Let's Make Robots!

How to be very happy when communicating serial wireless low tech


Since I discovered this:

http://letsmakerobots.com/node/5916 

all has changed! I was blind, but now I can see. And I can program!

On Picaxe, in order to send with these modules, use this code:

testsender:
for b0 = 0 to 255
high 3 pause 3 low 3 pause 1 serout 3,N2400, (85, 85, b0)
pause 200
next b0
goto testsender

and to recieve, use this code:

testreciever:
serin 7, N2400, (85,85), b0
sound 0, (b0,10) low 0
goto testreciever

- Of course adapted to your own setup etc.

The important parts here are:

high 3 pause  3 low 3 pause 1 serout 3,N2400, (85,85...

and

serin 7, N2400, (85,85...

Because with that combination all together, the reciever is left most happy in all states, and the result is 100% rock steady. Like in not a single bit lost in a thousand!

***

Bonus tip:

A) Hook up a speaker to your MCU

B) Send sound to it in a loop

C) Take off the speaker, and hook up the sender

D) Power up the reciever, and on the out-pin, hook up the speaker (and other wire to ground on the reciever)

Now do you hear sound from the reciever, punk? If not, you can rest assured that your recieving MCU will not get any signal either :)

Yes, you can start your own little radio station with these ;)

***

(Note that this post has changed, some of the comments below may be from earlier)

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fritsl's picture

I have only tried their serial products (Which now is completely overpriced and there is no need to use them compared to these that only cost a few dollars)

For video, have a look at their webpage: http://www.lprs.co.uk/index.php?cPath=24

Edgee's picture
You can give me some advice about video over wireless :p 
Chris the Carpenter's picture
I am playing with the same "serial over distances" issue however, I am using IR instead of RF. It seems I had the same problem of crap data coming out at the begining of a send. Badda-boom-badda-bing, I included the little "warm-up code" to my sends and damn, all is good! I am using the standard picaxe IR set-up (hardware) into a serin and (off of a 2nd chip) I am sending my info via the PWM output (set to 38,000 hz) and a standard output spitting out serout. All is simply good...     --Data in, Data out.
fritsl's picture
I am king of this, totally :D
Nicola's picture

uhm i've purchased a couple of them too (a receiver and a trasmitter). Very cheap, but time wasters and very low performances.

i heartly suggest Xbee modules :)

fritsl's picture

Time wasting or not; These are EXTREMELY cheap, and I found the challenge of making it work fun. Wasted time? Not to me, fun time :) And now I present you the way that I did it.

If you want to spend money and is more interested in steady communication, yes, I also recomend Xbee or Easy Radio!

However, understand where I came from: I was experimenting with light pulsing and magnetic field pulsing from one robot to another - trust me, that was unstable :D To me, it was / is fun to have this feeling that I now have made this vry low tech radio-link work.

If I get tired of the game, and if it get's unstable and so is obstructing the rest that I am doing, I will just insert a "boring" and expensive serial module!

GroG's picture

My God Frits,

this sounds almost, dare I say it? "Techie..."

first BOA goes Arty drawing pictures, now your getting geeky, finding all the details on how to make an under-built radio module work!

Well, more power to you .. I'm curious how it will all pan out...

Who know what's next ... Dogs and Cats living together in harmony?

Chris the Carpenter's picture

I am first wondering if one could run 2 PWM motors off of serial data. Could I hook 2 pots to ADC's on the transmitter and send something like this?

serout 0,N2400,(value1(motorA),value2(motorB))

I could set up a good loop so the receiving robot would get a constant stream of data. 

Question:

With what I am doing, noise or "init. codes" just won't work... Is there a better RF system to use? I know we are talking more money, but I gotta have a clean signal. Easy radio, maybe?

fritsl's picture

Easy radio is rock solid!

I do not see why you could not be able to send the motor-string, this is what it is all about!

GroG's picture

Cool,

I've been experimenting on serial communication between a computer and an Arduino - so that the code is on the computer - and the wireless is between computers (wifi)

The range is pretty good and apparently tcp/ip is
supposedly robust enough to work after a nuke ...

but i have not tested that part... yet :)