RF Wireless

[Trevor]

Hey everyone.  I've been searching around the internet and I came across a neat little RF Link that may be of interest to some people here.

http://www.sparkfun.com/commerce/product_info.php?products_id=872

[bill]

very interesting, 2400bps only, but still very interesting  :)

[Goblinz]

If you look at the walkthrough there are some other versions with higher baud rates.... 4800, 200,000, and 40,000. Unfortunately the only other one available through sparkfun is the 4800 model, but part numbers are given for the others so it shouldn't be too hard to source them.

          G

[cimo]

I am not sure but i think that MIDI can t be safely transmitted/received without encapsulating it in another protocol which will take care of error checks.I mean you don t want B to played when you play A right?

Someone could say a word about this?

simone

[SLP]

I am not sure but i think that MIDI can t be safely transmitted/received without encapsulating it in another protocol which will take care of error checks.I mean you don t want B to played when you play A right?

Someone could say a word about this?

simone

I know what you mean. You're talking about a protocoll that provides "handshaking" to be sure that there won't be any data lost during transfer (Imagine an improvided synth-solo with a hanging blue note during a live show  :o)

[cimo]

it s important in these case to know how to smile whatever it is happening...

yes handshaking, no handshaking with RF afaik

[SLP]

no handshaking with RF afaik

well,.. this seems to work  ;D

We basically have to wrap the midi messages in a special protocoll, and we need 2RX and 2TX, so the 2 devices can communicate bidirectional. With a bit of coding it should work like this:

the static base sends a midi-message "XX"

the mobile part recieves the midi-message "XX", and sends it back to the base.

the base recieves the message again, compares it with the message that has been sent.

If both messages are identical, the base sends something like "ok" and continues with the next message.

If there's an error during the transmission and the mobile part recieves the midi-message "XY", it'll send it back to

the base, but the base will notice that there was an error and will repeat the message.

all in all it's pretty simple,... we just need someone who does the coding  ::)

 

[cimo]

Quote from: cimo on Today at 19:48

no handshaking with RF afaik

well,.. this seems to work  Grin

but this seems to have its own protocol as well, anyway i am up for anything coming for a future implementation of wireless midi communication, although atm the easiest thing to do is to send wireless usb with a pc host.

[dj3nk]

The newer CME Masterkeyboards are wireless. Look for CME UF60 70 or 80. Latency is <3ms.

greetz

[cimo]

any chance to sniff the code? (for educational purposes)

[seppoman]

there are quite a lot of companies offering RF modules. e.g. have a look here: http://www.lprs.co.uk/. Conrad has a great variety, too (only some of them are only suitable for some remote control stuff and not for real data transmission), as do hobby robotics shops. I think one of the easiest is the Easy Radio series from the link above.

S

[Ashiman]

the interesting thing about this is the method of transmission, if you want no jitter you want some isosynchronous -> async data transmit. this is the cause for latency IMHO.