Interface Powerdown

This note discusses an experimental (== unsupported) mbed interface firmware version which allows you to instruct it to power down. This has the effect of disconnecting the interface as a debugger and disabling the USB interface.

The semantics are:

  • The target can make a semihosting call to the interface to request it to power down
  • If USB is not connected, the interface will detach its debug connection to the target, then power down
  • If USB is connected, it will be ignored and the mbed will function as normal
  • The interface will be restored again after a power cycle

The experimental firmware is at:

To load it, drag it on to your mbed and power-cycle. If you want to revert to the standard firmware at any time, go to /handbook/Firmware.

To request a powerdown, take a look at the example program:

Note, as the call is ignored when USB is connected, you can always plug in your mbed and reprogram it as normal.


19 Dec 2010 . Edited: 19 Dec 2010

Dose the new boot loader put IC1 it into

  • Sleep
  • Deep Sleep
  • Power Down
  • Deep Power Down

when  "__semihost( USR_POWERDOWN, &arg );" is called?

I also note that " #pragma NOINIT" & " #pragma INIT" don't work with the compiler. When trying to store vars for watchdog trace back.

#define WDG_LINE() (wdg_line = __LINE__)

#pragma NOINIT
uint16_t wdg_cnt;
int      wdg_line;
#pragma INIT

22 Jul 2011 . Edited: 22 Jul 2011

Did this ever get added to the main libs, if not how can I make a lib out of the expermental lib

23 Jul 2011 . Edited: 23 Jul 2011

I see __IO uint32_t PowerDown;  and that's it... what am I supposed to be looking for...........

28 Jul 2011 . Edited: 29 Jul 2011
Can no anyone can wake up from DeepSleep by any InterruptIn? While, sleep works right and, wakes up by an interrupt.
07 Oct 2011 . Edited: 07 Oct 2011

I seem to be able to reset from DeepSleep using the watchdog timer - see

14 Feb 2013
Does anybody know if the features of this experimental firmware were integrated in one of the latest firmaware release? (e.g. rev 16457)

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