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Old Aug 19, 2014, 07:42 AM
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Originally Posted by AljazJelen View Post
Greetings!
I'm sorry if this post is inappropriate. I am student of university in Ljubljana, faculty of Mechanical engineering. 2 years ago I've fallen in love with arduino and made few smaller projects, not even wort mentioning comparing to stuff on RCGroups.
And because I am looking for a new channel, I've decided to start with a Tx-Rx philosophy. My plan is to make a communication between 2 arduinos by using Tx-Rx modules. But since I am a total newbie in RC world, I would like you guys to recommend me few things:
I've read a lot of tutorials about PPM signals and remaking a Tx or Rx modules, but none of them has a theoretical background. I need that to further understand a electrical circuit which is built in modules, so I can analyze it and adapt to it. You have any suggestions where I should start at?

Sorry for may be so inappropriate post and thanks for your time, patience and info!
If you want to make a communication between two Arduino board .. why bother of PPM ?

PPM is needed only in the RC world .. but for data communication you prefer something else.

There are ready module based on CC1101 (433Mhz) .. that allow you to make a bridge between two serial port ... at 6$ each ... is quick and cheap: http://www.ebay.com/itm/HC-11-433Mhz...-/271574771902

If you are looking to be cheaper, and dig more into the bits and bytes ... then you can use any CC2500 module or A7104 ... or NRF24 too.

For NRF24 you can find free libraries that works off shelf on Arduino ... but even taking the power up NRF24 version your range will be relative poor

In my view, unless you like to study how to program RF chips ... I would take a couple of ready made HC-11 ... and use simple serial interface for communicate between two arduinos.

PS: I was forgetting the good Si4432 module, that are very cheap ... you will need to hack your own software for them ... like for the CC2500 and A7104

PPS: Dave1993 is a super expert on the A7104 chip ... but he does keep most of his secrets well hidden
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Old Aug 19, 2014, 09:12 AM
RC beginner
New York
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yes, but at least he gets part number for a7105 right most of the time. haha!

also worth mentioning that, unlike those that need hacking for wireless serial, xbee does it out of the box. no software or hardware needed. does cost a bit more but not much.
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Old Aug 19, 2014, 09:16 AM
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HAJIME!
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Old Aug 19, 2014, 11:16 AM
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Huh such a response! First of all, thanks for taking your time!

Why bother PPM? Well at first I only wanted to drive arduino with Orange RC transmitter. But ideas went out of control :P
So no, I really don't need PPM for communicating with 2 arduinos at all, I had only messed up a lot of things in my mind.
Right now I am only into making a wireless control of one arduino by using another arduino.
Here comes the RFM22 in game. I wanted to buy 2 of them and use both of them as transceiver. So I would be able to transfer data from ground to air and vice-versa.

e_lm_70 sorry, I am kind of new to forums and apologize that I didn't mention you in a hall of legends (as where Dave and Midelic are :P) Thanks for your reply!
Because I want to learn as much a possible, I would not like to simplify my project. Also I would like to use A7105 or CC2500 or any transceiver module, because I will probably need them later on, when the signals will be PPM (for driving another Quad).
You guys have given me tons of information.
Si4432 module seems interesting because it actually uses same library as RFM22B.
As always I've got infitinite questions but I will "dig deeper" by myself first.
Altho there is smth more I'd like to know: for example A7105 and Si4432 modules can be both used to send any type of signal? Or are there any preffered "rules" about them. For example, A7105 is (as it has been said) popular in many RC applications. What's the reason?

Thanks for your time and passion!

Regards,
Aljaz Jelen
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Old Aug 20, 2014, 08:07 AM
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Quote:
Originally Posted by AljazJelen View Post
Huh such a response! First of all, thanks for taking your time!

Why bother PPM? Well at first I only wanted to drive arduino with Orange RC transmitter. But ideas went out of control :P
So no, I really don't need PPM for communicating with 2 arduinos at all, I had only messed up a lot of things in my mind.
Right now I am only into making a wireless control of one arduino by using another arduino.
Here comes the RFM22 in game. I wanted to buy 2 of them and use both of them as transceiver. So I would be able to transfer data from ground to air and vice-versa.

e_lm_70 sorry, I am kind of new to forums and apologize that I didn't mention you in a hall of legends (as where Dave and Midelic are :P) Thanks for your reply!
Because I want to learn as much a possible, I would not like to simplify my project. Also I would like to use A7105 or CC2500 or any transceiver module, because I will probably need them later on, when the signals will be PPM (for driving another Quad).
You guys have given me tons of information.
Si4432 module seems interesting because it actually uses same library as RFM22B.
As always I've got infitinite questions but I will "dig deeper" by myself first.
Altho there is smth more I'd like to know: for example A7105 and Si4432 modules can be both used to send any type of signal? Or are there any preffered "rules" about them. For example, A7105 is (as it has been said) popular in many RC applications. What's the reason?

Thanks for your time and passion!

Regards,
Aljaz Jelen
Related to Si4432 ... I would suggest to look into the OpenLRS project or OpenLRSng ... you will get the "best" sample for a slow transmission but with possibly the longest range.

There is a lot of PPM stuff and configuration stuff that can be skipped out from these project ... just look at the pure code in charge to make the magic over the Si4432/RFM22B modules.

Else ... you can copy directly from this project: http://www.electrodragon.com/w/index...d-Protected%29

A little tips ... if you avoid the channel hopping ... actually once you initialize the transmitter and the receiver ... all you need to do is to pass new data to be transmitted ... and read for incoming data ... that is normally one or two SPI command

In case you change your mind about module ... NRF24 with Mirf libraries it is ultra easy for make communication using arduinos ... I made also a 2.4G spectrum analyzer on KK2.0 (that has LCD display) using this library .. in really few minutes of coding (ups more then coding was copy paste , a mosaic code )
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Old Aug 21, 2014, 11:48 AM
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e_lm_70 thanks again for your reply! I apologize for my late response, I am a student who tries to work everyday for maximum amount of hours at a company which offers me challenges and I must say that I learn A LOT. Plus I get paid
Well not much, but who doesn't need money 'eh?

Thanks for your explanation. You've mentioned Open LRSing. Is that possible for an example, with Orange LRS module?
I assume LRS stands for "Long range system". That means it is noob friendly, but does the same job as any other module (A7105, Si4432,...)?

Regards!
ALjaz Jelen
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Old Aug 21, 2014, 12:04 PM
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Quote:
Originally Posted by AljazJelen View Post
e_lm_70 thanks again for your reply! I apologize for my late response, I am a student who tries to work everyday for maximum amount of hours at a company which offers me challenges and I must say that I learn A LOT. Plus I get paid
Well not much, but who doesn't need money 'eh?

Thanks for your explanation. You've mentioned Open LRSing. Is that possible for an example, with Orange LRS module?
I assume LRS stands for "Long range system". That means it is noob friendly, but does the same job as any other module (A7105, Si4432,...)?

Regards!
ALjaz Jelen
Yes LRS stand for Long RS
Yes Orange LRS is based on Open LRS and can be flash with OpenLRSng

A7105 , like Si4432 and CC2500 , NRF24L01 ... are all similar RF chip ... but Si4432 is designed for 433Mhz .. while all the other are designed for 2.4GHz .. each of them speak its dialect and does its RF modulation-demodulation

I was forgetting one alternative way that is beloved by Dave1993 ... use plain simple 433Mhz modules: like this for 1.1$ http://www.ebay.com/itm/1pcs-x-Recei...-/181308047424 ... 1 module is a transmitter and one is a receiver ... they work with 1 bit streaming ... there are some simple arduino libraries for properly encode and time the stream of bits ... that allow a simple uni-directional transmission ... this is the bare minimum.

In theory a PPM signal could be send over this module ... and eventually can be used as it is on the other side too ...
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Old Aug 22, 2014, 12:24 PM
RC beginner
New York
Joined Oct 2008
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new tiny ppm version

worth mentioning that i can supply t85 chip now instead of t13 so midelic code can be flashed. fortunately my original code runs unmodified not only on t13 and t85 but also m8, t25, t45, t24, t44, t84, and mega8515. a few others too but these are the only ones tested so far. a big advantage to programming in assembler and not possible with arduino or other c based toolset.

as a result of feedback last weekend from a couple friends who have been using the 8ch program a couple bugs discovered and new photos attached to post #3. an even simpler and easier to build circuit developed for the stm32 quad fc project (http://www.rcgroups.com/forums/showthread.php?t=2222027) due to getting 3.3v direct from the fc. more info on page one.

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Old Aug 22, 2014, 01:32 PM
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Interesting.So now you like take 3.3V from gy-521 cap.
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Old Aug 22, 2014, 04:55 PM
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New York
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yes. off the big one because the little ones tend to float away on the soldering iron. in the case of gy86 everything is available right on the edge pins. as of last weekend instead of plug-in ive started wiring the imus directly onto the fc which is a much neater solution. they are so cheap and taking 3v off the imu is specially simplified.

also note that the rx cap has been eliminated. tests show either the one on the 7105 module, the one on the fc, or the one on the imu is enough for suppression. triple bypass.

more of those wunnerful pics everybody (or at least me) loves when i get back mundy.
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Old Aug 26, 2014, 05:30 PM
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New York
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some photos and info have been added to post #1 showing how to use smd ldo regulator instead of diode for the 7105. this was prompted by applications involving voltages that might be available other than from 1s lipo. as mentioned it does still work for that. also lower levels like 3.3v from a flight controller so more flexible than the diode and the same module can be used in different circuits.

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Last edited by dave1993; Aug 26, 2014 at 05:47 PM.
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