Management of Power Management ;)

[Ben Wilson]

Svetoslav Trochev wrote:
> Ben Wilson wrote: 
>   
>>>> 5. SHR suspend, GSM on: 0.08A
>>>>     
>>>>         
>>> This one looks strange, guys measured it to be ~45mA with uSD
>>> inserted and
>>> ~25mA without.
>>>   
>>>       
>> I measured ~45 / ~25mA most of the time but on two occasions I did see
>> ~75mA, i couldn't reproduce it though.
>> You do see some weird things current wise when gsm is on during suspend.
>>
>> Psi.
>>     
> I think I need more accurate meter here. My old Fluke 23 is only 3 1/2
> digits and don't have needed resolution. I believe that suspend mode is
> failing to turn off some of the hardware in my case. I have not upgraded
> the firmware on my GSM module. Because the SSH connection between the
> Neo1973 and the host PC is dropped when the Neo is suspend I will need
> to connect the serial console to see the messages. Do I need to do
> something special to enable debug messages on the serial console or just
> connect the debug board?
>
> Thank you Psi,
> SAL-e
>   
ya really need an oscilloscope to measure the current with GSM on, as 
changes too much for a normal DMM to give an accurate reading.
I was using a scope across a resistor when i did my measurements.

Problem I found was the voltage loss in the wires and resistor at peak 
current. The phone kept shutting off due to low voltage.
Ended up making this with some nice and thick wires.
http://psi.abcom.co.nz/fakebat.jpg
The contacts I used are out of an old Nokia phone (phone, not battery).
Even then I sometimes had to short out the shunt resistor until it had 
booted up and suspended.

Psi.