FlightAware Stick


#1

Got the stick and tried it on a p2 and would work for a few minutes. Reconnected RTL and rebooted all was well. I got a new pi3 and behaved the same way.

Any ideas or might this be defective?

Thanks


#2

You didn’t say what failed. But it’s probably a power problem.


#3

The Pi responds to the FA site, but does not transmit data.

How would I tell it is a power thing? The only thing on the Pi is the FA stick.


#4

On the pi there is a red LED. Does it stay on solid or does it blink? Blinking means it is not getting enough power.

How are you powering your pi?


#5

Powered by a dedicated power supply.

The red light is steady on.

Thanks.


#6

There is one good way of being sure you don’t have power problems – measuring the DC voltage at the Pi, GPIO pins 2 and 6, with a good, calibrated digital voltmeter (DVM). If it reads 4.8 Volts or higher (well, up to around 5.1 Volts), you’ve got good power. Below 4.7 Volts is suspect.

“But the wall wart I’m using says it delivers 5 Volts at 2 Amps!”

Yeah, and I’m the tooth fairy. What’s the DVM say?

“But I’m using a USB cable I paid a lot of money for!”

So? I test USB cables under a 500 mA load (a Pi 3 with the Flightaware SDR draws around 650 mA with HDMI powered off). I’ve tested USB cables that drop 0.6 Volts with that 500 mA load. And when I find a USB cable that has a voltage drop like that, I cut it into pieces and throw the pieces away so it won’t fool me or anybody else.

Let’s say your “5 Volt 2 Amp” no-name wall wart actually puts out 4.7 Volts under a 500 mA load. Your USB cable drops 0.6 Volts under a 500 mA load. So, your Pi gets 4.7 Volts from the wall wart (already on the low side and quite iffy) minus 0.6 Volts for the cable, for 4.1 Volts or less, and that isn’t going to work. Not reliably anyway.

Note that some wall warts are rated at 5.2 Volts, which is at the high end of the USB specification. This is fine and makes up for the voltage drop of a typical cheezy USB cable.

The power supply sections on the Pi 2 and the Pi 3 are better than on the earlier Pis, but you still have to feed the beast a good, stable voltage.

Hint: a good DVM costs more than a six pack of beer. A DVM with calibration you can trust costs even more. It’s worth it.

bob k6rtm


#7

Any suggestions on a make/model/brand of high-quality power supply?


#8

For wall warts, the genuine Apple ones for newer iPads and iPhones are good. Also, the 5 Volt supplies sold by Adafruit and Sparkfun are good.

No, Adafruit has a power supply that is great for the Pi.

The Adafruit 5 Volt 2.4 Amp supply (adafruit.com/products/1995) is made for the Pi, complete with a good cable and micro USB connector. It’s a universal switcher, certified over 100 - 240 Volts 50 or 60 cycles, so it should work just as well on the West coast of Japan and the West Coast of Australia. This is a bargain at $8.

Adafruit’s USB Charger Doctor (adafruit.com/products/1852) is a handy gadget to get an idea of what’s going on as far as USB device load is concerned. The voltmeter isn’t as accurate as my Fluke 87V, but its errors are predictable.

bob k6rtm


#9

I’ve got a couple of Drok units from Amazon that show USB voltage and current and have come in helpful. Search for “DROK USB 2.0 Digital Multimeter” and select the LED display version. Currently $10.99 with free shipping, they’re a little more expensive than the Adafruit Charge Doctor but I’ve been happy with them.


#10

In another thread I highly recommended the Adafruit 5V 2.4A supply adafruit.com/products/1995

It has a good quality cable and the required micro USB cable for the Pi. It’s certified for 100 - 240V at 50/60 cycles, so it should work just about anyplace on the planet, from the West Coast of Japan (around 90 Volts, 50 cycles) to the West Coast of Australia (260 Volts 60 Cycles).

$8

Adafruit does good stuff. I trust them.

bob k6rtm


#11

Here is another route you could take:

http://discussions.flightaware.com/post189322.html#p189322


#12

You mean that Harbor Freight freebie won’t cut it? :slight_smile: :wink:
Glad to see you back


#13

The Canakit RasPi psu’s on amazon are also not terrible. Realisitcally - only stays over 5v up until 1a load, but at 2a pushes 4.75v which should be well past sufficient unless you’re trying to really test the limits of your little board.

I’ve also got one of those little DROK usb multimeters. I like it. Actually have it semi-permanently mounted in my setup. Seems fairly accurate. Reads 5.07 under load for my rig whereas an expensive-as-hell Fluke I borrowed from work reads 5.05 at the GPIO pins. Calling that “close enough”

**Also, my power supply rig is a little, uh, lets say “adventurous”
**
I’m feeding a 50w 12v-5v buck with a 5a 12v switching PSU, and tapping the 5v out with a usb header-> usb-a female cable to feed the meter and the pi and another cable to feed the powered hub.

This is mostly a holdover from before the prostick when I needed a 12v power source for an LNA. Sure, I could just use a dedicated 5v psu at this point, but this setup is reliable, the components are fairly inexpensive (the multimeter is the most expensive part of the PS chain at this point) and most importantly, it looks kind of cool!

Anyway - power problems were a huge headache for me at first! The first Pi 2 I had featured a defective, very aggressive brownout detector and if the pi didn’t have at least 5.2v it got very cranky. Further, the system would fail to boot at all with a dongle connected, which lead me to use a powered hub. I can’t reccomend the powered hub strongly enough. When I upgraded to a higher-quality powered hub, USB disconnects completely stopped, and my system runs pretty reliably - considering all the weird mods I’ve shoved into the system at this point. (e.g. that little OLED)


#14

I thought Australia cut down to 230V, from 240V, in the 2000s. Also, they have always been 50hz.