HT-12E with AVR problem. I really need help.

Why are you so hung up on using the HT-12D/E pair? Is it just that they are the first things you came across or are you *really* stuck with using them/ It seems to me they are making your life unnecessarily complicated. There are better modules around for your task, as has been pointed out before.

Ken

Thank you ken.

Could you please sugguest me some "better modules" for transmitting three message at the same time.

It is because HT-12E is 1 to 1 encoder and seem it is design to send more than one message at the same time.

I really get stuck on HT-12E, but it is what my partner wants.

Thank you for your time.

You need to define yourself a simple protocol. For example,

Send the message 4 bits at a time, then use a software shit register to reassemble the message. If the crc is wrong, discard the message. If the message needs to be sent reliably, then you need some kind of acknowledgement mechanism in your protocol, so a failed message can be resent.

i answered this a few weeks ago. you have 10 bits to send

abcdefghjk send 1abc then defg then 0hjk then re-read your 10 bits and repeat.... when receiving

you'll get anonymous 4 bit symbols wait till you get one starting with 0 then wait for one starting with 1 that's guaranteed to be an example of the first symbol. and contains bits abc the next contains cdef and finally 0hjk Bye. Jasen

Thank Jasen.

Could you please explain some more detail about that method.

For example, 10 bits is "abcd efgh ij"

I send the first 4 bits as

"1abc" with 1 to tell reciever it is the start four bit

then

"defg"

then

"0hij " with 0 to tell reciever it is last four bit

repeat it to get other 10 bits

Am I on the right track?

Comms 101. Always use error checking. An 8 bit crc adds virtually no overhead, but provides increased reliability.

yes, that was the plan... others mentioned error checking, and if errors in the data will be a critical problem it's prtobably worth looking at going that way it they'll only be an inconvenience my way man be easier,

it's the change from 0 to 1 that indicates the first symbol (1 and three bits) the middle symbol could have either 1 or 0 in that place but never immmediately after 0xxx symbol so can't be confusd ....)

personally I'd be looking for a way to connect the AVR's serial port directly to the transmitter and leave the encder out entirely.

Thank Jasen

"personally I'd be looking for a way to connect the AVR's serial port directly to the transmitter and leave the encder out entirely."

Do you mean do the software encoding by AVR chip and output that encoded data by serial port and connect to transmitter directly?

Thanks Andy.

What is meaning of "Comms 101"?

cheers

It means this is the very basics, ie, the first subject you learn at shcool.

It usually means you need to go read a book.

I mean just writing the bytes to the serial port asif the sending chip's transmit pin was attached to the receiving chips receive pin.

You could put a preamble in there (say two bytes for address data to help with rejecting other transmssions on the same frequency (eg door openers etc))

Then at the receiver watch for the two bytes and store the data the data

Andy reccomends checksumming it, which is probably not a bad idea. for data this short it's as easy to invert the bits and tack it onto the end

when you receive exclusive-or the good and inverted data together and if you don't get all bits set there's been an error.... so ignore that packet and wait for the next.

Bye. Jasen

I normally ignore typos, but "Shcool" is just too funny in the context of your message. ;-)

One day i will use a spell checker!

When i try to compile code i often have to spend several hours removing typos. MS make it easy these days with there 'intellisense', i just need to find a decent newsreader that has the built in autosmarts.

I still use Netscape 4.78 to read newsgroups. it has a decent spell checker, and if it doesn't recognize a word you can copy and paste it into Google. If you get a "Do you mean" with an alternate spelling and its right you can copy that back to your message. Run the spell checker again and click on "Learn" so it will remember it for the next time.

Agent has a spell checker too, it just means I have to click the 'ABC' button up the top. Word is smarter, it does the spell check for me and underlines it in red. Perhaps i should give the new outlook 2003 newsreader a go, that is if 2003 has a newsreader built in.

and find a decent grammar checker as well. "there 'intellisense'," should be "their 'intellisense'," or, maybe, that package will do both! No, "there" is the correct spelling of a word, so probably will not raise an error flag. Oh, well!

Daniel