Sral's Aquarium and Reef-Pi Build

Sral · Jul 11, 2022

Alright, I celebrated a little bit too early.

After yesterdays post I tried powering off the PI, but the connection didn't work at that time. My phone got the Pages title (Reef-PI) and displayed a white screen with "loading...". Nothing more. Afterwards my PC couldn't even ping the PI anymore.

Same today, couldn't find the PI and disconnected the Ethernet cable. Reconnected it and the PI showed up. As I am writing this however, the PI vanished again. And now reappeared.

I'm absolutely confused, as even reconnecting the capacitor and turning up the voltage wont help right now

That saying however, the PI showing up aftr reconnecting the Ethernet cable indicates that the problem lies with the Ethernet Hub and not the PI itself.

Ranjib · Jul 11, 2022

i have a central prometheus server+grafana setup that lets me see all these details. I run node exporter on all pi and that gives prometheus all the system level details from pi that i can see through grafana. In situations like this, it helps me understand system details during issues

Sral · Jul 11, 2022

Ranjib said:
i have a central prometheus server+grafana setup that lets me see all these details. I run node exporter on all pi and that gives prometheus all the system level details from pi that i can see through grafana. In situations like this, it helps me understand system details during issues

So that's basically a service that discovers TCP/IP targets and queries data from them if available.
That data is stored in a database, which you then visualize using Grafana. Is that about it ?

If so, you would install the prometheus node exporter on the PI and run that as a service I guess, but how much would that help if the TCP interface is unstable, like it looks in my case ?

Ranjib · Jul 12, 2022

prometheus is the central time series database, and installed separately on x86 machine (preferably). I use a mini pc to run prometheus+grafana. Only node-exporter is installed on pi which provides all those tcp stats through an http end point. The central prometheus server is configured to scrape the data from node exporter (from on or many pi's). This is the same mechanism used to for reef-pi integration (reef-pi exposed all metrics under an endpoint, which prometheus central server then scrapes) . Grafana can be installed in another machine, but i colocate on the same mini pc as the promethues, and configured to talk to the prometheus server as data source. Grafana provides the visualization of those time series data.
This stack is very similar to a large web company (cough cough)....that is retrofitted to work on home setup

. Its bit complex, but its as (if not more than paid solutions) advance and powerful mertics/telemetry stack as you can get (through FOSS).

Sral · Jul 12, 2022

So would that node exporter still work in times where I have no connection and then resend everything when the connection comes back online, after a reboot for example ?

Ranjib · Jul 12, 2022

Sral said:
So would that node exporter still work in times where I have no connection and then resend everything when the connection comes back online, after a reboot for example ?

i dont think so.. but prometheus will poll node exporter every 10s, so you get to see what happened leading up to the issue,,, frequencey and span of the connectivity issue etc..through absence of data. the fact theres constant tcp connection happening, also adds to some benefits

Sral · Jul 12, 2022

Okay, I tried a few things, but the problem continues.
Tried the capacitor closer to the Power supply and only connected the Pi after I was sure that the capacitor was charged. I read somewhere that a slowly ramping supply voltage can cause boot problems. Didn’t help though. The IP shows up on an “arp -a” on windows cmd, but even just pinging leads to the last 3 of 4 pings to time out. Afterwards the IP is gone.

i tried with the working power supply again and the IP only showed up after I power cycled the Ethernet Adapter. So I’m thinking that the problem lies there. Maybe the Adapter doesn’t get enough power when I channel it through the HAT and the pins, it’s disturbed by the 400kHz ripple or some earthing problem. Could be that my circuit loads up and the Ethernet connects two different potentials.

I’ll try a few things, firstly to earth my circuit and then to supply the power either through the USB power port or to the Ethernet Adapter itself.

Ranjib · Jul 12, 2022

Sral said:
Okay, I tried a few things, but the problem continues.
Tried the capacitor closer to the Power supply and only connected the Pi after I was sure that the capacitor was charged. I read somewhere that a slowly ramping supply voltage can cause boot problems. Didn’t help though. The IP shows up on an “arp -a” on windows cmd, but even just pinging leads to the last 3 of 4 pings to time out. Afterwards the IP is gone.

i tried with the working power supply again and the IP only showed up after I power cycled the Ethernet Adapter. So I’m thinking that the problem lies there. Maybe the Adapter doesn’t get enough power when I channel it through the HAT and the pins, it’s disturbed by the 400kHz ripple or some earthing problem. Could be that my circuit loads up and the Ethernet connects two different potentials.

I’ll try a few things, firstly to earth my circuit and then to supply the power either through the USB power port or to the Ethernet Adapter itself.

Pi can only draw above 1A from the usb

Sral · Jul 13, 2022

Ranjib said:
Pi can only draw above 1A from the usb

You mean it can only draw about 1A from the PWR USB port ?
Still, it’s very strange, since supplying it through the PWR USB works, but through the HAT it doesn’t. Even though both sources, the phone charger and the LM2596 module, can supply well over 2A
I’l still Test it, since I’m grasping at straws here -^^
I’ll also measure the ground difference. Would be funny if that was the problem, since I have been advising people to do the same with their pH probes XD

robsworld78 · Jul 13, 2022

What do you think the chances are the wifi adapter just doesn't like your router? I had a laptop the wifi didn't work on so I used a USB adapter, first one I bought was it worked then it didn't so I got a different one and it was smooth sailing.

Ranjib · Jul 13, 2022

Sral said:
You mean it can only draw about 1A from the PWR USB port ?
Still, it’s very strange, since supplying it through the PWR USB works, but through the HAT it doesn’t. Even though both sources, the phone charger and the LM2596 module, can supply well over 2A
I’l still Test it, since I’m grasping at straws here -^^
I’ll also measure the ground difference. Would be funny if that was the problem, since I have been advising people to do the same with their pH probes XD

i mean it can only draw more than 1A from USB port, through GPIO i think it can max draw 1A. So anything thats require above 1A pi power usage mush use micro usb

Sral · Jul 13, 2022

robsworld78 said:
What do you think the chances are the wifi adapter just doesn't like your router? I had a laptop the wifi didn't work on so I used a USB adapter, first one I bought was it worked then it didn't so I got a different one and it was smooth sailing.

Well, it's an Adafruit Ethernet to OTG Adapter, so no WiFi. However it's a good point worth thinking about. I do however believe that's not the issue, since it works when I connect the PI through the OTG PWR to the 2.5A phone charger. IÄll keep it in mind though and will replace this Adapter when I can't advance further through other means.

Ranjib said:
i mean it can only draw more than 1A from USB port, through GPIO i think it can max draw 1A. So anything thats require above 1A pi power usage mush use micro usb

Hmmm, good info. I don't think it draws more than 1A, since the PI itself should stay at 250mA max and the Adapter is rated at something like 280mA idle, so maybe 500mA max. However, you never know how it handles peaks, so it's worth investigating !

Sral · Jul 13, 2022

Alright, thought I had my culprit. Measured about 18V AC between AC earth and circuit ground. When I connect the Ethernet that drops to 17V AC:

However … when I do the same with the Phone charger that works better, the values are 120V AC and 30 C AC (with Ethernet connected)

Sral · Jul 13, 2022

Tried to supply power through the PWR USB. It was not clean, but at least quick. I connected that power connector that's normally on the PI HAT to header cables, fed that into the USB Breakout you see in the box and plugged the USB cable I had used previously into the breakout USB socket. PI showed up after I dis- and reconnected the Ethernet Adapter.

The connection was unstable though.

Sral · Jul 14, 2022

I also tried to connect my circuit's ground to AC earth.

As mentioned earlier, I have ~18V AC between 230V AC Ground and both my circuit's ground and +5V line when supplying power from 230VAC -> 12V3A AC/DC converter -> 5V/3A DC/DC converter. When I connect to AC Earth through a 66k resistor this drops to ~3V AC with 50µA AV. The connection still doesn't stabilize.

When I connect to the 2.5A USB charger, the connection is stable. At least after I force the Ethernet Hub to power off and on again. Connecting to ground in the same way gives a current of 30µA AC.

Next I'll try to supply power through a gutted USB OTG cable to connect the USB OTG PWR port more directly to my DC/DC converter with less resistance and cable involved.

Sral · Jul 15, 2022

Alright, I gutted the USB OTG cable and ... it has incredibly tiny wires. Not sure how that can handle 2A, but it worked together with the 2.5A phone charger XD Didn't improve the situation though, when I connect to the 5V3A DC/DC converters.

Currently I'm thinking that it might be due to the converters. Maybe one of them is broken or not ideal and produces too much ripple or isn't isolated well enough (or similar), which the Ethernet Adapter can't handle. Strangely though the PI doesn't seem to care. Any idea's on how to check whether they are functioning properly ? ^^

Out of frustration I ordered a tiny RT5730 WiFi stick with cable. Set to arrive after the weekend, let's see if that works better ^^

Ranjib · Jul 15, 2022

if the pi is not showing any undervoltage warning, will you still be worried about it?

Sral · Jul 15, 2022

I checked that using:

Code:

dmesg | grep -iC 3 "under"

when I did get a connection. Nothing there, but the fact remains: I only get a stable connection using the 2.5A phone charger, not when I use my 12V/3A AC/DC and 5V/3A DC/DC converters. In both cases I sometimes had to power cycle the Ethernet Adapter to make it work, so it looks like the weakest link.

I'm thinking of adding some bypass capacitors and/or some load resistors to give all power supplies a base load. According to the datasheets they work without load, but you never know ...

I'll also install a timer script that makes an LED blink once a second so I can see whether and when the PI loads and crashed without an Ethernet connection.

I'm currently mostly worried about not progressing past this darn Ethernet issue

Sral · Jul 15, 2022

Alright, installed the blinking test LED. Simply installed a timer to turn it on and off in ReefPi and set it to work all the time, e.g. all entries are "*"

Starts blinking approximately 30-40 seconds after connecting power, both with the phone charger and the DC/DC converters. I do not get a connection at first. Only after un- and replugging the Ethernet Adapter, I get a connection 30-40 seconds later. During which the LED doesn't blink.

So power cycling the Ethernet Adapter actually crashes or power cycles the PI, great

For the phone charger the Page is available and stable after this, for the DC/DC converter the page's name appears, but the connection isn't stable enough to load.

Sooo, I'm going to have to wait for the WiFi Dongle and get back to you when I test that.

oreo54 · Jul 15, 2022

Sral said:
Alright, installed the blinking test LED. Simply installed a timer to turn it on and off in ReefPi and set it to work all the time, e.g. all entries are "*"

Starts blinking approximately 30-40 seconds after connecting power, both with the phone charger and the DC/DC converters. I do not get a connection at first. Only after un- and replugging the Ethernet Adapter, I get a connection 30-40 seconds later. During which the LED doesn't blink.

So power cycling the Ethernet Adapter actually crashes or power cycles the PI, great
For the phone charger the Page is available and stable after this, for the DC/DC converter the page's name appears, but the connection isn't stable enough to load.

Sooo, I'm going to have to wait for the WiFi Dongle and get back to you when I test that.

Man, love reading your stuff but 95% goes right over my head.
One thing though after 20+ years of tinkering with computers when a "part" doesn't work out of the box just get a different part.
I hope the dongle works..
As to your orig ..