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Craig, Mark,<br>
<br>
I just stumbled upon a misreading from my side:<br>
<br>
I had accidentally taken the v3.0 schematics of the main board for
reference, that only had pull-ups on ports 1 & 2. There was a
change in v3.1 adding pull-up resistors on ports 0 & 3 as well.<br>
<br>
So with a 3.1/3.2 module, there actually is a 10K pullup on both
MDM_EN and MDM_DTR, before the transistor.<br>
<br>
With that 10K, we have this transistor control:<br>
<img src="cid:part1.8D922A6C.F803CC13@expeedo.de" alt=""><br>
<br>
<br>
That should result in ~1.5V at the base on MDM_EN high, enough for
the transistor to switch, so I don't know what's going wrong here.<br>
<br>
You can access both pullups from the side, they are located left of
the S2 switch on the main board. R8 is on MDM_EN, R9 on MDM_DTR. R8
shows that very short rise in voltage on transition to high, while
R9 shows the expected behaviour of a constant +3.3 when the port is
high.<br>
<br>
Regards,<br>
Michael<br>
<br>
<br>
<div class="moz-cite-prefix">Am 18.11.19 um 02:47 schrieb Mark
Webb-Johnson:<br>
</div>
<blockquote type="cite"
cite="mid:96E4F7CB-37A8-423B-9D7D-FCF76C5D34C5@webb-johnson.net">
<pre class="moz-quote-pre" wrap="">
I don’t think that circuit has changed since the very first v1 of OVMS. Maybe we have been lucky in the past with the timing?
I will discuss it with the manufacturer, as that part of the circuit is his design and he should know the thinking behind it the best.
Our intention it have EGPIO #0 able to control the PWRKEY of the modem - so as to be able to power it up/down under program control. We are not really controlling the power to the modem - more telling the modem to control itself.
Regards, Mark.
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">On 17 Nov 2019, at 8:11 PM, Michael Balzer <a class="moz-txt-link-rfc2396E" href="mailto:dexter@expeedo.de"><dexter@expeedo.de></a> wrote:
I also saw this & can also reproduce this on my workbench.
Mark, it seems we've got a hardware flaw here: EGPIO output port 0 (MDM_EN) is connected to transistor Q2 base via R16 without any pull-up. As the EGPIO ports
are open drain, that can only work by chance. Maybe R16 was meant to be the pull-up, i.e. be connected to +3.3V, and MDM_EN should be connected directly to the
transistor base?
I've verified this by checking the voltage level at MDM_EN & PWRKEY. When setting the port to 1, MDM_EN only rises for a very short time (too short for my
multimeter to tell), and PWRKEY only drops very briefly. The modem needs PWRKEY low for at least 180ms to power up and at least 500ms to power down.
Manually pushing S1 reliably switches the modem on/off.
Maybe a fix for existing boards could be adding a pullup resistor at the transistor base?
Regards,
Michael
Am 17.11.19 um 02:39 schrieb Craig Leres:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">Maybe this has been discussed and I missed it but occasionally I'll get a module with the modem/simcom stuck in the PoweringOn state. Rebooting does not fix
this.
I thought I saw that you could reset the simcom with:
power simcom off
[wait a minute]
power simcom on
but that doesn't work. I turned up some logging:
log monitor
log level verbose simcom
and I see this happen about every 30 seconds:
I (2204129) simcom: State timeout, transition to 2
I (2204129) simcom: State: Enter PoweringOn state
I (2204129) simcom: Power Cycle
I thought this level of logging would let me see the results of command like:
simcom muxtx 3 at+csq
(signal quality) but I don't see anything after sending it.
Is there a way to hardware reset the simcom? (Is there any reason this doesn't happen when the ovms module reboots?)
Craig
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</blockquote>
<pre class="moz-quote-pre" wrap="">
--
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
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<pre class="moz-quote-pre" wrap="">
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<br>
<pre class="moz-signature" cols="160">--
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
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