Micro USB Cable as source for Dump1090 crashes


#1

The last days I was plagued with Dump1090 crashed.
Of course I had the power supply under suspicion and replaced it but it did not fix the problem.
My cheap USB power meter showed me voltages of around 4.6V-4.7V measured at the PI.
This made me think that the micro usb cable could be the source although the cable in use was bought as a cable with low-resistance and of high quality (Yes! Marketing blabla).

This evening I did test at least 8 cables with the Rui Deng UM25C meter and LD25 load. With this combination there is a procedure to determine the resistance of a cable under load.
I did test with a load of about 1000 mAh and to my surprise (or maybe not); the “good” cable had a relative high resistance confirming a voltage drop from 5.2V at the power supply to 4.6V at the micro usb side. In fact most of the cables were crap except one.

I found an unbranded cable, I even don’t know where I did get it from, that performed actually quite good; at the micro usb side I still measured 5.0V.

Lesson learned:

  • Use short micro usb cables
  • High quality claims are not always true
  • Measure the cable yourself

#2

I’ll add one more: use the thickest (wire gauge) USB cable you can find.

Thinner cables may look nice, but they are ‘dogs’.

If one uses thicker cables, ‘short’ does not need to be ‘shortest’.


#3

Just in case this shop ships to you and you are looking for a cable again.
https://www.rasppishop.de/MicroUSB-Kabel-Stecker-offen-fuer-Hutschiene
Then add one of these power supplies:

The 3A version should work as well but hey the price difference wasn’t much and maybe i want to run a second pi off the same supply one day :slight_smile:

What is really sad that they don’t provide pins or solder pads to have a protected power input into the RPi.
Input of power via the pinheader is a bad idea as i understand.


#4

The problem with the cables, and I have some nice thick cables, is that you can not look at the inside without destroying it. I looking at all the cables I have it is deceiving.


#5

At this moment I am buying components to renew my ADSB setup completely.

I have now a good power supply in my shop which I will hookup to my UUGear USB hub. The hub bolts on to the Raspi. The Raspi is powered by the hub through pogo pins and also the USB connection is made through pogo pins (so no USB cable to connect the Raspi and USB hub). The USB hub can be powered via it’s micro usb port or via a JST XH 2.54 2-Pin connector. I will use the JST connector to eliminate the micro usb cables. All components will be mounted on a DIN rail.

The power supply I will be using is a TDK-LAMBDA DRB-50-5-1 with 5V/6A which gives more than enough power for 2-3 Raspi’s. The power supply is not cheap, it is 42 Euro but I am fed up with all the crappy stuff I have been going through.

The MeanWell supplies are also good. I use them in other Raspi projects as well but in this case I decided for rail mount. I use 2 TDK supplies for other purposes and they performing according expectations.

As the say: the weakest link breaks the chain but I never had a closer look at the cable because I thought I was buying and using descent cables … until I started measuring.


#6

As i said the problem is with the fusing, to quote another web page:

A more technical (and of course dangerous) way to power the Pi is directly via the GPIO. It should be noted that, unlike the Micro-USB port, there is no regulation or fuse protection on the GPIO to protect from over-voltage or current spikes.

So if i didn’t have that micro-usb cable which still is of course not as good as a proper connector that doesn’t come loose as easily as micro-usb (actually it’s handled moving the pi around so i shouldn’t complain) i would think about desoldering the micro-usb socket and just solder two wires on there so i still have the fuse and stuff.


#7

There is a certain risk of powering via the GPIO although in a specific setup I use since 2 years for a media player with a open frame meanwell supply it works fine.

Powering through the UUGear hub is a different story because it has it’s own power circuit.

A good power supply like the meanwell or TDK is not supposed to spike or over voltage. Of course there is no 100% guarantee because any technical component can fail.