Raspberry disables SSH in Raspbian PIXEL

This is likely to mess up some headless setups : raspberrypi.org have disabled SSH in Raspbian PIXEL .

I have headless Pi’s in use as RTL-SDR server and LoRaWan single channel gateway. One of those was unreachable after updating the OS.

The solution is “If you want to enable SSH, all you need to do is to put a file called ssh in the /boot/ directory.“. And with “/boot/ directory.” they mean the root of the SD card.

Detecing LoRaWan traffic with SDR-RTL

RTL-SDR is a Software Defined Radio using a cheap DVB-T receiver with a chip from Realtek (RTL).

It can tune to 868 MHz and show activity, which is really handy when you are debugging a LoRa node and need to figure out if it is actually transmitting anything.

I bought the receiver from van Dijken Electronica at their stand at the VERON fleamarket for about 25 euro. It plugs into USB or a raspberry pi and the software is free (as in beer). I use SDR# from Airspy.

This is a couple of minutes traffic from a LoRa node building meetup.
The top graph is the current spectrum around 868 MHz, the lower graph is the history. The fuzzy red rectangles are spread spectrum LoRa transmissions.


PoE Pi : Powering a Raspberry Pi with Power over Ethernet

Power over Ethernet (PoE) is a standard for powering devices over an ethernet cable. Aside from the IEEE 802.3af standard (description) there are other ways of powering devices over ethernet cables.

Shopping on internet shows two different PoE solutions, the cheap (and slightly sloppy and maybe dangerous) way is to use unused pairs in the Cat 5 cable and use a passive injector and splitter. The problem with that solution is the dissipation and loss in the network cable at higher powers. The nicer and safer solution is the official IEEE 802.3af solution that I wanted, and I wanted this to work with thin 2-pair Cat 5 cable. Regular Cat5 cable has 4 pairs. I’ll only be using the IEEE 802.3af standard here.

I bought a (second hand and very loud) Cisco Home Office PoE switch to try this all out.


2 Pair Cat-5


I bought a PoE splitter from Aliexpress

IMG_20160515_105601The PoE splitter was fairly cheap (about 7 euro) and there were some doubts if this was actually an active splitter. The sticker on the back states IEEE802.3af compatibility.

IMG_20160515_105620The insides seems legit,an actual PoE controller chip, isolating transformer and Ethernet transformer. The parts used look like the application note with one difference : the application note describes a 10/100/100 MB/s solution with 4 wire pairs, this splitter only supports 2 pairs.


The track clearance is not great though. And there is something going on with the connections between two cable pairs but this configuration seems to be used in other setups as well ( figure 4, figure 1.1 ).


These PoE splitters deliver 12 V. The raspberry Pi needs 5 V on the micro USB port. I’ll need to convert it to 5 V.

Aliexpress and other sites sell step down converters. I bought these, trimmed it to 5 V. and fixated the pot with nail polish.


I sacrificed a USB cable, added a barrel jack and hotsnotted it al in place.



Success ! The setup works with RTL-SDR on a Raspberry Pi.


Philips changes support for 3rd party lamps from Hue, twice.

It seems a firmware update for the Hue bridge and Hue bridge 2 has removed compatibility to 3rd party lamps, that version of the firmware will only work with “Friends of Hue” lamps and no longer support generic Zigbee Light Link lamps.

There was a lot of backlash on this as it can make existing, working, setups useless and raised questions about Philips still effectively being a  member of the  TCLA and if Hue bridges are still Zigbee complaint ?

So, Philips have announced they will (or have) reverse(d) the update on twitter and on meethue.

One sore point seems to remain : Apple HomeKit certification apparently not only applies to the Hue bridge but also to the lamps connected to the Hue Bridge :

Before the 1.11 software update, a bug in the Philips Hue system allowed some non-Apple HomeKit certified lights to work with Apple HomeKit. Our 1.11 software update removed the bug with the result that non-Apple HomeKit certified lights no longer work with Apple HomeKit. This remains the case.

(from meethue). Welcome to the long arm of Apple‘s Walled Garden.



The discovery and confirmation of the update that removed support :
iPhone-Ticker : http://www.iphone-ticker.de/firmware-update-fuer-philips-hue-verhindert-das-einbinden-von-osram-lightify-90450/
Meethue on Twitter : https://twitter.com/tweethue/status/674248181425774592

The announcement of the reversal :
Meethue : http://www2.meethue.com/en-us/update
Twitter : https://twitter.com/tweethue/status/677597933638955008