Wireless comms using a 433TX/RX module and AtMega8

[gregmcc]

I've purchased a 433Mhz receiver and transmitter from spakfun and have used one of the links on their page to build a receiver and transmitter using the AtMega8

I can see the transmitter working and on the data pin of the receiver I can see the same waveforms being received that are being transmitter. The problem is I cannot get the LED to flash - its supposed to flash when it receives valid data.

Has anyone tried the code of this page - I"m not even sure where to start trouble shooting. All I know is the transmitter looks like its working.

I've run a LED blink test code on the microcontrollers and it works fine so it doesnt seem to be a hardware problem.

Otherwise can anyone point to me some code I can use to transmit and receive data using these modules?

 

[ckshivaram]

Basic question: can i assume the polarity of LED's are properly connected

 

[gregmcc]

Basic question: can i assume the polarity of LED's are properly connected

Yes - otherwise the blink test would not work.

 

[ctownsend]

If you want it to work 100% you can't use the usart of the atmega.

Search for manchester encoding/decoding. Writing the transmitter code is easy. Decoding is where most run into trouble. I doubt very much you will do it in C.

There are better modules that you can use that will accept data from the usart.

 

[ckshivaram]

could you try this code... we have a working for this but project is different.. meets your requirement

 

[gregmcc]

Thanks for the code - I'll have a look into it and see if I can get it going.

Just don't seem to be having luck with these 433Mhz modules.

If I can't get this going can anyone recommend a fool proof way of doing wireless comms between 2 microcontrollers. Are there better/easier wireless modules I can use?

 

[mandar_mahajan]

[QUOTE Are there better/easier wireless modules I can use?[/QUOTE]

U Can go for cc2530, series modules . But they support SPI.
Also, The modules u r using r not that much reliable. They r basically used to Tx ON-OFF pulses, which are used for door locking,etc.
The out of way is to Transmit the data more than once & receive the avg.
Ex. suppose u want to Transmit 'NAME'. ,
Transmit it as 'NNAAMMEE' & take/retrive the 0th,2nd, 4th & 6th location data from serial ISR. & Show it on ur display.

 

[ckshivaram]

. Are there better/easier wireless modules I can use?

visit

N S K E L E C T R O N I C S or

Sunrom Technologies, Your Source for Development

 

[Takeshi-san]

Could you please post photo of your project. I guess data not valid because of interferences from digital part or transmitter overloaded with modulation signal.

 

[ckshivaram]

Could you please post photo of your project. I guess data not valid because of interferences from digital part

not that problem here.... these are simple modules...

check port pins for a vaild data

 

[mandar_mahajan]

visit to Sunrom Technologies, Your Source for Development.
It provides good support.

 

[gregmcc]

I'll have a look at the modules.

For the project I'm busy with I only need to transmit one byte every minute so i could transmit the byte 3 times to make sure the correct data is being received.

 

[mandar_mahajan]

Dear gregmcc ,
What data is there in ur 1 byte.? Is it some information means any adc/dac or any other perriferal data/output or just ON-OFF Pulses.??
The good practice is to Transmit the data contineously, & on receiver side store it in some buffer & take whenever u want.

transmit the byte 3 times to make sure the correct data is being received.
If there is still prob. then tx data like i said. But it is just a temprory solution.
firstly u have to check the Tx Pulses on Scope & compare with the Rx.
Post ur results.

 

[gregmcc]

I've got a sensor that counts the number of LED pulses and transmit the value every 60 seconds. The value will be around 30 to 60 decimal.

The receiver will receive the data via 433Mhz wireless and output the value received via RS232 to the PC.

I'll check the pulses and post results tonight.

 

[matthijsfh]

Hai,

I am using the RFM12 modules (also 433 MHz) and having good results with that (see my link in the signature). My code is based on code fragments I found on the internet.

Would these RFM12 modules be an alternative for you?

Greetings Matthijs