Author Topic: Using inAir modules with Raspberry Pi  (Read 2155 times)

modtro2

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Using inAir modules with Raspberry Pi
« on: October 08, 2015, 05:19:47 PM »
An interesting project for using the inAir (inAir4, inAir9 or inAir9B) modules with the Raspberry Pi and Python is located here:
https://github.com/mayeranalytics/pySX127x

mayer

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Re: Using inAir modules with Raspberry Pi
« Reply #1 on: October 08, 2015, 11:45:50 PM »
Thanks for mentioning my little project  :-)

I am totally puzzled right now why I can only transmit over very short distances.
The varying pin assignments on different Raspberry versions are sorted out. And I have a regulated power source. But still no luck with transmitting. My Spectran HF4040 doesn't measure any significant field strength either (see the attached screenshot).
When I switch off implicit header and CRC the receiver picks up data from somewhere else, so that part seems to work. But the TX looks bleak - no power?!

Update: Apparently I'm not the only one with this problem: https://developer.mbed.org/questions/61132/Is-this-library-compatible-with-inAir9B/
« Last Edit: October 11, 2015, 09:42:10 PM by mayer »

modtro2

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Re: Using inAir modules with Raspberry Pi
« Reply #2 on: October 12, 2015, 11:01:18 PM »
Hi, these modules definitely work. I would love to help you get your sample Raspberry Pi project working, it looks great! And I am sure it will help other. I can send you free replacement modules if you think your modules might be faulty(with condition you keep your project open source, and allow me to link to it). Please note following:
  • The software for the SX1276/8 chips are quite complicated. It is very likely it might be a software bug.
  • You mentioned you had pin assignment trouble. You might have damaged your inAir module? Configuring a RPi port as output that is connected to an output pin of the inAir module can damage the inAir module. This will mean you have 2 outputs driving each other.
  • I think you are using the inAir9B modules? They use the PA_BOOST output of the SX1276 chip, and NOT the regular RFO_HF output. This requires different software than that used for the standard SX1276 drivers. If you use the standard drivers that configure the chip to use the RFO_HF output, you will see the condition you are seeing, with a very, very weak output signal. Seeing that the chip will output to the RFO_HF pin that has nothing connected to it!

If you want to make sure, can send you a replacement, and if your module was faulty, you don't have to pay for it. Please note that for
« Last Edit: October 12, 2015, 11:06:53 PM by modtro2 »

mayer

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Re: Using inAir modules with Raspberry Pi
« Reply #3 on: October 13, 2015, 06:55:00 PM »
Oh, it's the PA_BOOST?! Yes of course... I think I was looking at the inAir9 schematic all that time instead of the inAir9B.
It works beautifully now.
Thanks!