EZ-Tec R/C models control data format

[Pigeon]

Posted in P&P for maximum readership for a fairly obscure question.

I have an EZ-Tec Scientific Toys radio controlled car but not the transmitter for it (it's a new Mini with RWD and generates the sound of a V8...) I also have a radio control transmitter on the correct frequency but using a different control protocol.

The car seems to expect a digital signal using what I would imagine is a serial data format as used by remote controls for TVs etc. of which there are many different although similar varieties.

To get the car working is basically a matter of programming a PIC to generate the correct format serial signal and wiring it into the transmitter - but I don't know what format it is.

If anyone happens to know what the bit timings are and what start and stop bits are used etc. it would make it much easier to get the thing going.

TIA...

[Davi]

Presume you've asked on RCgroups.com? lots of people that play with this sort of thing over there.

[Neil_H]

Just crack it open and swap the receiver with one that's compatible with the transmitter, much easier.

[Pigeon]

Can't do that. The decoding of the signal, the generation of the control outputs and the synthesising of the sound effects are all handled by the same chip - which is of the unhelpful custom-chip-mounted-naked-under-a-blob-of-epoxy variety. I could find another way to get the control functions working easily enough but the sound effects wouldn't work, it would at best remain on tickover all the time. I need to replicate the original control data stream to get the original processor to do its stuff.

[polus]

Haystack... needle.... If you knew the data the timings would be easy to crack with an arbitrary waveform generator but not knowing the data... erm good luck.

[Pigeon]

And if I knew the timings then I wouldn't have too much of a problem figuring out what the data needs to be it's trying to crack both at once that makes it awkward...

[polus]

You could brute force it?

[Pigeon]

Worst comes to the worst that's what I shall do

[The Excession]

Pigeon said:

Worst comes to the worst that's what I shall do

Gosh... I wish I had so much time available....

[Pigeon]

It would be more CPU time than my own

[Pigeon]

...meanwhile my topic on rcgroups.com has attracted no replies whatsoever

[The Excession]

Pigeon said:

...no replies whatsoever

Can't you just get something like this and hack it from there?

If you need stuff buying in the US my sister lives in Washington, and she'll gladly purchase and 'gift' it over to you so no import duty. Still, what's the import duty on a $6 dollar toy?

(Haven't mamanged to find much else on EZ-Tec stuff on the net, so I appreciate your frustererations)

[Pigeon]

They are so ridiculously cheap that that is probably what I will end up doing... I have found one model for only a tenner in the UK. It does somewhat ping my sense of inelegance to buy a whole 'nother model to get the first one working, but then I do have three little nieces to pass it on to

[Davi]

Pigeon said:

...meanwhile my topic on rcgroups.com has attracted no replies whatsoever

Blimey, that's a surprise. I'll ask around a few of my old RC mates, see if anyone can come up with anything for you.

[mybrainhurts]

Can't you just go...

Vrooom, vrooom, burble, vroom...?

[Pigeon]

Davi said:

Pigeon said:

...meanwhile my topic on rcgroups.com has attracted no replies whatsoever

Blimey, that's a surprise. I'll ask around a few of my old RC mates, see if anyone can come up with anything for you.

(post is here)

[vdubbin]

Pigeon, after a quick look at the EZ tec stuff, I doubt it's a digital Tx Rx system, far more likely to be a case of using AM when the Rx is FM or vice versa. Also, even if you've matched the frequency (27Mhz, 49Mhz etc) there are still a buch of channels within that freq band that the sytem could be using.
Does the car have proportional steering/throttle or is it a simple forwards/back/Left/Right setup?