The hard RAK831 cafe part 2

(Phil Wilko) #21

Thanks @GryKyo. A fantastic post on your Gateway too. It sounds like you have had little problems once the Gateway has been installed, which is great to hear.
It does highlight the differences between climates though, here in Perth Australia we regularly hit 40C for days at a time during the Summer so I had better have the internal temperature monitored, fans installed and perhaps a max temp shutoff function!

(Gry Kyo) #22

OK, so once again I declare that I am a mech engineer, not a programmer but you could run a small python or similar on your linux box, I guess a Pi.
From command line:
/opt/vc/bin/vcgencmd measure_temp

will return your Pi’s CPU temperature which can be used to operate a fan or even a stand alone fan/temp controller in the installation. Only issue with this is remoteness and no closed-loop I guess. I have some projects which use cURL to push messages via Pushbullet to mobile devices and Chrome for alarms and warnings, very handy for remote devices.

With regard to the packet forwarder it has a live log and a SSH terminal so very suitable for remote control/monitor of your gateway and seems very robust in the short while I am using it.



Antenna included with RAK831 (868MHz) board

This is a photo of the inside of the antenna (RP-SMA) included with my RAK831 (868MHz) board.
The antenna rattled when I picked it up. I opened it to see what was wrong and found that the coil had come loose, which I was able to fix.


@jezd The hard RAK831 cafe part 1

who supplies the tall case?

ModMyPi Cyntech Modular Cases for RPi 2/3



Recent versions of this case have light pipes on both sides of the micro-SD slot so they are suitable for both RPi 2 and RPi 3. The brochure shows the older RPi 2 case which has light pipes for RPi 2 only (RPi 3 does fit in the older version but you would not see the LEDs).

(Laurens Slats) #25

During The Things Conference we are organizing a workshop on how to build a gateway, using the RAK831.

If you have some experience and want to help out with this workshop on February 1st, please send me a pm.


See ‘RAK RPi Converter Board apparently has bugs/lacks in wiring of GPS module and antenna’ in topic: RAK831’s and its Pi converter board modifications


I replaced the RP-SMA antenna included with RAK831 with this 868MHz SMA antenna (standard quarter wavelength whip).
(They show pictures of different antennas, the first picture - the antenna with single groove on top - is correct.)

In a simple test with a node about 2m distance from the gateway (node with same above antenna):
RSSI jumped from -45 to -25 and SNR stayed similar around 9 to 10. (Have not done any further testing.)

The included whip antenna (rated by RAKWireless as 1GHz) does not perform very well in the comparison. Replacing it with a better antenna (like the above) will get better results from the gateway.

_(I replaced the RP-SMA connector on the RAK831 with SMA so it doesn’t need a converter for SMA antenna and prevents (minor) converter losses.)


@laurens Are you talking about something like that ?

  • Push button on GPIO17 to be able to shutdown PI Locally
  • FTDI connector to be able to take hand on PI console when in enclosure (lost network or whatever, no more need to get all off the enclosure and connect HDMI cable to see what’s going on)
  • Footprint for excellent Murata OKI-78SR-5 DC/DC 5V
  • Footprint for RASK831 concentrator (main goal) with pressfit connector for solderless PI Zero
  • I2C connectors to be able to add internal/external sensors such as BME280, SI7021 or HTU21D or excellent 2.4" OLED
  • Power with terminal block press fit
  • 3 visual WS2812B Led (wifi and network state, packet state, …)
  • Easy to build and solder, 0805 or PTH components
  • Holes to fix board on enclosure or other support
  • Nice Hammond 1591 enclosure size (different colors)
  • 2 versions, the other is for outdoor enclosure even smaller

Currently writing documentation, monitoring scripts, RO filesystem to add robustness and even a procedure to have full lorawan server installed for local use :wink:
Also new 1.3 revision on the go to be able to put RAK831 on the other side of this PCB so we can see RAK Led (and fix silk error of RAK831 pinout)

Mounted this one in a hurry for a customer, works fine, but RAK831 is becoming hot in enclosure, need to check that point


Some pictures of my RPi 2 + RAK831 gateway:

Not in a case yet but keeps it cool.


I see those enclosures popping up but nowhere I can find what material its made of, was thinking maybe a rak831 enclosure ?



(Luz) #32

As a fan of small OpenWrt/LEDE Linux thingies, I built a RAK831 based gateway based on Omega2S and created a LEDE build for it.

If anyone is interested:

  • here’s the github project with README explaining how to build the LEDE based TTN-gateway firmware from scratch. The firmware is not very elaborate yet, but it works out of the box registering a “legacy forwarder” based gateway with a EUI based on the Omega’s MAC address.
  • Here’s a PCB I had fabbed at oshpark which hosts a Omega2S, a ethernet jack and power regulators to run the entire GW via PPoE (network and power over the ethernet cable). It fits together with the RAK831 into a watertight IP65 case from Hammond (1554EGY).

some pictures:

The parts

Assembled PCB

On the roof


wow… respect :sunglasses:

* googling for 'omega2s :grinning:

(Jac Kersing) #34

:slight_smile: Very nice!

It looks like you are using the antenna shipped with the RAK board. If so, I suggest you look for another one with better performance. If you want to use a whip antenna, if I’m not mistaken PyCom uses RP-SMA antennas for the LoPy. (@jmarcelino might be able to confirm)


Very nice! :slightly_smiling_face:

What kind of flat cable are you using between gateway and the house?
What about the temperature inside the case?

(Cherget) #36

Where can we get Omega2s modules?


(Luz) #38

Thanks for the hint - yes, in a first step I am using the antenna that came with the RAK, but I already saw posts in this thread saying there’s room for optimisation…

I’m a newbie regarding LoRA and antennas, much to learn here… My experience is with building small LEDE-based thingies, so I thought I’d start with that, making a HW/SW platform first. I very much like the way LEDE can reproducibly generate a complete TTN GW Linux firmware into a 6M image by just typing make on the command line (almost) :wink:

(Luz) #39

The cable you see on the photo is a very bad ultra-cheap cable (that violates every possible ethernet cable specs) I used for first tests, because it is so flat that it goes through the sealing of the case. In the meantime a proper ethernet cable goes through a sealed grommet in the case.

About temperature - the max power both Omega2 and RAK consume together is about 2W, the average usually less than that. That should be easy to dissipate through the plastic box. The max operating temperature of the RAK is 85°C. We get 35°C max here in Zürich, so I think there’s enough margin even in direct sunlight in summer (for a white box with free air circulation around it).

(Gry Kyo) #40

Interesting that you talk of temperature here, only 5 minutes ago I had a look at the CPU temperature of my Raspberry Pi (in a spacious plastic enclosure with the RAK831) on the roof of my house. We are feeling the first cold snap of winter here in Ireland, between 0° and -5°C so I am interested to see how cold it gets in the enclosure.

root@xxxxxxx:/opt/ttn-gateway# /opt/vc/bin/vcgencmd measure_temp
with the current outside air temperature at 1°C

It never gets much above 28°C here in summer so I should check back then for a maximum.