# About PSM wakeup source

**URL:** <https://mangoh.discourse.group/t/about-psm-wakeup-source/9653>\
**Category:** Uncategorized\
**Created:** [September 11, 2021, 6:45am UTC](https://mangoh.discourse.group/t/about-psm-wakeup-source/9653 "2021-09-11T06:45:11Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![jyijyi](https://sea2.discourse-cdn.com/flex016/user_avatar/mangoh.discourse.group/jyijyi/32/997_2.png) [@jyijyi](https://mangoh.discourse.group/u/jyijyi)\
**Post date:** [September 12, 2021, 11:41am UTC](https://mangoh.discourse.group/t/about-psm-wakeup-source/9653/3 "2021-09-12T11:41:04Z")

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BTW, I also suggest you to try ULPM mode first:

> [@MangOH Yellow power optimization](https://mangoh.discourse.group/t/mangoh-yellow-power-optimization/4216/2):
>
> Hi Paul, One big way to reduce power is to put the HSIC interface into suspend mode. This can drop power by 60 ma. –\> echo 0 \> /sys/bus/usb/devices/usb1/authorized Also make sure wakelock is set in case USB cable is removed: –\> echo NO\_SLEEP \> /sys/power/wake\_lock Also, if you are ready to take a soldering iron, you can get some more improvements: a. Add R306 (0R), and check that EXT\_GPS\_LNA\_EN signal is set 0. Should be 4ma saving b. Savings over LEDs: –\> echo ‘AT!LEDTEST=0,1;!LEDTEST=…

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