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Mar 01, 2014, 11:30 AM
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Cheap & Easy - DIY openLRS/openLRSng - RX & TX modules

How to build up a openLRS / OpenLRSng DIY module:

Shopping parts:
2.8$ Pro Mini board :
3.6$ Si4432 module :

3.3v regulator :
Or DIY 3.3 regulator ->

PNP adapter board :

Note: I put the first link from eBay, check every time, since the best offer from eBay is often from a different seller. So I'm not promoting any eBay guy, just putting the first link as example


Here is my first prototype of DIY RX ... using an Arduino Nano board , mainly because this was a test and the Nano board I will reuse from a different test and I will plug the RF module to a Pro Mini in a more permanent way ...
Last edited by e_lm_70; Mar 02, 2014 at 04:26 PM.
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Mar 01, 2014, 11:30 AM
Registered User


Note .. this is V0 for me ... I will go soon for a different wiring .. as soon as I will get the SOP adapters, that will make life more easier for build this module:


Here is the way to connect the Si4432 for make it compatible with OpenLRSng:
Select board type #5 (that is the most easy one in my view, that's why this is how to clone the 4ch/6ch DTF UHF, that is open code and open hardware)

Thanks to Midelic for the schema (note this diagram is only valid as RX , not as TX)

SDN to ground (could be use as additional switch, but is a waste of soldering time)
NSEL to PD4 (D4)
NIRQ to PD2 (D2)
SDO to PB4 (D12)
SDI to PB3 (D11)
SCK to PB5 (D13)

PPM on PB1 (D9)
RSSI on PD3 (D3)
Other output ports:
SDA (A4)
SCL (A5)

Red Led -> D6
Green Led -> D5

On the Rfm22b ... they short
But this is not needed on Si4432 (there is no TXant and no RXant on Si4432 and GPIO0 and GPIO1 can be left non connected


SDN, NSEL, etc are the name of the pin in the Si4432 module
D2 D3, ... A0, A1, ... are the name of the pin in the arduino nano/pro mini mdoules

So these names are written on the boards

PB1, PD1, etc are the pin name of the atmega chip for atmel, but Arduino decided to rename these pin


About TX, I still did not test it out ... but few notes are important:
The general approach used above is valid, but for people that want to use directly OpenLRNng firmware, some of the PIN between TX and RX are different, mainly:

PPM_IN is D8 (note: RX use D9 as PPM_OUT)

BUZZER_ACT is A5 (from i2c interface)
Bind buttons is on A4 (so an external switch for A4 need to be used, a bit odd .. HW i2c interface due to this is totally unusable at TX level)

Following is the TX diagram:
Last edited by e_lm_70; Mar 03, 2014 at 04:51 PM.
Mar 01, 2014, 12:32 PM
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SO far the test has been following:

Using a HobbyKing RX OpenLRS orange, converted into TX via firmware openLRSng update.

Connect the TX to the PC GUI (openLRSng GUI)

Power up the DIY RX

On the GUI, the RX is visible, and it is possible to configure the different output ports ... so ... RX is working and it is happily communicating to the TX

Range test will follow later ... in the DIY process I manage to destroy my 1W Orange TX OpenLRS ... damned cabling needed for make OpenLRSng GUI to work
Mar 01, 2014, 12:53 PM
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midelic's Avatar
Nice.I'll make soon a nice diagram...with promini.
Mar 01, 2014, 01:21 PM
Entropy is happening!
Jim.Thompson's Avatar
Peta ?
Mar 01, 2014, 01:33 PM
Registered User
Originally Posted by Jim.Thompson
Peta ?
Mar 01, 2014, 01:37 PM
Entropy is happening!
Jim.Thompson's Avatar
Please explain the acronyms!
Mar 01, 2014, 01:52 PM
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midelic's Avatar
And I though that "e" killed some!
Mar 01, 2014, 03:01 PM
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Originally Posted by Jim.Thompson
Please explain the acronyms!
Which ?

Peta ? ... I did not type Peta

Originally Posted by midelic
And I though that "e" killed some!
What ?

Mar 01, 2014, 03:10 PM
Registered User
When I will get the pin adapter from china, I will make a nice video about how to build up these modules

So I guess everybody could make DIY if they wish to
Mar 01, 2014, 09:05 PM
Registered User
Suggested project name: YAARCS! - Yet Another Analog Radio Control System!
Mar 01, 2014, 09:13 PM
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midelic's Avatar
It is not another ...the project exists already...only emphasize on cheap and DIY....
Mar 01, 2014, 09:18 PM
Registered User
And wait Sketch If you can write program for a AVR ,( is not Arduino ) ,i think price is cheapbest . two Atmega8
Mar 01, 2014, 10:11 PM
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midelic's Avatar
As promised .... check diagram see if ok..

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