole new transmitter just do the hack and use a regular TX. Or perhaps a add-on like we did for X-Twins

http://webx.dk/rc/xtwin/xtwin.htm

GTX SlotCar

The DF4 Tx uses the Zhen Hua 5 byte protocol. This isn't used much by anything anymore. Outside of (maybe) an old Futaba Tx, your DF4 receiver will only work on it's own Tx.
I believe the DF4 Tx will work with some other Walkera Rx's, but the DF4 Rx only works with it's own Tx. Hacking the Rx may be the solution.

e1000

ive read a lot about this zhen hua, im still not convinced. The walkera #4 RX is just a normal negative modulation (that is, NRZ) PPM with 350uS mark timing and 300uS (non standard) - 1600uS space timing. besides the slight non standard timing, its a normal straightforward PPM. Perhaps some new Tx and Rx uses Zhen Hua, i wouldnt know, ive not laid my hands on those yet ( ). Ive a homemade TX with ATMEGA, and it works fine. However, its very interesting, , ive not tried that one yet. Good one. Any electronic-hacking lover out there wants to join?

GTX SlotCar

I think it's old, not new. Some people with old Futaba radios that used Zhen Hua have said they do work with the DF4 RX. I have not tried it myself, only repeating what I've heard. Many of us have believed this to be true for the past 3 or 4 years. It'll be interesting if we find out that it's not.

e1000

aha, so perhaps its older and the plain PPM are newer. if anyone has any of this zhen hua TX it would be nice to have an oscillogram posted, maybe we can draw some conclusion.
By the way, ive foud this very very interesting paper on the net,
http://www.smartpropoplus.com/Docs/W...k-0701_PCM.pdf
very interesting, it explain with high level detail how the PCM on walkera WK-0701 works.
Once i have finished this nasty cheap and dirty transmitter im working on i`ll post photos, and we`ll discuss it.

huguesdb

Since there are some pretty clever folks participating in this thread, I have a question concerning the Esky 4 in 1. I'm looking to capture the motor control signals AFTER the gyro mixing but BEFORE the brush motor ESC.
Has anyone tried to identify where on the circuit this could be and is it the normal 1 to 2 ms pulse I could perhaps use as an input to a larger ESC or a brushless ESC?

Any help would be appreciated.. I am not equiped with scopes.


Hugues

e1000

im sorry, the only signal you can get is a PWM of around 2 khz, wich comes out of one pin and feeds the mosfet strightaway. It doesnt have even a resistance. The mixing, gyro and ESC functions are internal, in the uP. What you can do is take this signal, and put it on a larger MOSFET. But why would you want to feed a brushless ESC?

huguesdb

Thanks e1000.. surely the pwm 2kHz signal would be ok to drive a brushless ESC ?
Yes, I know the mixing is internal but all I want is the RESULT of the mixing to put into a brushless esc.. why do i want that ? well, to put 2 brushless motors in the lama.

Currently I have a Lama with 2 brushless, 2 ESC, a gyro and a 6 channel receiver. This thing is dynamite! but is quite expensive. If I coule drive the brushless ESC directly, the upgrade would be much cheaper.
Also, I have noticed the power stage is not terribly efficient - I get LOTS more power from my standard engines, or the Xtreme engines, when I use separate brushed motor ESC. Also allows you to run on 11.1 V LiPos.

Any ideas?


Hugues

e1000

ahh, ok! i get the idea. the thing is, its completely different a dual-main rotor heli compared with a "normal" heli. I dont have any of them, but, from what ive read, there are several important differences, for example:
both rotors are used in lifting the heli. so, both must work in conjuntion to provide the lifting force. the gyro signal is used to make one rotor spindle faster than the other, so the resulting "total rotating quantity"(1) compensates some outer force or makes the heli turn. in order to do that and not cause the heli to drop as a stone, both rotors are mixed in such a way that when one goes slower, the other rotates faster, the total rotating quantity changes but the lifting remains "more or less" the same. In a normal heli, however, the gyro never mixes into the main rotor, so I dont think it will work properly, much unstability and stuff. But.... i take note of your project. Its very interesting, i would like to know what ideas you have and what youve done. We could even do some microcontroller programming and try to make the thing work properly.

im sorry... its not like that. this PWM is a signal that ranges from 0% to 100% duty cicle according on the gyro and stick signal, and cant be fed into an ESC, normaly ESCs only accept standard PPM signal... and they are very very different.

(1) sorry for that. im almost an engineer, and i have a very strong phisics formation. however, i have studied everithing in Spanish (my mother language) and i dont know if thats the correct expression in english. also, i apologise for my grammar mistakes... :S :S

huguesdb

Hola e1000,
It is no problem - I understand your english very well and yes, u get the idea / problem.

Here is the state of my project: I used the E-sky Lama frame and aluminium cnc moving parts with an Xtreme canopy, landing skids and tail. It does not look like a lama any more but never mind! Photo 1 shows the general view, photo 2 a closeup.

With just a little adjustement, I put in 2 18mm diameter brushless motors. I also have some 12mm ones to try but dont have the pinions yet.
On the side of the heli, I put 2 10A brushless ESC.
Inside the canopy, other that too many wires, I have a 3.5g Spektrum 2.4GHz receiver and an Esky 0704 gyro. The gyro is between the receiver and one of the motor ESCs.

So yes, in principle, when there is a correction on the gyro, the lift changes. So far, this has not been too bad, but I have not had strong winds to correct. I tried a V-tail mixer to distribute the correction to both motors but did not get satisfactory results. I also tried, for fun, to put 2 gyros for the horizontal correction and it does work! One of my fun versions had 4 gyros - one acting on each motor and one on each servo, so the yaw, pitch and roll were stabilised! Very nice to fly! And, the lift is over 600g, which is awesome. I made some aluminium blades to be able to handle the power. This think is looking mighty:

All this is fine for playing but the cost becomes prohibitive. So my idea was to use the original E-sky lama 4-in-1 which does the gyro / mixing. I have seen one little device that uses the signal used to drive the brushed motor, converts it to a PPM, then this can be used to drive the ESC for the brushless. However, this adds 60$ to the heli, which is more than the receiver and gyro (well, not the spektrum receiver).

The photo 3 shows the E-sky board: power is supplied through the power lead, the two double pins on the right are to power the brushed motors.
On the right as well you have the 2 power stages, as well as the elevator and aileron PPM inputs that come from the receiver (which is a separate board).
The two little chips in the middle are pobably to drive the mosFETs (one of which is burnt on this photo) and on the left is the gyro chip and a an unknown chip. On the other side of the circuit is the xtal, microcontroller, 2 pots to adjust parameters and the stabilised power supply.

If I were designing this circuit, I would use standard modules - for the channel / gyro mixing - giving me a PPM output which I would then feed to the circuit which controls the brushed motor.
This is what prompted my question : is there the mixed PPM signal coming out of the microcontroller ?

With a separate microcontroller, the first thing would be to a type of V-tail mixing - sending the correction in positive to one motor and negative to the other, so that we maintain the lift. I'm not sure if we would need to take into account that it may be faster to slow down the rotor than speed it up.
However, if we go into this direction, then I have some definite ideas (I think they are good!) for providing additional flight stability and manoeuverability! Are u interested? I am a software engineer, although not much experience with on-board stuff, but willing to learn.

Alternatively, if u care, I could send u the 4-in-1 to see if we can get a signal.



Hugues

e1000

noooo, dont send it! It would be a lot of money, just to send from switzerland over here a small PCB. We can do some otrer things instead. Do you know some electronics? A little bit? You can use your computer and turn it into a cheap oscilloscope. Of course, you have to make you own probes, and you must be very careful or your PC will blow away... ok, not blow away, but theres a pretty good chance you will never hear an MP3 again. Anyway, here,
[link=http://www.aubraux.com/dsp/index.php#download]DspSee[/link] youll find the program. It uses your soundcard to acquire signals and present them "like" an osc,
its NOT like having a real Oscilloscope, but useful enough for sampling PPM, PCM and RC signals. If youre interested, i can help you with the probes and stuff.

I dont get why it didnt work well.... i mean, at least in theory it sounds great. Perhaps the mixing percentiles? Or the gyro gain? There are a lot of variables to play with... we could try a programmed mixer, wich microcontrollers are more common where you live? PIC? AVR? I mean... wich would be the easiest for you to program? so i send some C source, and you program and try.

Formidable!!! its so simple i had not think about it before... i have to try that on my heli.... big $$$, but its worth to try.


Yes, perhaps that wuld be the easier way, but not the cheapest (important), nor the most straightforward. If you have a microcontroller, you can do a lot of stuff "inside", in a discrete, precise, fast way, and the you transform and output the result the way you want (namely, PPM, PWM, led blinking, etc.)... i dont think youll find a PPM wiht the mixing result.

Of course im interested! Im almost an electronic engineer (hope to become a solid engineer on March next year), and also willing to learn so we can do some stuff. Ive just finished hacking a walkera RX601 receiver to work with a walkera #4, i send photos...once ive learnt how, and i think it will be flying soon.

e1000

i forgot,
send me 2 photos of the best definition you can get, or send me the numbers on every chip, the "unknown" chip must be an LM324, or some quad amplifier, used as a data slicer, ampli for the gyro, etc.... ok, with the number well discuss more accurate

huguesdb

There are 2 boards on the 4-in-1 - the receiver with xtal, antenna, a couple of small ICs and 4 channels for servos. The elevator and roll channels go to the 2 servos on the swashplate. The power and rudder channels are sent as PPM signal (I have put servos to test) to the second circuit.

The second circuit side 1 is the photo here.

CJT1117 is a voltage regulator - 1A, presumably to drive the servos and board.
http://www.alldatasheet.co.kr/datash...T1117-3.3.html

There is what looks like the xTal, with 4000 on it.. my guess is its 4MHz

The ELAN microcontroller is documented here.. nothing special about it.

http://www.emc.com.tw/eng/8bit_prod_...rcial+Grade%29

On left are 2 connectors for the motors. On bottom is a red/green diode and 3 pots. I dont know what the last one does.. its notmally not visible.

Second photo: other sideof board 2

SS24 look like 2A schotthy barrier.. something like this http://www.fairchildsemi.com/pf/SS/SS24.html
It burnt when I put the power the wrong way round! I must have been tired!

The IR F7413 are power mosfets to drive the motors. http://www.irf.com/product-info/data...ta/irf7413.pdf

As you guessed, the unknown circuit is a ST microelectronics 324 but tough to find the exact specs.
http://www.st.com/stonline/stappl/pr...ber&search=324

The last one is a bit of a mystery - its in a metal casing, seems to have only 4 pins and appears to be a Schottky Barrier Diode -
http://www.datasheetarchive.com/sear...ma715&manystr=
Anyway, thats all i find about it.

This leaves me guessing as to where the gyro is..


Hugues

huguesdb

Thanks, I am looking at that software.. have installed but its bugging... Do my probes go to the mic input ? Yes, help with probes is great!


Yes, i did like the idea.. maybe i try again.

I have some stuff for PICs, including the dsPIC 28 pin demo board and the Explorer 16 dev board with the ICD. I did play around but have not done anything serious. Am happy to learn!


Just make sure u leave enough time for studying!
Now, lets see.. a rx601 is made for the CCPM helis - i have one on my DF52 - which is 120° swashplate - and the DF#4 is 90°. Yes, put some photos..

ok, late here.. sleep time!

Hugues