perfect, we are waiting to order one !

On the 112 post, we see the Payalneg RC4 transponder, so why your decoder don't support RC4 ?
I have some rechargeable transponders, and they haven't the same preamble than personal transponder : valid signal don't go up.

So, the howard decoder does not support RC4 and rechargeable chips because preambles are different?

For the SPI converter problem, Have you stopped your research?

Today only 8 bits are decoded by the microprocessor, D7 to D0 are used by the decoder preamble and not by the microprocessor, is it correct ?

thanks.

somes pictures :
FPGA board (ebay at $25) ,howard loop detector and PDIA.


http://imagesia.com/2013-05-29-12-41-11-large-_8imn

the scope :
in pink : valid signal
in blue : byte ready
bus data D7 to D0
and the hex code.



http://imagesia.com/scope-3_8imo



I don't see always the same hex code, transponder always send only one message ?

These are all excellent questions!

The Cano decoder does not support the MyLaps RC4 transponders, for two reasons. First, the preamble is different. This, by itself, is not an insurmountable problem, as the circuitry could be modified to accept either preamble (or both) as valid. (Out of curiousity, I had already temporarily modified my decoder breadboard to receive just the RC4 transponder messages.) Second, and more importantly, the Cano decoder requires the transponder to send three identical messages in a row for the message to qualify as a transponder ID. The RC4 doesn’t do that; it sends a very large number of different messages, each repeating only occasionally, and none in a row. (This is an obvious way to make “cloning” very difficult.)

It would not surprise me if our very talented Payalneg has determined the data format for the RC4, which would permit him to use it with his system. Hopefully he will respond to this question.

I don’t have any access to the old AMB rechargeable transponders, so I don’t know what their transmissions look like. They are so old and rare now, that compatibility with them was not one of my design goals. Rather, I was targeting the many thousands of AMB and MRT personal transponders that exist. If the personal transponders are too difficult or expensive to obtain for your club, then you should consider using the Cano transponders.

Microchip has been unable to resolve the microprocessor’s SPI problem, so I used external components (labeled “PARALLEL INTERFACE” on the microprocessor schematic sheet) that perform the same function.

The microprocessor reads 24 bits of the transponder transmission after the 16 bit preamble. These 24 bits are brought into the microprocessor as bytes via the parallel interface.

That looks great!

The transponder can send up to about nine different messages. It sends the one which we are using for ID at least three times consecutively, then sends some type of status message on the next transmission. This means that the decoder needs to determine whether the message is for ID or status. Since we have no way of knowing what the message means, the decoder keeps a list in memory of the newest 10 messages that have been received at least 3 times consecutively. If the message matches one in this list, then it is used for ID. If there is no match, then the message is ignored.

ok thank you for your responses.
My club has rechargeable transponder and 1 AMBrc3 decoder, no problem for personnal transponder.

24 bits is it enough ?after valid signal and 3 byte report to up, you stop the tranponder message.
we are waiting now for the Payalneg answer about the RC4 protocol!
do you want the AMB transponder rechargeable preamble ?

thanks

Having the decoder receive 24 bits has been sufficient so far to avoid duplicated ID's for the transponders I have cloned, about 30 total. There may be duplications for a large sample size of transponders. There is no way to determine this for sure without knowing the transponder data format.

Thanks, but at the moment I have no interest in the preamble for the rechargeables.

ok but if you have "only" clone 24 bits of 1 message, your clone transponder clone don't work with an AMB decoder ? He works only with your cano decoder.

I clone the full length of all messages, so the Cano transponders will work with the old AMB decoders and the Cano decoder. You can read more about the transponders here:

http://www.rctech.net/forum/radio-el...er-design.html

Additionally, as mentioned in the above thread, I have created special programs that will function only with the Cano decoder, for use as "club" transponders.

Some news from me:
My transponders:

Very difficult to read ambrc3 decoder. I believe that this is due to the fact that the preamble should be 0x7916, and not 0xF916. Check it out later.
Decoder and RCM begginers:


The decoder works on castrated protocol ambrc2. Several chips sewn into memory. I now decided to change the processor on atmega32, that would be the memory chip by 93, that would not program all the time, for the sake of adding a new chip.
Mcu also has a bootloader for fast programming/

Payalneg, do you share your pcb transponder ?
RC4 transponder works with your decoder?

thanks

Only RC4 Hybrid. I will share schematics later. Decoder pcb:

Transponders pcb is clone of Howars pcb, but MC is attiny25 on 20mhz

All of the AMB and MRT transponders I have examined and cloned use F916 hex as the preamble. These function well on the 3 AMB decoders I have tried them on.

The Cano decoder ignores the first transmitted bit (D0 on the Preamble Detector / Stripper schematic), so it will accept either 7916 or F916. This was done simply because there were an insufficient number of inputs on the logic gates, and I didn’t feel that it was worth including another IC for only one more bit. Using 15 bits of the preamble gives a 1/32768 chance of getting a VALID signal on random noise (compared to 1/65536 for all 16 bits), which I felt was sufficient.

Using a CPLD or FPGA, there would be no reason not to use the full 16 bits.

I have corrected post numbers 119 and 94 to indicate 15 of 16 bits used to avoid any further confusion.

ok for the RC4 hybrid, but how you made ? have you find a preamble ?
Is it the same logic circuit than howard ?
thanks.

The hybrid sends messages in both formats to enable use with the RC3 and RC4 decoders. The preamble for the RC3 remains unchanged.

RC3 preamble, first transmitted bit on left: 1111100100010110

RC4 preamble, first transmitted bit on left: 1111110000001010

Edit: "1" indicates a carrier phase inversion.

ok thank you.
RC4 have the same preamble, but you have not find repeat bit sequence after the preamble like RC3 sequence.

There are sequences that repeat, but there are very many different sequences, and any given sequence recurs only occasionally. None repeat twice in a row.