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I need to transmit a string of message between two Radio frequency transmitter. The message will be stored a microcontroller (e.g. 8051). How to go about writing a program for it and how to interface between the micrcontroller and the transmitters. I am still an amauteur when comes to embeded programming. Any source code or info on this ?
What do you mean by interfacing? Ther devices I listed earlier just transmit RS232 data over wireless. It is no different interfacing to these than it is to hook up your 8051 to a PC. Some of the higher end RF modules might require that you send it AT style commands (modem style) to initialize their baud rates, transmit power etc. So look up some data sheets, read some manuals and application notes. As for code samples...Code tends to be rather specific. Need more information.
Manoj, let's just clear a few things. First of all, I'm talking about RF Transceivers like the Aurel XTR-434, Radiometrix BiM2, RF Solutions RXQ1 etc. These modules operate at 433 MHz and some on 868 MHz. These are license-free modules, and it's range is limited to +/- 200m. These modules have a RX and TX, RX_ENABLE, TX_ENABLE, and CARRIER_DETECT. You have to write code to interface them properly! You still use the serial port to send and receive the data, but you have to manage the control signals as well. No problem, you save money and who's afraid of programming? Anyway, at some point modules differ. So you need to revise code. I'm trying to write some code for this modules, and simple RF transmitters, RF receivers, which can be re-used. This simplifies the development significantly. I don't know which model of Linx, or Maxstream you used, but let me know, and I'll check it out. Kind regards Christo v.d. Merwe
Hi Christo. My personal favorite wireless unit is from a company called MicroHard in Calgary. They make a 900MHz unit with up to 1 Watt of transmit power. http://www.microhardcorp.com/products_oem_compactrf.htm We just did some range tests with it and we can easily go a 1/2 Km at 0.1 Watt (line of sight). And we could probably go several Km with the proper antenna hardware at 1W. It is not cheap though...about 750$ a pair + Antennas. Have also used the Linx Wireless SC-PA but find it rather weak for what we do. It is however very low cost (30-50$ range) http://www.linxtechnologies.com/ldocs/pdfs/scpamanual.pdf Both these are license free and precertified (and therefore require no FCC certification). Will look at the Aurel part you are using.
Christo, I am interested to program a PIC for RF data control and hope that I can reference your completed software. Do keep me updated and if possible, email me a copy of your software codes. thks.
Sorry for re-posting but I seriourly need help in interfacing two PIC by means of wireless RF data transfer. Anyone able to offer me help? Thks in advanced.
"but I seriourly need help in interfacing two PIC" Better find a PIC forum, then!
Clarence, here's a site which contains some very useful routines. It is written in C for a PIC compiler(CCS). Kind regards
Can i have a RF transmitter and receiver circuit.. need it badly for my project. Thanks
http://instruct1.cit.cornell.edu/courses/ee476/FinalProjects/s2003/lph2/WirelessKybd/index.html
How can i use this modify this circuit to jus transmit without using keyboard? any idea?? My project purpose is to detect range...
The one mentioned above is used as a medium of transmission you can use it even in RS-232 comminication... If you can give some more details may be I can help
The one mentioned above is used as a medium of transmission you can use it even in RS-232 comminication... If you can give some more details may be I can help... Rgds Raj Shetgar
Ok.. My project specs I need to design a RF transmitter circuit and a receiver circuit. the transmitter should be transmitting signal(can be data also) at all time. If the receiver cannot detect the signal or out of range, the receiver will sound a Buzzer and light a LED. the buzzer and LED is done... so i need the transmitter and receiver circuit...
Actually i got a circuit which use Ultrasonic transducer. But it can only detect when the transducers is in line of sight... so i decided to use RF.
Hi, What you need to do is decide on a protocol...may be you have to use 2 pairs of trans. and recev. When ever a receiver receives a command it has to send back some other character...if this character is recevied by the other trans. it means that the unit is within a specified range. For this you can make use of the USART. The above modules support RS-232. Any thing else... Rgds Raj Shetgar