Reliable wireless data transfer

[Dennis]

Dave , your website is an excellent resource ..thank you!

Just curious about the code here.

Would you suggest specific oscillator settings ? Eg. External 4,8 or 20MHZ or would it be at all possible using the internal oscialltor?

Any particular pin choices for TX on the transmitter side and RX on the receiver side ?

Any info would be much appreciated.

Kind regards
Dennis

[dhouston]

Would you suggest specific oscillator settings ? Eg. External 4,8 or 20MHZ or would it be at all possible using the internal oscialltor?

I almost always use the internal oscillator.

Any particular pin choices for TX on the transmitter side and RX on the receiver side ?

Any pin, except for MCLR, should be OK. It really depends more on what other functions you want the PIC to handle.

Almost all the transmitters are SAW controlled so their frequency is independent of the PIC and most protocols can tolerate ±10-20 variation in pulse/space durations

[Dennis]

Dave
Thanks a million for the reply!
So if I wanted to send the value from two 8-pin dip switches I could alter the code to something like
SW1 var byte
SW2 var byte

SW1 =RF[0]
SW2 =RF[2]
Am I correct ?

And since this is a rather well established protocol there should be no need for things like holtek or motorola encoder decoder pairs ..not so ?

Is there any chance of a code snippit to add a 3rd byte of data ?

[dhouston]

So if I wanted to send the value from two 8-pin dip switches I could alter the code to something like
SW1 var byte
SW2 var byte

SW1 =RF[0]
SW2 =RF[2]
Am I correct ?

I think you want it the other way around...

RF[0]=SW1
RF[1]=~RF[0]
RF[2]=SW2
RF[3]=~RF[2]

[quote'Dennis;81044]
And since this is a rather well established protocol there should be no need for things like holtek or motorola encoder decoder pairs ..not so ?[/quote]There's no need for additional encoding.

Is there any chance of a code snippit to add a 3rd byte of data ?

'-----PIC12F629 using MPASM-----
' Sends 2 bytes + their bitwise complements using a variation of the NEC IR protocol
' repeats every 15 seconds
                     
@ __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
 
RF 	VAR	byte[6]
Copies 	VAR	byte			'RF copies 
c	VAR	byte			'loop index (RF copies)
b	VAR	byte			'loop index (RF[b])
i	VAR	byte			'bit index
wb	VAR	byte                    'work byte

        CMCON = 7	
        Copies = 4       
        'Put data in RF[0],RF[2] & RF[4] & complement in RF[1],RF[3] &RF[5]
SendRF:	RF[0]=80:RF[1]=~RF[0]:RF[2]=66:RF[3]=~RF[2]:RF[4]=33:RF[5]=~RF[4]
	Low GPIO.2
	For c=1 To Copies
	  PulsOut GPIO.2, 880           '8.8mS lead-in pulse
          PauseUs 4400                  '4.4mS space
	  For b=0 To 5
            wb=RF[b]
	    For i=0 To 7                'LSB first
	      PulsOut GPIO.2, 50        '0.5mS pulse
	      If wb.0=1 Then
	        PauseUs 1500            '1.5mS space 
	      Else
		PauseUs 500             '0.5mS space
	      EndIf 
	      wb=wb>>1
	    Next
	  Next
	  PulsOut GPIO.2, 50            '0.5mS pulse
	  Pause 40:                     '40mS GAP
	Next
	Pause 15000                     '15 SEC DELAY
	GoTo SendRF
	
	End

I would not try to go beyond 48 bits.