sparkfun 434mhtz transmitter and reciever

[blackbeard]

so i got these things but i have no idea how to use them. i know nothing about transmitters but i really want to give these things a try.

[img=http://img27.imageshack.us/img27/4323/dscn7186m.th.jpg]

[kd5kfl]

i know nothing about transmitters

obviously.

these are squarely in the middle of the 70CM amateur radio band.

the FCC is not going to call in the SWAT team to take you down over this. just thought you would want to know.

[blackbeard]

duh... *caveman head scratch*

[billhowl]

Good AVR Tutorial on Running TX433 and RX433 RF modules with AVR microcontrollers
http://winavr.scienceprog.com/example-avr-projects/running-tx433-and-rx433-rf-modules-with-avr-microcontrollers.html
http://www.sparkfun.com/datasheets/RF/KLP_Walkthrough.pdf
http://narobo.com/articles/rfmodules.html
http://www.open.com.au/mikem/arduino/VirtualWire.pdf

[blackbeard]

oh thanks allot!

[blackbeard]

ok after reading all that i still don't get it. is there any way to dumb it down?

[billhowl]

Which part that you don't get it? how to use them? or what & where to use them?
This sparkfun 434mhtz transmitter and receiver is a one way RF link to send some data for remote sensing and control. 

[blackbeard]

i don't really understand whats being transmitted. what input do i need to create any given output? i don't understand what part of it is 2.4 ghtz and what is 434 mhtz.  i also don't really understand what the sample code is doing and so i can't really make my own. anyone know any examples of how it's used by any chance?

[Soeren]

i don't understand what part of it is 2.4 ghtz and what is 434 mhtz.

None!
m is milli, M is mega, G is giga and it's Hz for Hertz, so it is MHz and GHz.

Alltogether, it sounds like you have a long way to go, before you even think about touching HF circuits. Better grind your teeth on something where you have a greater chance of success.

[blackbeard]

i don't understand what part of it is 2.4 ghtz and what is 434 mhtz.

None!
m is milli, M is mega, G is giga and it's Hz for Hertz, so it is MHz and GHz.

Alltogether, it sounds like you have a long way to go, before you even think about touching HF circuits. Better grind your teeth on something where you have a greater chance of success.

i'd rather get this working and be able to repeat it then work on something simpler yet inferior and be no closer to having a device that suits my needs. as for the notation i think you know what i meant

[Spoil9]

Okay, I'll bite. What's this going to be used for? What are you trying to make?

[Spoil9]

Good AVR Tutorial on Running TX433 and RX433 RF modules with AVR microcontrollers
http://winavr.scienceprog.com/example-avr-projects/running-tx433-and-rx433-rf-modules-with-avr-microcontrollers.html
http://www.sparkfun.com/datasheets/RF/KLP_Walkthrough.pdf
http://narobo.com/articles/rfmodules.html
http://www.open.com.au/mikem/arduino/VirtualWire.pdf

Wow. Good find. Looks like this will be some good reading tonight when I can sit down and actually concentrate on what I'm reading.

[blackbeard]

Okay, I'll bite. What's this going to be used for? What are you trying to make?

it's to control an arduino powered robot. thing is i only have one arduino and the only other thing i can use is an altera de1 fpga

[awally88]

I would say buy another Arduino the communications stuff is so easy on them, you can probably do it on teh FPGA but for a simple project its probably just as easy to spend $30 on another Arduino


Here is a tutorial for connecting two arduinos together.
http://www.glacialwanderer.com/hobbyrobotics/?p=291

[Spoil9]

i don't really understand whats being transmitted. what input do i need to create any given output? i don't understand what part of it is 2.4 ghtz and what is 434 mhtz.  i also don't really understand what the sample code is doing and so i can't really make my own. anyone know any examples of how it's used by any chance?

My recomendation is that you re-read all 5 links that have been posted. I do not know anything about programming and yet I learned a little just by reading these links.  I will try to answer your questions as I am looking to use these boards in a project of my own and by helping you I will also learn.
What is being transmitted is simply data bits that are being sent to the transmitter. For example, if you have one Arduino board output a digital string of [001 010 011] then that is what the transmitter will transmit. That is also what the receiver should receive and send as an input to the other Arduino board.

So what ever code you want your robot to "see" is the code you should input into  your transmitter.

There is no mention of anything 2.4Ghz here. There are four (4) types of boards here that transmit on different frequencies. You need to be 100% sure which board you got as the receiver for each one has a different VCC requirement. All the transmitters though can take anything from 2-12V it seems. Other than knowing the VCC requirements, it's really not that important for you to know which freq you're using at this stage in your development. (Although others may disagree)

Which sample code are you referring to? Almost every link has a different sample code. Post the code that is confusing you and hopefully someone else can help you cause like I said, I do not know anything about programming yet. From what I read though, it seems a lot of that programming has to do with encoding the data sent as the receiver tends to pick up any signal that is close to the tuned freq which could cause your bot to do things you don't want it to.

Other little things I've picked up from the links posted that I think you should know:
- the antenna pin needs to be connected to a piece of wire that is 30cm long.
- real world range seems to be around 250ft, and not the 500ft that is listed on sparkfuns website.
- TX/ RX each need about 20/30 micro seconds to "warm up". So any data that is sent in that first 20-30 micro seconds may not be received properly.

Post up any other questions you have about these. They seem to be pretty straight forward with the only hard part being the programming if you don't know how to program 

[Spoil9]

I would say buy another Arduino the communications stuff is so easy on them, you can probably do it on teh FPGA but for a simple project its probably just as easy to spend $30 on another Arduino


Here is a tutorial for connecting two arduinos together.
http://www.glacialwanderer.com/hobbyrobotics/?p=291

+1 to this. From those links posted, it seems to be a LOT easier to just buy another Arduino board and use that with your transmitter than anything else.

[blackbeard]

ok i think i found a solution to buying another arduino. i rigged up a schmidtt trigger oscillator using a 74ls14 to generate a square wave meaning my transmitter cost is reduced from about $40 to about $10. one thing i need now is a way to measure frequency with the arduino on the bot. anyone C savy that can help me with sintax?

[blackbeard]

sorry for the double post but asside from the bump i have another question. what kind of antenna should i use for the receiver and transmitter. it seems to have a decent range without one but i imagine it would help

[Razor Concepts]

Use any piece of wire, you can find the correct length in the datasheets.

[Spoil9]

Other little things I've picked up from the links posted that I think you should know:
- the antenna pin needs to be connected to a piece of wire that is 30cm long.
- real world range seems to be around 250ft, and not the 500ft that is listed on sparkfuns website.
- TX/ RX each need about 20/30 micro seconds to "warm up". So any data that is sent in that first 20-30 micro seconds may not be received properly.

I guess reading is lost in some.

[blackbeard]

oh sorry about that. the post is old and i must have forgotten about that part. anyway here's the control circuitry that i'm using for it. basically i made it so the arduino has to receive a frequency 3 times in a row within a certain range to trigger it's function. the controler works by using resistance with with the capacitor to change the frequency at which the shmidtt trigger is triggered. one button causes one frequency, the other causes another and both at the same time also cause a separate frequency. the arduino basicly uses whichever signal it recieves to either select  the left servo, right servo or both at the same time. i intend to ad reverse later but i need more protoboard scraps . anyone who doesn't needs a cheep RC system might want to look into this

[img=http://img687.imageshack.us/img687/6069/dscn7213.th.jpg]

[chelmi]

Nice! I like the way you used frequencies to encode information!

[blackbeard]

thanks. it's allot of trial and error really. it works super well though

[chelmi]

If you've time, post a schematic of your work for future reference (for you and for us).

Chelmi.

[Spoil9]

Similar to FM, nice.

Not to thread jack, but I was wondering if anyone had any experience with using a sequence generator coupled with the TX, and a sequence detector with the RX as a way to encode signals.
I ask this cause I still don't know how to program and this is the stuff that I'm covering in my intro to digital logic design course so I'm trying to relate what I'm learning to real world apps.