Linux是有低功耗模式的（Low Power Mode）,emcraft的STM32F7也实现了这个功能，它支持suspend to RAM模式。也就是电脑上常说的挂起到内存。
在STM32F750开发板上可以通过命令行使系统挂起，使用SW3 button唤醒系统（wake up）。
! l+ u, M# m, e/ |8 j, D0 ~8 A1. 系统正常启动，测量5V输入端电流，大约210mA

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3 S* [0 V: _6 N" b" a; D# G. n( r) i2. 在控制台输入系统挂起命令

9 Z! w" e$ h, Q( L( {# U- v; j/ # echo mem > /sys/power/state
PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.007 seconds) done.
" y  t9 J, l; pFreezing remaining freezable tasks ... (elapsed 0.014 seconds) done.
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这时测得的系统电流消耗大约10mA（由于所用万用表只有10A档适合测量这个板子的电流，如果有合适的mA档其实应该更精确一些的）



2 p$ E0 Q' e% j. X% n0 E3. 按下SW3 button系统恢复运行

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dwc2 50000000.usb: suspending usb gadget g_serial
dwc2 50000000.usb: s3c_hsotg_ep_disable: called for ep0
9 M% y: v  e! Odwc2 50000000.usb: s3c_hsotg_ep_disable: called for ep0
PM: suspend of devices complete after 5.553 msecs
8 h- w, ]7 N7 c/ aPM: late suspend of devices complete after 4.632 msecs
PM: noirq suspend of devices complete after 2.482 msecs
/ _3 M7 Y5 J& t, r! n; ^2 aPM: noirq resume of devices complete after 1.748 msecs
0 p, X- |- R5 j" N9 n5 uPM: early resume of devices complete after 2.316 msecs
: v2 a. m' ~6 x" tdwc2 50000000.usb: resuming usb gadget g_serial
% g9 }+ W- _8 T3 `7 PPM: resume of devices complete after 111.242 msecs
9 i0 X; R) t4 G. c, sRestarting tasks ... done.
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此时系统电流重新回到210mA左右。
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