# MangOH Yellow power optimization

**URL:** <https://mangoh.discourse.group/t/mangoh-yellow-power-optimization/4216>\
**Category:** mangOH Yellow\
**Created:** [April 6, 2020, 7:39am UTC](https://mangoh.discourse.group/t/mangoh-yellow-power-optimization/4216 "2020-04-06T07:39:38Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![asyal](https://sea2.discourse-cdn.com/flex016/user_avatar/mangoh.discourse.group/asyal/32/78_2.png) [@asyal](https://mangoh.discourse.group/u/asyal)\
**Post date:** [April 8, 2020, 5:43am UTC](https://mangoh.discourse.group/t/mangoh-yellow-power-optimization/4216/2 "2020-04-08T05:43:12Z")

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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=0,0’ \> /dev/ttyAT (Red LED off, 1.5ma)  
–\> Remove R428, save couple of ma  
c. Remove USB cable (have a wakelock running though): 12-15ma  
d. If you want to, you can force the DC/DC buck converter into automatic PFM/PWM mode . Save around 10 ma. Remove R901,remove c901. Add 10K between r901.pin\_mode to c901.gnd. ![image](https://us1.discourse-cdn.com/flex016/uploads/mangoh/original/2X/7/7400720cf0953abcc558cbedcd982768d259112c.png)  
e. Run CPU in interactive mode:  
—\> echo interactive \> /sys/bus/cpu/devices/cpu0/cpufreq/scaling\_governor

If you want to know how low the board can go, you can remove R908 and add R909.  
Then pull-up pin 3 of SW401. This will allow you to power off everything on the board except the module and the ULPM circuitry. If you bring down pin 3 of SW401, you will get all circuitry powered back up. We see module consuming 1.0ma and sensor circuitry at 1.3ma.

Further, you can put the board in ULPM mode:  
AT!POWERWAKE=CLEAR

AT!POWERWAKE=1,60

AT!POWERMODE=1 (VGPIO gets low)

I will publish this on the mangoh website over the next few days . Let me know what numbers you hit.  
Would be great if you can post your numbers here.

regards,  
Ashish

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