Help with RC car Transmitter and Reciver . - Electronic Circuits Projects Diagrams Free

sonu2die4 · 19th February 2007, 03:24 PM

Hi,
I am Vivek and I want to establish a radio link between two atmel Microcontrollers . I will be using the UART of both the AVR. I have fabricated the necessary electronics .

I had an old working RC car working on 49 Mhz , of which I am using the Transmitters and Receiver to connect to the appropriate pins of the Microcontroller .

I have also seen schematics with transmitter modles # RCT -433 AS and # RCR-433 RP . These transmitters are little expensive . soi want to avoid using it .

But my question is can I use My existing RC TX/RX to send the Data packets in the same way over the Radio interface as the expensive Radio modules without any data loss?
Regards
Vivek

**Nigel Goodwin** · 19th February 2007, 04:18 PM

Probably not?, and in either case it's probably not a good idea to use the UART's - you need to implement some type of NRZ coding, such as Manchester coding, and a packet system. Using a UART makes this much more difficult.

sonu2die4 · 19th February 2007, 05:44 PM

thanks ..however i would be able to send some bits anyhow??

**Nigel Goodwin** · 19th February 2007, 05:54 PM

Quote:

Originally Posted by sonu2die4

thanks ..however i would be able to send some bits anyhow??

Probably! - but as to how far, and how reliably?.

sonu2die4 · 19th February 2007, 05:57 PM

Hi,
See I just want to test a small project where I just want to glow 8 leds ( Data) over a wireless network. the distance would be just 2 meters. This is yja main reason i posted here.

**Nigel Goodwin** · 19th February 2007, 06:15 PM

Try it and see!.

Sceadwian · 20th February 2007, 12:04 AM

Should work fine. You should be able to get 1200/2400 baud for good distances, higher at shorter distances though it wouldn't be as reliable. Seeing as how R/C systems are already set up for FSK you can send serial data directly over it without having to bother with Manchester encoding. If your TX has a 'buddy box' ability you can use that to directly hijack the PPM stream without having to open the internals up. Tapping the receiver isn't overly difficult, inside your receiver one leg of the IC is going to have the entire PPM baseband signal on it, you can feed that directly into an I/O pin. Just add a little bit of error checking/correcting data to the transmitted packet (maybe as simple as sending each byte twice and comparing it) and you should be able to do quiet a bit more than just blink 8 LED's with it.
I have an RC transmitter and receiver I bought with the specific intention of doing just that, but I haven't finished the project yet for lack of space to complete it (Living with my fiance in a small apartment no space for a workbench) The last thing I did was open both tx and rx up and check where to tap the signal, was easy to find on a scope. If you have any more questions or need assistance feel free to add to the thread or send me a private message.

sonu2die4 · 20th February 2007, 01:55 AM

Thank you very much. Its good to see you thread.
Actually I am building a wireless data transmitter . I want to send an ASCII bit over the air interface.
Now suppose I want to send 'A' then I may want to send it serially to another microcontroller . Hence I will end up in sending binary value of A over the air interface . So this is what I want to do.
Regards
Vivek

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19th February 2007, 03:24 PM	(permalink)
sonu2die4	Help with RC car Transmitter and Reciver . Hi, I am Vivek and I want to establish a radio link between two atmel Microcontrollers . I will be using the UART of both the AVR. I have fabricated the necessary electronics . I had an old working RC car working on 49 Mhz , of which I am using the Transmitters and Receiver to connect to the appropriate pins of the Microcontroller . I have also seen schematics with transmitter modles # RCT -433 AS and # RCR-433 RP . These transmitters are little expensive . soi want to avoid using it . But my question is can I use My existing RC TX/RX to send the Data packets in the same way over the Radio interface as the expensive Radio modules without any data loss? Regards Vivek

19th February 2007, 04:18 PM	(permalink)
Nigel Goodwin	Probably not?, and in either case it's probably not a good idea to use the UART's - you need to implement some type of NRZ coding, such as Manchester coding, and a packet system. Using a UART makes this much more difficult. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

19th February 2007, 05:44 PM	(permalink)
sonu2die4	thanks ..however i would be able to send some bits anyhow??

19th February 2007, 05:57 PM	(permalink)
sonu2die4	Hi, See I just want to test a small project where I just want to glow 8 leds ( Data) over a wireless network. the distance would be just 2 meters. This is yja main reason i posted here.

19th February 2007, 06:15 PM	(permalink)
Nigel Goodwin	Try it and see!. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

20th February 2007, 12:04 AM	(permalink)
Sceadwian	Should work fine. You should be able to get 1200/2400 baud for good distances, higher at shorter distances though it wouldn't be as reliable. Seeing as how R/C systems are already set up for FSK you can send serial data directly over it without having to bother with Manchester encoding. If your TX has a 'buddy box' ability you can use that to directly hijack the PPM stream without having to open the internals up. Tapping the receiver isn't overly difficult, inside your receiver one leg of the IC is going to have the entire PPM baseband signal on it, you can feed that directly into an I/O pin. Just add a little bit of error checking/correcting data to the transmitted packet (maybe as simple as sending each byte twice and comparing it) and you should be able to do quiet a bit more than just blink 8 LED's with it. I have an RC transmitter and receiver I bought with the specific intention of doing just that, but I haven't finished the project yet for lack of space to complete it (Living with my fiance in a small apartment no space for a workbench) The last thing I did was open both tx and rx up and check where to tap the signal, was easy to find on a scope. If you have any more questions or need assistance feel free to add to the thread or send me a private message. __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har." Last edited by Sceadwian; 20th February 2007 at 12:14 AM.

20th February 2007, 01:55 AM	(permalink)
sonu2die4	Thank you very much. Its good to see you thread. Actually I am building a wireless data transmitter . I want to send an ASCII bit over the air interface. Now suppose I want to send 'A' then I may want to send it serially to another microcontroller . Hence I will end up in sending binary value of A over the air interface . So this is what I want to do. Regards Vivek