RF Transmitter and Receiver

Intro: RF Transmitter and Receiver

In this project, I will use RF modules with Pic 16f628a. It will be a short tutorial about rf. After you learn ho rf modules communicate with each other you can use these modules with pic microcontroller, ardunio or any microcontroller. I controlled RGB LEDs but If you can control many thing motors or relays.

STEP 1: Short RF Lesson

What is RF?

In short term, radio frequency (RF) refers to the rate of oscillation of electromagnetic radio waves in the range of 3 kHz to 300 GHz, as well as the alternating currents carrying the radio signals.

How does it work?

We need two modules which are transmitter and receiver. Our control our data 1 and 0(we use the microcontroller in this project) and transmitter send these data in Seri way in radio waves. After ıt started broadcasting, receiver collect these radio waves and it gives as 1 and 0 again.

Why do we use it?

If we want to communicate some devices without any wire we RF modules is one of the ways.

STEP 2: Circuit Schemas

In the first circuit is the transmitter second is receiver.I controlled 3 RGB led by this modules.

STEP 3: Component List

Transmitter Part:

1. pic16f628a
2. 18pin dip socket
3. 1n4001 diode
4. lm7805
5. 220 uf 16v electrolytic cap
6. 1 uf cap
7. 330ohm ^1
8. 4.7k ohm ^1

9. Rf transmitter (433 MHZ)

10. 10k ohm ^4
11. 4 push button
12. 5mm led
13. male header

Receiver Part:

First eight is the same

9.RF receiver (433 MHZ)

10. 5mm RGB led ^3

11.led

12male header

Note:RF modules must be same frequency.

Rf modules link of rf modules

STEP 4: Printed Circuit Board

I love using PCB instead of prototype PCB(including many holes), In my opinion, this way is more healthy for circuits. After designing the circuits I printed on the boards but there are some tiny nets so I needed to fix some nets. After fixing operations they go to in acid. Then they are ready for next step.

STEP 5: Solder Mask !

Its optional part.

Solder mark has some difficulties but otherwise, it has some benefits.Your PCB can be healthy very long time and short circuit risks become increases.You can find many resources about how can you make solder mask at home.After the solder mask operations, PCB's go drilling operations.

STEP 6: Soldering

At last, we soldering the components on PCB. My advice you should solder dip socket first but attach the pics and rf modules after soldering. You should be very careful about short circuits. Besides, rf modules can be effected static electric very easily.

STEP 7: Codding

I used PIC CCS for programming. If you have any question about anything just ask it, please.

First, we choose the baudrate you should look that for rf modules datasheet then we define transmitter an receiver pins. Parity is about our data is odd or even but we don't use it in this project, at last, we choose 1 our stop bit.

Preamble Function:

If we try to use the same many RF modules in the same area it will be some provision. We prevent this problem with preamble function. We define an identification for our modules and sent it receiver module.

We can see this function on the oscilloscope.First two pic belong transmitter and second modules belong receiver circuit

STEP 8: RUN!

In this project main idea was RF communication thus I did not use qualification pic or oscillator. If you want to obtain better communication you should use high-frequency crystal oscillator and high-frequency RF modules. You should use an antenna.

Comments

[cesarviloria2022]

Hello, I like your project, but I see you had to program a code in the RF modules. Why did you use a code for that? If the transmitter and receiver have the same frequency they should be capable to communicate with each other just by powering ON both circuits. Am I right? Also, I would like to know if you have any gerber files for the Tx and Rx circuit for making the PCB's. It is easier to order them than to play with acids and that stuff to make the printed boards. Thank you.

[Prominent]

Hello here.
Pls am planning a project whereby I want to make a wireless system that will transmit when a water detector detects water. I was thinking of using the knowledge of this transmitter and receiver with a water detector chip. Pls can I get help from you?

[AlC70]

Be aware that 433 MHz is within the LICENSED UHF amateur radio bands. I license is required to use these frequencies (420 - 450 MHz) at any power level. One of the national hobby shops was recently fined several million dollars for marketing drones that use these frequencies and don't warn consumers about the "non type accepted" products. There are exceptions, just be sure to check with your local authorities before transmitting on these frequencies.

[eburman]

Seriously? Get of your high horse! These units put out a minuscule signal. It's not enough to even make it outside the walls of my house. What value is there in your comment? You say "check with your local authorities." Which authorities? Are you able to provide so much as one legitimate example of someone who has been prosecuted by the FCC for using one of these units? Citations please.

[steve.6250.00]

Is 433MHz legal in USA?

The FCC prohibits the operation of wireless microphones and similar devices (e.g., wireless intercoms, wireless in-ear monitors, wireless audio instrument links, and wireless cueing equipment) in the 700 MHz Band, i.e., 698 - 806 MHz. But the frequency for this UHF-938 wireless system is 433MHz . So it is legal .

[JCFLindsay]

I want to play with ham/SW radio reception. Can you recommend a place for beginners to learn, and how to purchase equipment?

[JimG50]

For info and books about Amateur Radio (Ham Radio) see ARRL.ORG. For equipment google ICOM, Yaesu, Kenwood or go on Ebay searching for amateur equipment. Or build your own. 73. JIm

[DavidH1070]

do you have a reference for these rules that a layman could reference?

[e5frog]

433MHz is a license free band in the EU for low effect (LPD433). In Sweden (possibly wider area, don't know) the allowed band is 433.050 - 434.790MHz and you often find them in cordless headphones, remote light/power switches etc

[sanketmore164]

HELLO,
IM TRYING TO MAKE THIS PROJECT,
BUT IT NOT WORKING
IM USING BOTH TRANSMITER AND RECEIVER CIRCUIT IN SAME BREADBOARD,AND SAME POWER SUPPLY,PLZ HELP ME WITH THIS,,,WHAT CAN I DO,

[OEsirik]

Are you sure same transmitter and receiver pinout?

[sanketmore164]

yes,as per your circuit diagram,i make same circuit.

[sanketmore164]

problem solved

[sanketmore164]

thanku for this project

[sml.bustos]

Great job, man !
But... There is not decode section of preamble in the "rf receiver.c"

[NavodJ]

Can you give a clear photo of circit board

[mina_adel_85]

kindly advice please , can we use the above circuit for controlling DC motors

[OEsirik]

Yes, you can use with little bit update.

[MeanFacedP]

Could this be used to repeat a control signal from a RGB LED Strip? I'm trying to think of ways to create synchronized lighting while connected to different power sources. I have been trying to check into Zigbee or Zwave, but i'm not seeing how it could be setup. From everything I have seen with RF it has been setup as a control from one to the other. Though, in simple IR usage now that I think about it the controllers aren't set to independent control and would take the same remote. So multiple IR receivers or blasters would work.

[OEsirik]

I guess yes, it can be use for that