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Digital signal in FM frequency
Posted: Wed Jul 20, 2011 6:00 am
by Enigma
Hi Guys
My elder sister's son is 5 yr old and he is pretty good at breaking things
. So few dayz ago he got a new toy car and of course he broke it within one day. Its with me now and planing to turn that car in to a remotely controllable one. I know little about digital electronics. But my knowledge in analog electronics is ground zero
. So I'm planing to use digital electronics for this. But the only issue is the transmitter and receiver. Is it possible to modulate a digital code in a FM carrier frequency ? If so can any give me an example or any information regarding this ?
If not what is best way to achieve this ?
Thanks
Re: Digital signal in FM frequency
Posted: Wed Jul 20, 2011 7:56 am
by Nipuna
I don't know much friend.
But since you are lack of free time, How about buying a unit(Remote controller and Receiver) from eBay?
Re: Digital signal in FM frequency
Posted: Wed Jul 20, 2011 9:11 pm
by Rksk
Hi,
it's a nice idea
1st, did u checked that how it works? can you put some pictures of it? we will can talk on it. anyway it seems this topic is not suitable
BTW, If you can build digital side of both of remote control & the toy, it's very easy to build
the transmitter & receiver for it.
you can find a small fm microphone & a fm reciever circuit from an electronic shop easily. also if you are interested in building ciruits you can try one like below one. but building a fm reciever is not a good idea.
- http://sound.westhost.com/project54.htm
- p54-f1.gif (4.95 KiB) Viewed 11778 times
[ Post made via Mobile Device ] 
Re: Digital signal in FM frequency
Posted: Thu Jul 21, 2011 7:58 am
by Shane
I found it is hard to make RF transceivers even with years of expereince. Even it is a kind of worthless when the working guaranteed modules are already available.
- nRF24L01.jpg (21.67 KiB) Viewed 11770 times
NRF24L01 Wireless Transceiver Module is one good example. You can buy two of them for < $8 and I'm sure it will cost you more to even build one. Have a look at this eBay deal.
http://cgi.ebay.com/Arduino-NRF24L01-Wi ... 415b5fd1b8.
The coding would be very easy.
TX mode:
Code: Select all
void setup()
{
SPI_DIR = ( CE + SCK + CSN + MOSI);
SPI_DIR &=~( IRQ + MISO);
Serial.begin(9600);
init_io();
TX_Mode();
}
void loop()
{
unsigned char status=0;
unsigned char key=0;
for(;;)
{
tx_buf[1]=key;
key++;
status=SPI_Read(STATUS);
if(status&TX_DS)
{
SPI_RW_Reg(FLUSH_TX,0);
Serial.println(tx_buf[1],HEX);
SPI_Write_Buf(WR_TX_PLOAD,tx_buf,TX_PLOAD_WIDTH);
}
SPI_RW_Reg(WRITE_REG+STATUS,status);
delay(1000);
}
}
RX mode:
Code: Select all
void setup()
{
SPI_DIR = ( CE + SCK + CSN + MOSI);
SPI_DIR&=~ ( IRQ + MISO);
Serial.begin(9600);
init_io();
RX_Mode();
}
void loop()
{
unsigned char status=0;
unsigned char key=0;
for(;;)
{
tx_buf[1]=key;
key++;
status=SPI_Read(STATUS);
if(status&TX_DS)
{
SPI_RW_Reg(FLUSH_TX,0);
Serial.println(tx_buf[1],HEX);
SPI_Write_Buf(WR_TX_PLOAD,tx_buf,TX_PLOAD_WIDTH);
}
SPI_RW_Reg(WRITE_REG+STATUS,status);// clear RX_DR or TX_DS or MAX_RT interrupt flag
delay(1000);
}
}
You can find a sample TX, RX code here:
If you really want to build it yourself, you can find the schematic in the following archive.
More information can be found in
Arduino site.
Re: Digital signal in FM frequency
Posted: Thu Jul 21, 2011 8:44 am
by Saman
I agree with Shane. I have another idea. How if you buy a R/C toy (car, boat, etc...) for about LKR 500 (US$ 5) and modify the circuit for your need?
Re: Digital signal in FM frequency
Posted: Thu Jul 21, 2011 6:44 pm
by Rksk
Saman wrote:I agree with Shane. I have another idea. How if you buy a R/C toy (car, boat, etc...) for about LKR 500 (US$ 5) and modify the circuit for your need?
there is no anything to do, just play with new toy
I have suggested to buy a small fm microphone (LKR100) and a FM reciver circuit (LKR200). You can tune them and use with a areal.
[ Post made via Mobile Device ]
Re: Digital signal in FM frequency
Posted: Thu Jul 21, 2011 8:34 pm
by Saman
I have suggested to buy a small fm microphone (LKR100) and a FM reciver circuit (LKR200). You can tune them and use with a areal.
Guess it will make things complicated. It would require a DAC and a ADC on both sides (if two way communication is required) which will increase the cost. All-in-one ICs are common these days. These ICs have both DAC and ADC built-in in addition to the transceiver. I guess Rksk is clear on the point now. Even if we establish a radio link, there should be a way to send signals from one end to the other. This is where we need to spend some more money on doing DAC and then ADC. If it is me, I would get this approach since making things is more fun than buying things for an engineer.
I have found one for even less ($2.99 per side) at
http://cgi.ebay.com/RF-2400W-2-4GHz-Wir ... 0706930116.
there is no anything to do, just play with new toy
What you are saying has a point. Why not we play with this one
One point is this. The R/C cars available for LKR 500 are very cheap. No need to say this. Steering is so bad on these. So if Enigma has a better car, it is worth to get the things moved carefully. The main point is not that. If Enigma takes the first approach, he would learn quite a lot of things by playing with uCs, etc... while having quite a lot of fun.
Buying a R/C car for LKR 500 will be cost effective for this project.
Re: Digital signal in FM frequency
Posted: Thu Jul 21, 2011 11:05 pm
by Enigma
wow this is great guyzz. Now I have options. Thank you all.
Re: Digital signal in FM frequency
Posted: Tue Aug 23, 2011 8:54 pm
by SemiconductorCat
this is a circuit that I also looked for a long time. thanks.
There are modules to do it but those modules/chips are not available in the SL markert.
