comm 433 picaxe =08M2

friis

Senior Member
Hi Goeytex,
I have added the antennas and changed the receiving pgm as follows:

#Picaxe 08M2
#Terminal 4800
main:
Do
high c.2
pause 1000
low c.2

SerIn C.4, T2400, b0 ;("X"), b0
SerTxd( "Received ", #b0, CR, LF )
Loop

When I load the pgm I get a 2 sec. flash and nothing more. If I remove the power, I get a 2 sec. flash and the terminal writes. Received 0 - evidently the pgm has passed SERIN and executed SERTXD - without pwr?. I can go on doing this. I hav'nt tried SerIn C.4, T2400, b0 without the antennas.
I dont have a clue!
torben
 

friis

Senior Member
Hi Goeytex,
No, not without pwr - the 08M2 is powered. The situation is the following:
If the data line from the RX is not connected, the LED flashes regularly and the terminal writes: Received 0.
If the data line from the RX is connected and I interrupt the dataline, the terminal writes - say - 252. Then it goes on writing "Received 0".
If the data line from the RX is connected everything goes dead.
It appears that the SERIN when it receives something from the data line it is not what it expected to receive - but it is receiving something.
The distance between TX and RX is about 3 meters and antennas installed.
Is there a way in which I can read the receive buffer and display it with SERTXD?
FRIN/FROUT are not implemented for the 08M2.
torben
 

sghioto

Senior Member
If the data line from the RX is not connected, the LED flashes regularly and the terminal writes: Received 0
This doesn't make any sense. The line
Code:
[COLOR=#3E3E3E]SerIn C.4, T2400, b0 ;("X"), b0[/COLOR]
does not have a timeout provision included, so why would the next line
Code:
[COLOR=#3E3E3E]SerTxd( "Received ", #b0, CR, LF )[/COLOR]
be executed?




Steve G
 

hippy

Technical Support
Staff member
Without a qualifier in the SERIN command it will simply receive random RF noise as if data. Disconnecting or interrupting the RX wire will likely leave the SERIN pin floating, also causing random data to be received.
 

erco

Senior Member
@friis: Sounds like you are getting your protocols sorted out.

I am about to start using some of these myself and and have done some Googling. With 17 cm antennas (as Goeytex said back in post #38) they are capable of good range, like 100meters: http://vanceance.blogspot.com/2014/01/xy-mk-5v-arduino.html

Numerous sites (including that last one) say that the range can be increased by increasing the transmitter voltage over 5VDC. No surprises there, more voltage is more power, like using a bigger hammer: http://forum.arduino.cc/index.php?topic=199134.0

But some say that the receiver works better on 3 volts. From http://arduinobasics.blogspot.com/2014/06/433-mhz-rf-module-with-arduino-tutorial.html : While using 5V for VCC on the receiver, I would get a lot of interference, however with 3V, I hardly got any noise. If you find you are getting unpredictable results, I would suggest you switch to 3V on the receiver and move the transmitter and receiver modules right next to each other. Remember this is just a check... you can experiment with an antenna or a greater distance afterwards.
 

Goeytex

Senior Member
Hi Goeytex,
No, not without pwr - the 08M2 is powered. The situation is the following:
If the data line from the RX is not connected, the LED flashes regularly and the terminal writes: Received 0.
If the data line from the RX is connected and I interrupt the dataline, the terminal writes - say - 252. Then it goes on writing "Received 0".
If the data line from the RX is connected everything goes dead.
It appears that the SERIN when it receives something from the data line it is not what it expected to receive - but it is receiving something.
The distance between TX and RX is about 3 meters and antennas installed.
Is there a way in which I can read the receive buffer and display it with SERTXD?
FRIN/FROUT are not implemented for the 08M2.
torben
Disconnecting the RX line and leaving the serin pin on RX floating is a bad idea. So is eliminating the qualifier. Therefore, your setup/code is non-nonsensical and will not help you diagnose your problem.

Adding to that, the wiring mess on your TX board looks like a bowl of spaghetti with excessively long wires of random colors running all over the place, making the wiring difficult to check & confirm. Common practice is to use black wires for ground and red wires for +V/Vcc. The wires should be as short as possible on TX board as well as on the RX board. This is to prevent stray capacitance from affecting the circuit(s). On the TX board, the bypass capacitor is too far from the Picaxe and should connect directly across the Picaxe +V and 0V on on the Picaxe.

In nutshell you are doing just about everything wrong. It is also possible that you have blown the TX module or the RX module and that it will never work. This should not take 4 pages of support to get working.

Look at the images below. These are examples of a good way of wiring up breadboards. Note the organized layout, the wire colors, and minimum lengths. You will need 22 ga solid hookup wire instead of the long jumpers.
 

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friis

Senior Member
Hi sghioto,
I think it is because whatever is in the receive buffer is readable by the SERIN.
torben
 

friis

Senior Member
comm 433=08M2

Hi Goeytex,
I send you photos of my cleaned-up setup.
Unfortunately one of my 08M2s has broken down - i cant load the pgm anymore - so I have to order a new one (or two).
Is it really true that there is no way to look in the buffer and see what has been received?
torben
 

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hippy

Technical Support
Staff member
Is it really true that there is no way to look in the buffer and see what has been received?
There is no buffer as such when using SERIN. Whatever is received will be put into a SERIN variable.
 

Goeytex

Senior Member
The boards look much better

Unfortunately one of my 08M2s has broken down - i cant load the pgm anymore
This may be because of a long pause in the program or other program conditions that prevent programming. You should try a "hard reset". See Manual 1 (Page 50)

If ordering new chips, I suggest getting 14M2 so that you can use the RFOUT and RFIN commands. And while you are at it you could go to EBAY
and get some DORJI RF ASK modules. These are better quality but more expensive.

Dorji TX Modules

Dorji RX Modules

THESE look good as well.
 

eclectic

Moderator
I may be missing something (not new), but
post #49, the photo of the AXE091 board...

1. Where is the power supply for the breadboard?

2. The wiring for the corner section ?

e
 

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Goeytex

Senior Member
Look at the image below from the receiver and tell me what resistor value this is? It looks to be 33 ohms to me. It that a black band or a brown band?

It could be because of the off color and shadowing, but in any case a 1K or even a 2K2 resistor will light a RED LED plenty bright and will reduce current.
There is no need to drive the LED at the Picaxe maximum current with a 330R resistor.
 

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friis

Senior Member
Hi hippy,
But then it has'nt received anything. It is looking for the "X" and does'nt find it. The b0 could be anything.
torben
 

hippy

Technical Support
Staff member
Hi hippy,
But then it has'nt received anything. It is looking for the "X" and does'nt find it. The b0 could be anything.
Not sure I understand what you are saying there. Your original code was ...

SerIn C.4, T2400, b0 ;("X"), b0

I am not sure if that is what you are using but if so then the semi-colon comments the qualifier out, leaving ...

SerIn C.4, T2400, b0

That results in the SERIN waiting for anything it might consider to be a data byte, reading it, placing it into b0, then continuing. RF noise or disconnecting the wire to C.4 can fool the SERIN into thinking a data byte has arrived.
 

friis

Senior Member
Hi Goeytex,
The hard reset did'nt work - I have ordered 14Ms
I have ordered the Dorji modules.
I will be back as soon as I have the stuff.
torben
 

friis

Senior Member
Hi Goeytex,
The hard reset did'nt work - I have ordered 14Ms
I have ordered the Dorji modules.
I will be back as soon as I have the stuff.
torben
 

friis

Senior Member
Hi hippy,
Here is the pgm I used:
#Picaxe 08M2
#Terminal 4800
main:
Do
high c.2
pause 1000
low c.2

SerIn C.4, T2400,("X"), b0
SerTxd( "Received ", #b0, CR, LF )
Loop

torben
 

friis

Senior Member
Hi Goeytex,
It's a 330 Ohm resistor. I noticed you had a 1 kOhm resistor. Is that what you would recommend?
torben
 

friis

Senior Member
Hi everybody,
I got a set of 14M2 (using rfout/rfin) and a set of ARDUINO TX/RX and it appears to work. I must somehow have destroyed two receivers. I have tested the transmission over a distance of 2.5 meters. I have also got the dra886rx/dra88?tx, but hav'nt set them up yet. I expect no problems there.
Thanks for all the help you have given me!
torben
 
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