"Zhen Hua" Type Transmitters

[Eric Brouwer]

Ok, I know this will be a long shot in the dark. It seems that the Zhen Hua transmitters are no longer available, or are replaced by standard PPM type transmitters. but living in South Africa, has got it advantages. Old technology will be available here soon.

I noticed an increased number of requests for interfaces for transmitters that are shipped with the Dragonfly and Walkera 4 electric helicopters. As I do not know anyone with such Tx's, I was up till now unable to get my hands on one. However, I just received a Tx today, which I believe is a "Zhen Hua" type. It has the four pulses as PPM, but on closer inspection, it seems more like a PCM or serial signal, than PPM.

Is there anyone willing to give me a hand with the code for a PIC serial interface, or even just a full description of how the signal works, an how it should be decoded with a PIC? I am not realy in the mood to spend hours to try and figure it out. Any help would be GREATLY appreciated.

Thanks

[Malc C]

Eric,

Try contacting John at www.rc-electronics.co.uk as they were one of the first to bring out an FMS interface for this protocol. I'm sure he will be able to give you some insite, but doubt if he'll get involved in the code writing as you are in effect a "competitor".

[Dalite]

Ok, I know this will be a long shot in the dark. It seems that the Zhen Hua transmitters are no longer available, or are replaced by standard PPM type transmitters. but living in South Africa, has got it advantages. Old technology will be available here soon.

I noticed an increased number of requests for interfaces for transmitters that are shipped with the Dragonfly and Walkera 4 electric helicopters. As I do not know anyone with such Tx's, I was up till now unable to get my hands on one. However, I just received a Tx today, which I believe is a "Zhen Hua" type. It has the four pulses as PPM, but on closer inspection, it seems more like a PCM or serial signal, than PPM.

Is there anyone willing to give me a hand with the code for a PIC serial interface, or even just a full description of how the signal works, an how it should be decoded with a PIC? I am not realy in the mood to spend hours to try and figure it out. Any help would be GREATLY appreciated.

Thanks

Also, if you look at the silkscreening of the main board in the transmitter, you may find that it has places for channel 5 and 6. Channel 5 is a toggle for Mode II to Mode I and Channel 6 is PCM/PPM switch. A SPST Switch (for each ) is all that is required to activate these circuits.

This info is from an ESky Schematic for their 4 Channel TX which is apparently made by FEDA.

It is likely that other knock-offs are copied from the same design as this knock-off.

In the early days of IBM PCs, the original 8088 BIOS had a mistake that reversed video attributes on an exit from Lotus software. The flawed BIOS was copied by so many knock-off manufactirers, that it was not until Lotus software eventually fell from the mainstream that the problem disappeared. I see a trend here....

[CoolWombat]

I've just got my Walkera 4CH as well. They have redesigned the PCB and removed all the tracks that will allow you to add the 'missing' components to add back the 5th and 6th channels. The two toggle switches and push button (top right) in the front are all dummies and are not connected internally.

I did managed to get it to work FMS using a homemade cable. I used the info provided by Dalite in a previous post, but with a slight variation - pin 3 is left unconnected. So Eric, you won't need to do up a PIC serial cable if you have the same transmitter as me.

[Eric Brouwer]

@ Dalite
Thanks for the info, will have a look.

@ CoolWombat
Looking at the number or queries/complaints regarding the supplied Dragonfly cables, I do think it's woth the effort to get the tx running on an interface. As I already sell serial and USB joystick interfaces, I plan to incorporate the Zhen Hua protocol in my existing interfaces at no additional costs. I do not want my clients to battle for hours downloading/installing drivers to try and get it running (if they are lucky).

[bluesky123]

Eric,
The problem is not that available serial/USB interfaces are lacking Zhen Hua support, but the fact that some ignorent/shady vendors are selling old (Zhen Hua compatible) interfaces saying that they would work with new Walkera or ESky transmitters (which are not Zhen Hua compatible)...

Therefore, adding Zhen Hua support to existing serial/USB interfaces will be a futile excersize--there are few Zhen Hua compatible transmitters on the market, which could take advantage of this.

Boris

[Eric Brouwer]

@bluesky123

Can you tell me what is the difference between the Zhen Hua and Walkera transmitters? I thought it was the same. The two tx's I got hold of, was shipped with a Walkera 4 and a Dragonfly heli. Both are the same, and outputs a 5 byte datastream at 19200 buad. It seems both of them was shipped with dummy cables.

The converting of Zhen Hua to FMS was quick to do, and I have incorporated it into my standard 12F675 serial interfaces, which when done, will auto-select between PPM & Zhen Hua. However, if the Zhen Hua is different to Walkera, I would like to address the Walkera as well.

As I see an increase in the amount of customers having purchased these "combo" packages, I want to ensure that I can help them with an interface that works.

The other option is, well, bad luck, you bought it, you figure it out...