[Ovmsdev] Modem won't start

Chris van der Meijden chris at arachnon.de
Thu Oct 1 03:48:50 HKT 2020

Background on the PoweringOn issue for me was, that we yesterday had a
complete internet breakdown in our village. A digger cut a fibreglas
cable. 2000 people with no internet was the result ...
We still had DSL sync, but pppOE did not come through anymore.
I also have very poor (2G) connection with my OVMS sim at our house.
So I could think  of a scenario like this:
The car thinks- I am connected to wifi. Great, lets connect to the
server.- Hmmm, I can't reach the server. No DNS resolving.- Lets try
GSM- Hmmm, no connection to my provider- Lets try wifi again- Hmmm, no
And that for 14 hours, every few seconds ...
Well it is pure speculation, but perhaps of some help.
For now the system is completely broken. The system was down, I took it
out of the car and broke the USB connector again ...
I'm taking a break now. Not really having fun at the moment ...

Am Mittwoch, den 30.09.2020, 10:45 -0700 schrieb Craig Leres:
> On 2020-09-30 01:42, Chris van der Meijden wrote:
> > Oh boy ...
> > 
> > Found this one:
> > 
> > http://lists.openvehicles.com/pipermail/ovmsdev/2020-February/00664
> > 0.html
> > 
> > You indeed have to pull the fuse for a minute and not only for two 
> > seconds ...
> > 
> > Very strange, but hey it works now :-)
> > 
> > Network Registration: RegisteredHome Provider: o2 - de+ Signal: -97
> > dBm 
> > State: NetStart
> I have not seen this issue since Mark made the change in April
> described 
> in the attached; he added a uart_flush() call to
> simcom::PowerCycle():
> https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/comm
> it/9de2ecd94da64da6496a57acd0286e48f93dd250
> 		Craig
> -------- Forwarded Message --------
> Subject: 	[Ovmsdev] Modem unable to power cycle successfully
> Date: 	Thu, 16 Apr 2020 10:40:20 +0800
> From: 	Mark Webb-Johnson <mark at webb-johnson.net>
> Reply-To: 	OVMS Developers <ovmsdev at lists.openvehicles.com>
> To: 	OVMS Developers <ovmsdev at lists.openvehicles.com>
> I’ve seen cases where the modem will not come up correctly, even 
> following a power cycle. But, a reset of the OVMS module (ESP32)
> solves 
> the problem. This really makes no sense, unless something is getting 
> corrupted inside the UART / EGPIO driver itself. The modem module
> status 
> is not changed during an ESP32 reset - only the software side of it 
> running in the ESP32.
> Thomas Heder has reported some success with using uart_flush to
> flush 
> the UART ring buffer when power cycling the modem. Flushing the
> buffer 
> would not seem to affect this, as we use ‘AT’ to look for an OK
> response 
> during power up check anyway; but perhaps something is corrupt in
> the 
> ring buffer itself, so using uart_flush clears that problem.
> Note that uart_flush is an alias for uart_flush_input, and the
> source 
> code does seem to show a complete reset of the ring buffer pointers
> with 
> interrupts disabled (not just a simple emptying).
> Anyway, the approach does not seem to do any harm, so I have added it
> to 
> the latest code and let’s see if it improves the situation.
> https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issu
> es/354
> Regards, Mark.
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