no current/amp reduction with Power save mode for NB-IOT sim7020G in M5 COM.NB-IoT module ?

tsil

Hi

I connect an amp meter between the 5V pin in the M5 module and the 5V supply.
I run the AT command AT+CPSMS=1,,,"01000101","00100010"
I get the message after one minute that power save mode is turned on.
but the current stays on 10mA, no reduction.

Anyone see what I am doing wrong ?

BR
/T

felmue

Hello @tsil

on the green board there is an additional DC-DC converter which most likely takes about the same amount of current whether the SIM7020G module is in power save mode or not.

I guess you'd need to cut the power trace, on the green board, that comes from that DC-DC converter and goes into the SIM7020G module and measure the current there.

Thanks
Felix

tsil

@felmue

Ok, so there is no power saving when I use the 5 V pin, can I use some other pin on the M5 COM.NB-IoT module to be able to achieve power savings when using PSM or eDRX ?

BR
/T

felmue

Hello @tsil

can I use some other pin on the M5 COM.NB-IoT module ...

not that I know of.

Note: most M5Stack devices, modules, units, etc. hardware designs are quite bad when it comes to power saving. Mostly the culprit is the power regulator which by itself uses quite some energy even when the load is very low.

Note: there are some M5Stack devices (e.g. M5Paper) which allow the system to fully shutdown and only keep the RTC running. These systems can achieve some level of power saving.

Thanks
Felix

tsil

Thanks you for your quick reply and good info !
BR
/T