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From: The Natural Philosopher <tnp@invalid.invalid>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: My question isn't about the fault, its about how to find it.
Date: Tue, 17 Sep 2024 10:37:51 +0100
Organization: A little, after lunch
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On 16/09/2024 21:19, druck wrote:
> On 14/09/2024 19:32, The Natural Philosopher wrote:
>> [   15.888471] brcmfmac: brcmf_cfg80211_set_power_mgmt: power save 
>> enabled
> 
> You may find it is slightly more reliable with power saving disabled.
> 
I have done this. I think it is more stable. It is more appropriate in a 
server anyway


> To disable temporarily use:-
> 
> sudo /sbin/iw dev wlan0 set power_save off
> 
> To make persistent create a file called 
> /etc/udev/rules.d/71-wifi_power_save_off.rules containing the line:-
> 
I used nmcli I think...yes. I have recorded everything I have done on 
this implementation in case I have to do it again.

sudo nmcli c modify [SSID]  802-11-wireless.powersave 2

I had to do it for the other  SSID as well.

I made a decision - as with systemd,- that in NetworkManager was the 
'supported' way to do stuff, I might as well [learn to]  use it.

I am less interested in learning the more recondite areas of the distro, 
than achieving a stable platform on which to build an application.

> SUBSYSTEM=="net", ACTION=="add", DRIVERS=="brcmfmac", KERNEL=="wlan0", 
> RUN="/sbin/iw dev wlan0 set power_save off"
> 
> ---druck

I am not saying 'solved' BUT since using the bigger power supply, it 
hasn't *dropped* at all, however there are still the odd reconnects that 
occasionally  take too long...on one wifi point. Oddly I have two now 
configured and after retrying the first one a few times it decided to 
try the one literally inches away and has been solid on that one ever 
since.

And interesting discovery was that the configuration of a static address 
applies to one SSID only - a 'connection'  in Network Manager parlance - 
not to the *interface* wlan0..

Which is why I thought it had bricked when I changed wifi access points 
on the fly. The next time I did that I realised it was now back on 
DHCP...and was available on a different IP address...

Anyway the final conclusions seem to be :

1. The ZERO 2W is hungrier for electrons than the old ZERO W.
2. The symptoms of starvation are evident first in the WiFi hardware. 
The CPU and nearly everything else is fed from 3.3V, 1.8V and 1.3V 
downconverted supplies. No documentation showing what voltage was used 
by the WiFi chip exists that I could find.
3. On at least my model, whilst the name of the company may have 
changed, the old Broadcomm wifi chip and driver is still used.
4. Apart from having to use journalctl, it is unusually not possible to 
blame systemd for these issues.
5. Whilst a chinesium USB source *may* be able to deliver the quoted 
current, it is not necessarily  able to deliver it in a noise free or 
voltage-retaining fashion.

I never got round to putting a meter or a scope on the thing - it's a 
bit awkward especially with a 'hat' on.

Interestingly the Pi PICO W uses a chip that works down to 3V.

Now I have achieved stability, the unit will go to a different location 
to further development where it will naturally connect to the original 
POS wifi point.

But I now have a microwave with a burnt out magnetron to fix...

Sigh.

-- 
The lifetime of any political organisation is about three years before 
its been subverted by the people it tried to warn you about.

Anon.