[Ovmsdev] Cannot reset simcom stuck in PoweringOn state without removing module power

[Mark Webb-Johnson]

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.

> On 17 Nov 2019, at 8:11 PM, Michael Balzer <dexter at expeedo.de> 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:
>> 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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> 
> -- 
> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
> 
> 
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