radio rx schematic/protocol details...

[jaydag71]

hi folks, I am trying to convert some of my micros into small robots but still maintain the radio portions as well. For this I am in need of more info about the rx portion of the board and how much of the rx overall has been integrated into the rx ic? as well, I would like to know if anyone has already mapped out the signals, how they may be encoded and of course if anyone has already figured out how to process the incoming signals without the use of the stock rc-ic but rather a small pincount pic or avr perhaps.

also, on another site that describes tthe radio a bit there are also some details about the front coil drives- the chip I want to use for driving actuaters is a small integrated dual h but am left wondering how to hook up the steering coils to an h bridge as my particular microracers do not use a single coil as the site suggests this configuration does (my guess is that it uses alternating poles to achive the turning action, whereas mine uses 1 pole and 2 coils, but I haven't seen those yet). if needed I can use a single h ic and stick with driving the steering with transistors but it kind of takes away from the bonuses of an integrated option, plus already pushed for space.

any advice about the radio would be great! the steering I can figure out but always open to a suggestion. regards, jd

[KMoffett]

jd,

The 2 outputs for the steering (non-proportional) are open collector transistors (or mosfets). The Forward/Reverse is some sort of H-bridge, but it looks like there only two transistors for it. ??? These are the output voltages for the F and B terminals with respect to -V:

...FWD...NEU...REV
F 1.50v 0.80v 0.00v
R 0.00v 0.80v 1.50v

I've included a schematic of a circuit that I used to shift the RX outputs to +5v cmos logic levels for a project...if that would be any help. Ignore my pin # on the RX.

Ken

[KMoffett]

To expand on my last post:

8-output state transmitter controlled by binary logic input. (Note that inputs that include Forward and Backward or Right and Left at the same time are illegal inputs.)

8-output state transmitter controlled by 8 pushbotton switches. Only one switch is to pushed at a time.

A 1-of-8 output decoder for the receiver.

Ken

After doing a simulation on the 1-of-8 converter section I discovered some unexpexcted output states. The second schematic is corrected.

[jaydag71]

thanks for the response! yours is the best I have recieved yet,, sadly it took this long to view it cause I forgot to set the post to give an email when replied!

Thanks for the schematics! I dunno if they are going to be any use yet but I got them anyways and wll have a good look at the later.

Curious, what is the purpose of the modifications you are making?

Have you reverse eng'd the actual radio block yet? I am wonderign exactly how much of the rf block is handled by the rx1 IC? I have read that it provides a dc-dc step-up for the block but beyond that I really dunno what it does other than act as the decoder,, again, have had a hard time finding the datasheet for the parts (rx1/tx1).

For the coils, I have ended up just going with basically the same circuit as stock,, for the motor I am using a single output version of the dual dc driver. My current version has no rf at all because I have found no relyable info about the clever design,, I was thinking tp use a zigbee trx but really not enough room for such a circuit!

http://members.aol.com/rchelicam/microszr/microszr.htm << link for page that may provide some good info 4 u regarding the electronics and related.

anyways, if any good info then I will post,, as well, am looking for any trades of rc equip- am willing to do custom electronics work/manufacture in exchange for whatever cool stuff you wanna get rid of. cheers, jd

[KMoffett]

jaydag71,

The modification was out of curiosity in the recent past. Serveral years ago I was asked by the head of our Science Division to create a gag gift for our departing College President. Since his speciality was grant proposal analysis I did a "Grant Proposal Analyser", controlled by a hidden ZipZap transmitter in our Division Head's pocket. Left-output control of the receiver was a starting address in a Windbond voice recorder chip containing a dismal fog horn sound. The right-output controlled another section of recorder chip with a fanfair, and ring counter that drove flashing lights (in the bottom) and the randomly moving head on top. During the presentation each proposal he was asked to analyze ellicited the fog horn, until one of his was analiyzed and the fanfair, lights and motion indicated an acceptable grant. T'was fun.

I have a schematic on the older versions that were made of descrete transistors, but nothing on the "blobs".

Interested in hearing what you do.

Ken

[jaydag71]

yeah thats pretty cool! I've found a few similar projects a while back, including a wireless switch for routers (thought that was sort of clever).

Basically, the posted link above gives some info about the rx2/tx2 and clone IC's that you will find usefull if you don't already know the basic funct's of the IC. I also found the clone IC's datasheet a while back but it was all chinese and no block diagram of IC so basically it was useless to me. If I take the above link's info as true, the IC provides only decode as a guarentee, and possibly does a step up if a realtek IC and revC of that chip,, but as you have pointed out, most ZZ's have epoxy blob only and no indication of what you are dealing with!

To make matters more difficult for me, my ZZ;s are actually clones, most bought for parts only (but I got facinated by them the more I checked em out!) and only 1 has transmitter and it is only one that even works! On bonus side, the 1 working ZZ I have is well made in that the IC is still a blob but was placed inside a SOIC footprint so pins easily accessed and identified!

Sure, I'll try to keep you posted, hopefully I'll have some pix of my MiniQ conversion soon as I have been busy with that until I figure this whole rf stuff out!