[arm-allstar] One of two USB URIs dropping off

Sat Jan 12 21:30:07 EST 2019

Hi,

I use these cheap tiny adjustable DC-DC supplies, just a couple dollars each on eBay, fed with 12-14 VDC. So long as your 5V wires are short and heavy to minimize resistance and hence variation with load to the Pi, you can then adjust the supply up to sufficient voltage (possibly as high as 5.2-5.4 – I should measure...) that you measure 5.0 or 5.1 volts on the test point directly on the Pi PCB. Google for where exactly to measure. There is a poly fuse and maybe other sources of voltage drop on the Pi; hence the need to use a greater than 5V supply, especially on the more power hungry 3B+! This works great! 

My experience was the fixed voltage epoxy potted 12V-5V converters are too low voltage an output when under load, considering the resistive loss of the 3B+ setup.

KC3DRE

Mark G Thomas

I am not sure if the photos will make it:

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> On Jan 12, 2019, at 17:36, Randy Neals via ARM-allstar <arm-allstar at hamvoip.org> wrote:
> 
> Still having one of the URIs stop, but using the "dmesg" command, we are
> seeing low voltage alerts.
> ie: [   13.607990]
> 
> *Under-voltage detected! (0x00050005)*I'm not able to make a trip to the
> repeater site to replace the power supply for a few days.
> So I'll try something else...
> 
> I'm not using WiFi on the Pi.
> According to this thread, turning off WLAN0 results in 142mA lower current.
> If my power supply is weak, perhaps saving 142mA will provide better
> voltage control.
> 
> https://www.raspberrypi.org/forums/viewtopic.php?t=208110.
> 
> ifconfig wlan0 down
> 
> 
> -Randy
> 
> 
> 
> On Fri, Jan 11, 2019 at 9:56 PM "Doug Crompton via ARM-allstar" <
> arm-allstar at hamvoip.org> wrote:
> 
>> Randy,
>> 
>> Being able to power cycle a remote Pi is very important. There are many
>> ways to do that as you know so you have to pick the best one for you.
>> 
>> I think the one radio node per Pi especially if both nodes are running
>> repeaters is a good idea. Management is a lot easier if you use supermon
>> and configure all nodes on one screen. You can instantly see the status of
>> everything and have control of all the connections. I have 13 nodes and
>> servers both local and remote displayed on one supermon screen. Even if you
>> had multiple supermon screens they could be in adjacent tabs on a browser.
>> 
>> 
>> *73 Doug*
>> 
>> *WA3DSP*
>> 
>> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
>> 
>> On Sat, Jan 12, 2019 at 12:45 AM "Randy Neals via ARM-allstar" <
>> arm-allstar at hamvoip.org> wrote:
>> 
>>> I agree. The suppliers on Amazon for those potted dc dc converters change
>>> like the weather.
>>> 
>>> The 3B+ uses an entirely new DC regulator module.
>>> A custom design for the Raspberry Pi.
>>> 
>>> 
>>> I’m thinking of using POE Hats and powering my Pi’s from an Ethernet
>>> switch. If the switch is “Managed”, it also provides a way of turning off
>>> the port and rebooting the Pi.
>>> 
>>> The second gen Pi POE Hat would seem like an elegant solution.
>>> 
>>> I may also revert to a Pi per repeater.
>>> I dislike having multiple Pi’s to admin and multiple firewall port
>>> mappings, but I like reliable nodes better :)
>>> 
>>> https://www.raspberrypi.org/blog/poe-hat-revision/
>>> 
>>> 
>>> 
>>>> On Fri, Jan 11, 2019 at 10:11 PM David McGough <kb4fxc at inttek.net>
>>> wrote:
>>> 
>>>> 
>>>> 
>>>> Hi Randy,
>>>> 
>>>> Okay, yes, looking at the dmesg output, this issue looks power related,
>>>> one way or another. Note below that just after the "under voltage"
>>>> warning, and before the "voltage normalized," the URI(s) aren't happy.
>>>> 
>>>> The micro-USB power connection on the RPi3b+ may be the problem.
>> Another
>>>> factor that we've noticed recently is that some brands of the epoxy
>>> potted
>>>> 5V3A DC-DC converters don't perform as well as others. Frustrating.
>>>> 
>>>> A subtle ground loop, even with the hardware in same chassis, might be
>>> the
>>>> culprit, too.
>>>> 
>>>> 73, David KB4FXC
>>>> 
>>>> 
>>>> 
>>>>> On Fri, 11 Jan 2019, Randy Neals wrote:
>>>>> 
>>>>> Hi David,
>>>>> Thanks for the email...
>>>>> 
>>>>> Usually just one URI stops. It seems to be the first port, my VHF
>>>> repeater.
>>>>> Earlier it seemed like it was alternating with no pattern between
>>>> repeaters.
>>>>> (Thus I wasn't suspecting a bad URI)
>>>>> 
>>>>> No reboot of the system, no hang. Other repeater usually continues to
>>>>> operate.
>>>>> 
>>>>> The repeaters are ICOM FR-5000/FR-6000
>>>>> Both repeater RF modules are in the same metal Icom rack chassis, ie:
>>>> same
>>>>> ground for both repeaters.
>>>>> The Audio and COR/PTT come out on DB25 connector on back of repeater.
>>>>> 1' cable with signal/audio to URI
>>>>> 
>>>>> The repeaters are powered from 12VDC power distribution.
>>>>> 12V power is from a large communications power supply (Switch mode
>> N+1
>>>>> redundant) with battery backup.
>>>>> 
>>>>> The 5V Pi power is a DC to DC converter rated at 3 Amps. 12V from the
>>>> same
>>>>> distribution as repeater. 5V on micro USB to Pi.
>>>>> At first I had a different PS, and swapped early thinking that was
>> the
>>>>> problem.
>>>>> 
>>>>> The Pi is in an aluminum chassis with a tiny fan.
>>>>> It is on a rack shelf above the repeater. The Pi chassis is not
>>> grounded,
>>>>> but it has 2 USB cable, and the power supply cable to the DC DC
>>> converter
>>>>> which may have ground.
>>>>> 
>>>>> Here's dmesg
>>>>> I see several "under voltage" messages. That doesn't seem good.
>>>>> 
>>>>> I rebooted just a few minutes ago. When the URI stops again, I'll run
>>>> dmesg
>>>>> again.
>>>>> 
>>>>> 
>>>>> [    7.215868] sd 0:0:0:0: [sda] Assuming drive cache: write through
>>>>> 
>>>>> [    7.222428]  sda: sda1
>>>>> 
>>>>> [    7.227933] sd 0:0:0:0: [sda] Attached SCSI removable disk
>>>>> 
>>>>> [    8.300598] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps,
>> full-duplex,
>>>> lpa
>>>>> 0xD1E1
>>>>> 
>>>>> [   13.608033] *Under-voltage detected! (0x00050005)*
>>>>> 
>>>>> [   17.229524] retire_capture_urb*: 119 callbacks suppressed*
>>>>> 
>>>>> [   21.938034] Voltage normalised (0x00000000)
>>>>> 
>>>>> [   26.348512] retire_capture_urb*: 18 callbacks suppressed*
>>>> <snip>
>>>> 
>>>> --
>>> Sent from mobile.
>>> _______________________________________________