RF Transmitter/Reciver

[Luciano]

Hi,

Can you post the results of the RSSI test?

http://www.picbasic.co.uk/forum/show...8&postcount=38

If you do so we will know if somebody else is transmitting on the same frequency.

Best regards,

Luciano

[Fredrick]

Step 1: Connect a digital voltmeter to the RSSI PIN of the receiver.
(Make sure the multimeter is set to DC volt and that you measure from the RSSI PIN to GND).
Power on the receiver and make sure the transmitter is powered off.
Q1: What voltage do you get on the RSSI PIN of the receiver?

A1: 1,22V

Step 2: Power on the transmitter.
Q2: What voltage do you get on the RSSI PIN of the receiver?
(The transmitter and the Receiver are powered on).

A2: 1,22V

Step 3: Connect +5V via a 1k ohm series resistor to the DATA pin of the transmitter.
(The transmitter and the receiver are powered on).
Q3: What voltage do you get on the RSSI PIN of the receiver?

A3: 1,77V

Step 4: Connect GND via a 1k ohm series resistor to the DATA pin of the transmitter.
(The transmitter and the receiver are powered on).
Q4: What voltage do you get on the RSSI PIN of the receiver?

A3: 1,22

[dhouston]

If you do so we will know if somebody else is transmitting on the same frequency.

Everyone in Europe is transmitting on that frequency. It's the only one allowed for this type of use. There are restrictions on how often & how long you can transmit because so many share the frequency. Allowing 25mW when everyone uses the same band is sure to lead to problems.

An RSSI output, in and of itself, may be of little help as noise can generate a high RSSI - it depends on the details of both the circuit and the methodology - it's not equivalent to CD on FSK. With the RWS superregenerative receivers, I measure the modulation depth (difference between the pulse and following space) of the lead-in pulse which has proven to be a good proxy for signal strength.

Recording or viewing the data output line is the best way to determine whether it's random noise or a signal (or signals) from the transmitter (or other transmitters). It's easy to do by recording with a soundcard and viewing it in a soundfile editor or with soundcard oscilloscope software (Google Virtins) or even the Parallax USB oscilloscope. The data output will be audible. You can even distinguish noise from signal by listening to it with a sound card.

You can also grasp why a relatively long lead-in pulse is needed by looking at a the output in graphical form. The noise pulses tend to be of short duration so a long lead-in makes it easy to separate wheat from chaff..

[Fredrick]

When i trying to use the BS2 sampel code i does not work at all, is´t the BS2 SERIN/SEROUT comand like PBP´s SEROUT2/SERIN2?

Whats wrong.

SERIN2 reciverpin, 16468, [WAIT("!"), x.HIGHBYTE, x.LOWBYTE, y.HIGHBYTE, y.LOWBYTE]

PULSOUT TransmitterPIN, 1200 
SEROUT2 TransmitterPIN, 16468, ["!", x.HIGHBYTE, x.LOWBYTE, y.HIGHBYTE, y.LOWBYTE]

This at least works.. it counts from 0 to 255 whit maby a total off 1 - 10 numbers that are wrong, maybe thats normal and i must let that problem over to the program to handle.
And it only work whit True mode not whit Inverted...

SEROUT  transmitterpin,T2400,[synk,synk,synk,synk,9,Counter]

SERIN   reciverpin,T2400,[9],Counter

But i still wonder why the BS2 code does´t work at all, i shold do that i think?

[Luciano]

Hi Fredrick,

Are you living in a city area?
If not, it is possible that there is another transmitter within 500m?

Do you have an oscilloscope? If yes, try to see what do you get on the DATA pin
of the receiver when the transmitter is powered off.

See also these links:

LinxTechnologies.com Linx Knowledgebase - RF Modules - LR Series Long Range Wireless Communication Modules
The DATA line of the LR receiver seems to switch randomly when the transmitter is not on.
http://www.linxtechnologies.com/Supp...ation-Modules/

APPLICATION NOTE AN-00160
Considerations For Sending Data Over a Wireless Link
http://www.linxtechnologies.com/Documents/AN-00160.pdf

* * *

Before you test with the RF modules, make sure that your system works when the
two microcontrollers are connected with a 1k ohm resistor.
Make sure that the two PIC microcontrollers share the same ground. (GND).

PIC #1                 PIC #2
             1k
TX Pin-----/\/\/\------RX pin

GND -------------------GND

Best regards,


Luciano

[Fredrick]

This codes works pretty well for upp to 50 meter if the antenna of the recviver is not moving and it uses True mode and SERIN/SEROUT and it does´t work with Inverted mode????

If i´m in the range of 30 meters it does´t miss any numbers or loos the value in the variable "Check".

Why does the the Serin2 and Serout2 thats used in the BS2 sampel for these 2 modules don´t work at all.

Are you living in a city area?

No.

If not, it is possible that there is another transmitter within 500m?

I don´t think so but you never know.

Do you have an oscilloscope?

Yes at work, but not here at home.

I´m going to test later whit a wire direkt to the PIC.

Maybe this modules does´t work better and this?

What is the diffrens for the LINX modules to be driven by Inverted mode or True mode?
inverted mode (as in the BS2 from Parallax sampel) shold be the best for these modules, or?

<html>
<head></head>
<body><!--StartFragment--><pre><code><font color="#008000"><i>'****************************************************************
'*  Name    : Transmitter.BAS                                   *
'*  Author  : Fredrick                                          *
'*  Notice  : Copyright (c) 2008                                *
'*          : All Rights Reserved                               *
'*  Date    : 2008-02-13                                        *
'*  Version : 2008-02-16                                        *
'*  Notes   : PIC16F628A @ 4MHz INTORC                          *                                   
'*          : Anv&auml;nder INTORC BIT 4 1-0 FOSC 2 - FOSC0 = 1 0 0  *
'*          : TransmitterPIN = PORTB.4                          *
'*          : LEDpin = PORTB.0                                  *
'****************************************************************
</i></font>CMCON = <font color="#808080">7 </font><font color="#008000"><i>'Alla I/O Digitala
</i></font>LEDPin <font color="#000080">VAR </font>PORTB.<font color="#808080">0
</font>TransmitterPIN <font color="#000080">VAR </font>PORTB.<font color="#808080">4
</font><font color="#000080">INCLUDE </font><font color="#FF0000">&quot;modedefs.bas&quot;
</font>Check <font color="#000080">VAR BYTE
</font>Counter <font color="#000080">VAR BYTE
CLEAR

</font>Check = <font color="#808080">254

</font>Main:
    <font color="#000080">HIGH </font>LEDPin    
    <font color="#000080">SEROUT  </font>TransmitterPIN,T2400,[<font color="#808080">$55</font>,<font color="#808080">$55</font>,<font color="#808080">$55</font>,<font color="#808080">63519</font>,Counter,Check]
    <font color="#008000"><i>'PULSOUT TransmitterPIN, 1200 
    'SEROUT2 TransmitterPIN, 16468, [&quot;!&quot;, Counter.HIGHBYTE, Counter.LOWBYTE]
    </i></font><font color="#000080">LOW </font>LEDPin
    Counter = Counter + <font color="#808080">1
    </font><font color="#000080">PAUSE </font><font color="#808080">100
</font><font color="#000080">GOTO </font>Main
<font color="#000080">END 


</font></code></pre><!--EndFragment--></body>
</html>

<html>
<head></head>
<body><!--StartFragment--><pre><code><font color="#008000"><i>'****************************************************************
'*  Name    : Reciver.BAS                                       *
'*  Author  : Fredrick                                          *
'*  Notice  : Copyright (c) 2008                                *
'*          : All Rights Reserved                               *
'*  Date    : 2008-02-13                                        *
'*  Version : 2008-02-15                                        *
'*  Notes   : PIC16F872 @ 20 MHz                                *
'*                                                              *                                                              *
'*                                                              *
'****************************************************************
</i></font>ADCON1 = <font color="#808080">7 </font><font color="#008000"><i>' Alla digitala
</i></font><font color="#000080">DEFINE </font>OSC <font color="#808080">20
</font><font color="#000080">DEFINE </font>LCD_COMMANDUS <font color="#808080">3000   </font><font color="#008000"><i>'Set command delay time in us
</i></font><font color="#000080">DEFINE </font>LCD_DATAUS <font color="#808080">200       </font><font color="#008000"><i>'Set data delay time in us
</i></font><font color="#000080">DEFINE </font>DEBUG_BAUD <font color="#808080">2400 
</font><font color="#000080">DEFINE </font>DEBUG_MODE <font color="#808080">0
</font><font color="#000080">DEFINE </font>DEBUG_REG PORTC
<font color="#000080">DEFINE </font>DEBUG_BIT <font color="#808080">7   </font><font color="#008000"><i>'PORTC.7 OLIMEX RS232Board
</i></font><font color="#000080">INCLUDE </font><font color="#FF0000">&quot;modedefs.bas&quot;
</font>ReciverPIN <font color="#000080">VAR </font>PORTC.<font color="#808080">0
</font>Check <font color="#000080">VAR BYTE
</font>Counter <font color="#000080">VAR BYTE

CLEAR
PAUSE </font><font color="#808080">500

</font>Main:
    <font color="#000080">SERIN  </font>ReciverPIN,T2400,<font color="#808080">500</font>,NoSignal,[<font color="#808080">63519</font>],Counter,Check
    <font color="#008000"><i>'SERIN2 reciverpin, 16468, [WAIT(&quot;!&quot;), Counter.HIGHBYTE, Counter.LOWBYTE]
    </i></font><font color="#000080">IF </font>Check = <font color="#808080">254 </font><font color="#000080">THEN 
        GOSUB </font>LCD
    <font color="#000080">ELSE
        GOSUB </font>NoSignal
    <font color="#000080">ENDIF    
GOTO </font>Main

LCD:
    <font color="#000080">LCDOUT </font><font color="#808080">$FE</font>,<font color="#808080">1  
    </font><font color="#000080">LCDOUT </font><font color="#808080">$FE</font>,<font color="#808080">$80</font>, #Counter
    <font color="#000080">DEBUG </font>#Counter, <font color="#808080">13</font>,<font color="#808080">10
    </font><font color="#000080">PAUSE </font><font color="#808080">50    
</font><font color="#000080">GOTO </font>Main

NoSignal:
    Check = <font color="#808080">0
    </font><font color="#000080">LCDOUT </font><font color="#808080">$FE</font>,<font color="#808080">1  
    </font><font color="#000080">LCDOUT </font><font color="#808080">$FE</font>,<font color="#808080">$80</font>, <font color="#FF0000">&quot;No signal!&quot;
    </font><font color="#000080">DEBUG </font><font color="#FF0000">&quot;No signal!&quot;</font>, <font color="#808080">13</font>,<font color="#808080">10
</font><font color="#000080">GOTO </font>Main
<font color="#000080">END 
</font></code></pre><!--EndFragment--></body>
</html>

[Luciano]

What is the diffrens for the LINX modules to be driven by Inverted mode or True mode?

When Inverted logic is used there is no RF carrier while the data line is idle.
The power amplifier is activated only when a logic "1" is present on the DATA line.

This is what you have on the DATA line when you use the Inverted logic.


Best regards,

Luciano

[Fredrick]

Ok, and in True mode you have RF carrier when the DATA line i in idle.

But i´m still not understanding why its a problem to drive it in true mode, and in my case i have to drive it in true mode for inverted mode does´t work at all.