sleep command doesn't work.

[SaitoYutaka]

$ qemu-system-arm -M microbit -device loader,file=nuttx -serial stdio

NuttShell (NSH)
nsh> ls
/:
 dev/
nsh> help
help usage:  help [-v] [<cmd>]

  [         cd        echo      hexdump   mkfatfs   mw        sh        uname     
  ?         cp        exec      kill      mkrd      pwd       sleep     umount    
  basename  cmp       exit      ls        mh        rm        test      unset     
  break     dirname   false     mb        mount     rmdir     time      usleep    
  cat       dd        help      mkdir     mv        set       true      xd        

Builtin Apps:
  hello  nsh    
nsh> sleep 1
# no action

[SaitoYutaka]

It seems to be BOARD_SYSTICK_CLOCK 's value is wrong.

https://github.com/SaitoYutaka/incubator-nuttx/blob/nuttx-microbit/arch/arm/src/nrf51/nrf51_timerisr.c#L80

https://github.com/SaitoYutaka/incubator-nuttx/blob/nuttx-microbit/boards/arm/nrf51/microbit/include/board.h#L56

[SaitoYutaka]

See
https://devzone.nordicsemi.com/f/nordic-q-a/16/does-the-nrf51822-have-a-systick-timer

[SaitoYutaka]

Use RTC1.

c1d7b9c