[Ovmsdev] Modem power consumption

[Michael Balzer]

I've never managed to even power on the simcom from my standard USB 2.0 port, so I've had it on a powered hub all the time.

From the SIM5360 hardware design docs:





> For the VBAT, the ripple due
> to GSM/GPRS emission burst (every 4.615ms)may cause voltage drop, and the current consumption rises
> typically to peak of 2A. So the power supply must be able to provide sufficient current up to more than 2A.

So HSPA data transmission + GPS may add up to 550 - 620 mA, and the supply needs to cope with the bursts.

The modem operates at 3.8 V (?), so the 5 V load will be lower, but the ESP and peripherals add.

USB 2.0 is spec'd at 500 mA, 3.0 at 900 mA.

Can someone measure the actual current consumption? My multimeters are far too slow.

Regards,
Michael


Am 17.12.2017 um 04:26 schrieb Greg D.:
> Random data points...
>
> Powering the module from the high power USB port (the one with the
> lightning bolt next to the USB symbol) is rock solid.  GSM connection is
> 2 "bars", as displayed by Android app.  Doesn't matter if WiFi is on or
> off; nicely stable.  I just have a ham radio HT antenna screwed into the
> GSM port (well, it was handy, and I don't have a real GSM antenna). 
>
> If I power the module from my Raspberry Pi 2 (with USB high power
> enabled), the module overall is stable (doesn't crash), but the modem
> never makes it up - the power on message pair just repeat every few
> seconds.  WiFi works, however.
>
> Greg
>
>
> Mark Webb-Johnson wrote:
>> I too have started to see these under-voltage warnings. I’m wondering if it is something to do with the work we recently did to enable GPS. It doesn’t seem to be a problem with powered HUBs or high power boards, so is most likely an actual low voltage condition.
>>
>> Regards, Mark.
>>
>>> On 16 Dec 2017, at 5:59 PM, Tom Parker <tom at carrott.org> wrote:
>>>
>>>
>>> I've found the SIMCOM modem is very unstable when connected to my laptop via an unpowered USB hub. I see under-voltage warnings so I wonder if there isn't enough power? It seems stable when connected directly to my laptop. When it the modem reboots, the esp32 crashes too. I'm not sure if this is because it also ran out of power or because it is sad the network went away:
>>>
>>>
>>>

-- 
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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