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Help needed for data transmission over wireless

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Rajaneesh

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Dear Folks...

I wanted to send a serial data to a wireless module which has standard serial port and general purpose digital i/o too. The problem here is, my incoming serial data baud rate is not standard, it comes around 150bps.

I tried to feed this data to the digital I/O, but it doesn't replicate in the other end because the i/o scan rate is very low.

Is there any other alternative way to send this data by any means.....

welcome Your valuable guidance ...

Thanks in advance
 
Assuming your modules are compatible with standard serial (most aren't), then use a PIC to convert from 150bps to 1200bps (or whatever the modules require).
 
RE : Help needed wireless data transmission

Hi Niegel,

Thanks for your positive response...

The wireless module has standard serial port(110 bps --- 115200bps). The problem is cited below for your kind ref..

The serial data (150 bps) , has no start / stop bit and no frame. So iam not able to arrive a solution how to convert it from 150 to 1200 or any other standard serial baud rate.

Expecting your valuable guidance...

Thanks again...
 
Can you tell us what modules you are using, and what form the data is in?

If there are large gaps in the data, you will get noise from the receiver during the gaps. You have to arrange a preamble on the start of the data.
 
RE : Help needed wireless data transmission

Hi Driver300....

The radio engine is 802.15.4 core. It has freescale MC13213 controller..

The data which has to be send is 150bps. I have attached the waveform captured...please go through...

Thanks ...
 
Can you tell us what modules you are using, and what form the data is in?

If there are large gaps in the data, you will get noise from the receiver during the gaps. You have to arrange a preamble on the start of the data.


Sorry...it seems the files are not attached.... sending again...for your ref..
 

Attachments

  • data signal.pdf
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Asyncronous serial needs some way to identify the start of a data byte (or whatever size it sends), your first task is to completely reverse engineer what ever it's doing - what's it from anyway?.
 
Re

Asyncronous serial needs some way to identify the start of a data byte (or whatever size it sends), your first task is to completely reverse engineer what ever it's doing - what's it from anyway?.


Hi Niegel...

Its a beacon, and i can monitor the status from master unit which communicate with the beacon through wire. At present it is communicating in FSK over the cable. I wanted to convert to wireless mode. Here iam unable to demodulate the FSK signal(I dont have exposure to FSK), so trying to take the serial data coming before the FSK modulator/demodulator and feeding the same to wireless module... Hope i made you clear...

Expecting ur guidance...still...

THanks
 
Can you tell us what modules you are using, and what form the data is in?

If there are large gaps in the data, you will get noise from the receiver during the gaps. You have to arrange a preamble on the start of the data.


Hi

please let me know your views ...
 
Please explain how you can tell when the data is being sent, or is the first bit always the same (a "1")?


There is a start bit, you can see in the waveform.... a transition from High to low indicates that the transmission started... rest is the data bits.... and 74ms is the latency....

Any idea?
 
Some ideas - The best if possible: get the circuit to output your desired baud rate.

Assuming that its already been built and that your RF channel cannot accommodate such a low data rate, get a microcontroller, such as the Atmel ATTINY2313, which has one UART -use that UART to send your higher speed output data in a standard format, and then use a firmware UART to receive your nonstandard (about 150 baud) input code. If there is no handshaking between the gizmo that generates the approx 150 baud stream and the RF link, then it would be really simple.
 
Some ideas - The best if possible: get the circuit to output your desired baud rate.

Assuming that its already been built and that your RF channel cannot accommodate such a low data rate, get a microcontroller, such as the Atmel ATTINY2313, which has one UART -use that UART to send your higher speed output data in a standard format, and then use a firmware UART to receive your nonstandard (about 150 baud) input code. If there is no handshaking between the gizmo that generates the approx 150 baud stream and the RF link, then it would be really simple.


I tried this method in the beginning itself....but the problem here is the latency...

The original system need the continous signal from the source...if it missed for more than 74ms (communication latency), it will start triggering the alarm. Here there is no proper packet frame...hence im unable to properly...

Another method i tried is, sending a continous definite charactor for a high in the input signal and another charactor for a low in the input. That has done the maximum speed of the module 115200 baud... and the rf baud is 250 kbps..... but still it gives some delay...in the receiving end..

Any innovative idea...appreciated....

Thanks in advance
 
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