Using Linx RF modules ?

[Sam]

I've searched but haven't found the answer. I have Linx TX and Linx RX modules from Rentron as seen HERE and HERE.

My question (problem) is that I can send to and from a 12F675 through Hyperterminal just fine. But when I connect the output of the PIC to the DATA in on the TX module and I connect the DATA out from the RX module to the serial in line going to Hyperterminal, all I am getting from the receiver is garbled characters, mostly boxes almost non-stop showing in Hyperterminal.

I do notice different characters when the PIC and Linx are actually transmitting and the TX is definitely working as I have a field strength meter next to it. I am using N2400.

So to sum it up, how do I get the receiver to receive the DATA and display in Hyperterminal ?

Thanks for any guidance with this !

Sam

[mackrackit]

Can we see you code so we can tell you where the problem is?
Did you code for the data slicer?

http://www.picbasic.co.uk/forum/showthread.php?t=11589

In the meantime look at the tips and tricks section here.
http://davehouston.net/

[Sam]

Can we see you code so we can tell you where the problem is?
Did you code for the data slicer?

http://www.picbasic.co.uk/forum/showthread.php?t=11589

In the meantime look at the tips and tricks section here.
http://davehouston.net/

I will post the code, it's on another laptop I'll fire back up in a little while and post from there. Not much code to it though, just a simple routine to test and be a starting point to learn.

Did I code for the data slicer ? Uh, no, I've made data slicers before from TL 085 op amps before but I don't know about coding for them. I did notice in the data sheet that the RX module has a slicer.

Thanks for the links, not to get OT but I really like your site and bookmarked it ! I packed my last home with X10 stuff, touchscreens controlling TV's and whole house audio through a Smartlinc controller with IR ports, the Smart rocker switches with the vertical row of green LED's, and on and on. I miss that setup, I just have some basic X10 control here now, I still have the controller though.

One more OT thing I thought you might be interested in, I also have the X10 remote pan and tilt modules and the range on the handheld remotes were awful, I added a variable cap in series with a telescoping antenna installed in the remote and the range more than quadrupled and they look factory. They were almost totally useless to me before I added the antennas.

I'll go back to reading your links on this topic though and post back later.THANKS again.

Hi Joe, I think I did try T2400 and still garbled, I'll check it again. BTW: your tachometer program is working great for me, only problem is once you go over ~1000 RPM I have to divide the readout by half but that's not a problem since I don't need to run the machine over 1000 RPM anyway. I checked it with a handheld laser tach.

Man, I keep getting off my own topic here,

Thanks guys, later.

[Sam]

Okay, I did have some success. I had both modules on the same breadboard, I moved the TX module to it's own breadboard and instantly started receiving text properly on the RX module and feeding the data out of the RX into hyperterminal.

This was without an antenna on the RX module, with the antenna I'm getting all sorts of characters which must be "static" of course. So I guess that I need to have a PIC connected to the data out of the RX and programmed to only respond to the string my TX is sending right ?

Such as: Serin DATAIN_pin,N2400,["THIS IS A TEST"] ???

Here's my extremely simple "code" ...

'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2009 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 8/16/2009                                         *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
'12F675
_CONFIG
@ DEVICE PIC12F675, XT_OSC 
_NOCLKOUT  
_WDT_ON 
_PWRTE_ON
_MCLRE_OFF
_BODEN_ON
DEFINE OSC 4
INCLUDE "modedefs.bas"
TX_Pin VAR GPIO.1    'To DB9 TX pin 3
RX_Pin VAR GPIO.0    'To DB9 RX pin 2

TRISIO.0 = 1         'Set GPIO.0 to input.
TRISIO.1 = 0         'Set GPIO.1 to output     

ANSEL = 0            'disable ADCs
CMCON = 7            'disable comparator


Tx_Pin = 0           'inverted mode idle state


Pause 100            'OSC settle time... 

loop:
    IF GPIO.2=1 THEN
	SerOut tx_pin,N2400,["THIS IS A TEST",13,10]
	Pause 500
	ELSE 
    GOTO LOOP
	ENDIF
    Pause 500
    GoTo loop

[dhouston]

with the antenna I'm getting all sorts of characters which must be "static" of course. So I guess that I need to have a PIC connected to the data out of the RX and programmed to only respond to the string my TX is sending right ?

Here's a picture to illustrate the problem.

The data out line of a receiver (i.e. output of the data-slicer) is shown in the bottom trace - the analog input to the data-slicer is shown in the top trace. All of the RS232 methods (HserIn, HserIn2, SerIn, SerIn2) wait for a start bit and then sample at the midpoint of each bit period. They will interpret the random noise on the left as data bytes - the output will be a series of random bytes.

From the datasheet for your receiver

• The receiver’s output may appear to switch randomly in the absence of a transmitter. This is a result of the receiver sensitivity being below the noise floor of the board. This noise can be handled in software by implementing a noise-tolerant protocol...

What is the data you want to send? How long are the messages?

[Sam]

What is the data you want to send? How long are the messages?

My first thought was as follows, a PIC and TX module located at a CNC machine,
when the machine moves to specified locations a button closure would activate the PIC/TX to send a short message such as "Change Tool". And other sensors could initiate messages such as "motor stopped" or "coolant flow", ETC.,ETC. and this would be received and the message displayed on an LCD through a PIC on the receiver end.


Or, maybe the better way is to have the PIC/TX send a single character such "a" 5 times or so for one button and another like "b" to the RX/PIC and the RX PIC will generate the appropriate sentence to be displayed on the LCD.

So to answer your question, just short messages or single characters representing different button closures.

[dhouston]

I also have the X10 remote pan and tilt modules and the range on the handheld remotes were awful, I added a variable cap in series with a telescoping antenna installed in the remote and the range more than quadrupled and they look factory. They were almost totally useless to me before I added the antennas.

The FCC frowns on that. You should not alter the antenna (or anything else) on a transmitter. You can usually achieve the same result by improving the receiver antenna or by adding a wideband preamp between the antenna and receiver. This will improve range without interfering with any hams in the neighborhood.

[Archangel]

I do notice different characters when the PIC and Linx are actually transmitting and the TX is definitely working as I have a field strength meter next to it. I am using N2400.

Did you try T2400 ?