Help with prop-prop wireless Serial Comms

djh82uk

Hi Guys

Ive been working on this for quite a while. Basically I have 1 "master" prop board that has a numeric keypad and VGA output. Basically you type in a 3 digit number and press enter, that 3 digit is transmitted in serial via a 315MHZ TX board.

The 3 digit number relates to a relay (there can be upto 999 of them), the receiving boards ignore the 3 digit number if it is not the one that deals with that number (board one uses 001 - 030, board two uses 031 - 061 etc). It then either switches on a relay or does some pwm or whatever is required for that pin.

At the moment I have 1 transmitter board, and a receiver baord that displays the received number on a display so that I can get it woring and debug it.

Now the receiving board receives a signal but it does not correspond to what I entered. If I type 555, I get a dec value of 128, if I type 123, I get a Dec value of 128.

If I receive it as a string then I get wired characters (like greek symbols)

Now I am using the simple serial object to xmit, and the BS2_function serial function to receive, as that the only way I can get it to receive anything at all.

I am xmitting and receiving at 2400bps, im not using any resistors, just have the i/o pin connected directly to the TX/RX pin.

Any ideas?

Below is the trsnmitters I use:
http://www.coolcomponents.co.uk/catalog/product_info.php?cPath=25&products_id=186


Here is the Master (xmit) code:

Somebody said...
CON



_clkmode = xtal1 + pll16x

_xinfreq = 5_000_000





VAR



long keypressed1

long keypressed2

long keypressed3

long keypressed4

long keys

long one_ms



OBJ



text : "vga_text"

kb : "keyboard"

serial : "Simple_Serial"

'bs2 : "bs2_functions"







PUB start | i



serial.init(-1, 8, 2400)



one_ms := clkfreq / 1_000

'start the vga terminal

text.start(16)



'start the keyboard

kb.start(26, 27)

'BS2.start (2,3) ' Initialize BS2 Object timing, Rx and Tx pins for DEBUG

capture



pub capture





repeat

text.out($00)

text.str(string(" Sigmatronics.co.uk"))

text.out(13)

text.out(13)

text.str(string(" Relay Control System"))

text.out(13)

text.out(13)

text.str(string(" Enter the 3-digit number that"))

text.str(string(" corresponds to the output that"))

text.str(string(" you wish to toggle and press"))

text.str(string(" 'Enter' "))

text.out(13)

text.out(13)

text.out(13)

text.str(string(" Output Number:"))



keypressed1 := kb.getkey



case keypressed1

$df, $2a, $2b, $2d, $2e, $2f : capture

OTHER : text.out(keypressed1)



keypressed2 := kb.getkey '

case keypressed2

$df, $2a, $2b, $2d, $2e, $2f : capture

OTHER : text.out(keypressed2)



keypressed3 := kb.getkey

case keypressed3

$df, $2a, $2b, $2d, $2e, $2f : capture

OTHER : text.out(keypressed3)





keypressed4 := kb.getkey

case keypressed4

$df, $2a, $2b, $2d, $2e, $2f : capture





if keypressed4 == 13

waitcnt((500 * one_ms) + cnt)

send

else

text.out($00)



text.str(string(" Sigmatronics.co.uk"))

text.out(13)

text.out(13)

text.str(string(" You Typed Too Many Digits"))

text.out(13)

text.out(13)

text.str(string(" Try Again"))



waitcnt((1500 * one_ms) + cnt)

capture



pub send



'Activating Relay

text.out($00)

text.str(string(" Sigmatronics.co.uk"))

text.out(13)

text.out(13)

text.out($0C)

text.str(string(" Relay Control System"))

text.out(13)

text.out(13)

text.str(string(" Activating Relay:"))

text.out(keypressed1)

text.out(keypressed2)

text.out(keypressed3)

keys := keypressed1 & keypressed2 & keypressed3

'BS2.Serout_Str(8,@keys,2400,1,8)

serial.str (keys)

'serial.tx(keypressed1)

'serial.tx(",")

'serial.tx(keypressed2)

'serial.tx(",")

'serial.tx(keypressed3)

waitcnt((1500 * one_ms) + cnt)

capture







'text.str(13)

'text.str(string(" key pressed in hex:"))

'text.hex(keypressed1,3)

'text.hex(keypressed2)

'text.hex(keypressed3)

'waitcnt((1000 * one_ms) + cnt)

Here is the Slave (receive) code:

Somebody said...
CON



_clkmode = xtal1 + pll16x

_xinfreq = 5_000_000





VAR



byte rxbyte

long one_ms

Byte myString[noparse][[/noparse]50]





OBJ



text : "vga_text"

serial : "Simple_Serial"

bs2 : "bs2_functions"







PUB start | i



'serial.init(0, -1, 2400)





one_ms := clkfreq / 1_000

'start the vga terminal

text.start(16)

BS2.start (2,3) ' Initialize BS2 Object timing, Rx and Tx pins for DEBUG

capture





pub capture



rxbyte :=1



repeat

text.out($00)

text.str(string(" Waiting"))

'waitcnt((3000 * one_ms) + cnt)

'rxbyte := serial.rx

BS2.Serin_Str(0,@myString,2400,1,8)

text.out(13)

text.out(mystring)

text.out(13)

waitcnt((2000 * one_ms) + cnt)

capture

Leon

Try Manchester code. It's usually required for sending data with those simple transmitters and receivers.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

djh82uk

Hiya

How do I implement it?

Ive had a quick look, but nothing relating to usable code

DJH

Leon

You might manage without it, if you use something like the code in the AVR tutorial. He sends characters as four byte packages, which gets round the problems. It's really a fudge, though, and is very inefficient.

Leon

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Mike Huselton

This is one of the code examples extracted from the Picbasic Pro website replies:

encod_r:
For i=0 TO 7
IF mydata.0=0 Then
encoded.0[noparse][[/noparse]i*2]=0
encoded.0[noparse][[/noparse]i*2+1]=1
Else
encoded.0[noparse][[/noparse]i*2]=1
encoded.0[noparse][[/noparse]i*2+1]=0
EndIF
Next i
Return

Rec_r:
For i=0 TO 7
IF encoded.0[noparse][[/noparse]i*2]=0 Then
IF encoded.0[noparse][[/noparse]i*2+1]=1 Then
mydata.0=0
EndIF
Else
mydata.0=1
EndIF
Next
Return

I leave it up to you to convert it into Spin, which is plenty fast enough.

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JMH

Post Edited (James Michael Huselton) : 5/25/2009 4:14:14 PM GMT

djh82uk

ok, just so I understand, whats wrong with how it works right now?

I get wrong data, but it is consistently the same, so is it not just a case of bad coding on my part?

DJH

SRLM

Could you attach your code? I'm having a hard time reading your inline version.

Mike Huselton

I exaustively experimented with the transmitters that you are using 6 years ago. The only reliable way that I could get the prototypes to work is to use the Manchester code described above. The transcieving issues went away after I used the Manchester routine described. That is all I have to say: it worked for me.

The code as posted is as simple as it gets. I wrote it from memory. You need to convert the algorithm to Spin.

Incoming to the routine is mydata array containing the data to be encoded/decoded.
Outgoing from the routine is the encoded array (Manchester-encoded array) to be output.
Array element access is .o for an individual array element.

On output, the encoded array needs to be twice the size of the mydata array, since each byte of the mydata array expands to be two bytes of the encoded array.

On input, the incoming data stream of the encoded array is compressed to a single byte output of the mydata array.

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JMH

Post Edited (James Michael Huselton) : 5/25/2009 5:38:14 PM GMT

djh82uk

Hiya guys

I have added atatchments for the two spin files.

Im not upto the level of doing that manchester code

I also have a set of these, there more complicated to get working (ive not been able to do it yet) but would they make it easier?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=350185921907

Thanks

DJH

djh82uk

Hiya

Any thoughts on wether those transceivers in my last post would be better?

Thanks

DJH