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Questions about UART communication

GPG

Sep 18, 2015
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Can you open the rar file and post that?
 

dorke

Jun 20, 2015
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The expirment most likely means there is a bug with the FSK T/R pair.:(

You can easily overcome this by sending your data in 2 bytes such that the "code" b'00000000' is never present in any byte.
That requires a mod of the software, but quite a simple one:
the 8 bit "variable" holding the leds state should be updated and fed to the leds only after 2 bytes where recived and "decoded"(assuming it is important to chnage the leds from one state to another at the same time).

Btw,
If possible, talk to the manufecter/report the bug.

About the range,are you using the proper antennas?
 
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max_torch

Feb 9, 2014
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@GPG
Logic level jumper for what?

@dorke
Im just usign the antenna that came witth the module as shown in the picture in the datasheet. I am trying to contact the vendor...
 

dorke

Jun 20, 2015
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Sounds like a problematic device.
Maybe yours only but who knows?
It is possible to test the transmitter power level and the receiver sensitivity,
but I think you don't have the equipment to do that.

You can also try changing the "T/R" channel,
sometimes it helps in cases when the cahnnel is used by neighbors or is noisy.

Defently talk to the vendor.
 

max_torch

Feb 9, 2014
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Sounds like a problematic device.
Maybe yours only but who knows?
It is possible to test the transmitter power level and the receiver sensitivity,
but I think you don't have the equipment to do that.

You can also try changing the "T/R" channel,
sometimes it helps in cases when the cahnnel is used by neighbors or is noisy.

Defently talk to the vendor.
I did try changing the channels, didnt help.
Some person suggested to me that perhaps it is working up to half a meter because that is still inside the inductive near field, and then beyond that when it stops working i have gone out of the near field and i have to keep moving farther till i reach the radiative far field for it to start working again..

Does that sound theoretically correct?
 

dorke

Jun 20, 2015
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not to me.
The antenas should be in the same polarization(ie. vertical)

From the data sheet:
Tx power 10dbm
Rx sensitvity -105dbm

The channel has to incure 120db loss, shouldn't happen in 5 metres distance.
Do you have it in open area or seperating walls?
 
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max_torch

Feb 9, 2014
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It was open area. However while i was testing i had both transceivers lying flat on table... polarization mismatch effect shouldnt even be noticeable till relatively far distance, and its not like its unidir or point to point...
 

max_torch

Feb 9, 2014
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I'm beginning to believe that perhaps I just don't know how to properly set up the antennas. Right now the antenna type is a stub antenna that came with the product. Also, how much of an impact would it have if I changed the antenna to a different ISM 433 antenna? I think a stub antenna is not the best? Here look at the pictures of my setup:
P1050480.JPG P1050481.JPG P1050482.JPG
At this distance the data is not being received. Only if I go much nearer at about 0.5 to 0.8 metre will the data be received
 
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max_torch

Feb 9, 2014
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I changed the transceivers to http://circuit.rocks/rf-serial-module-434-mhz-hc-11-1-40-cm
My problem has been solved.
I was able to transmit data at 12 metres now, haven't tested further than that. The vendor of my original transceivers did not give me any useful response.
What were the odds of buying a pair of transceivers and getting defective ones?
The new ones I bought were even half the price of the old ones....
 
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