   Tone::begin();
   RTC::begin();
   uart.begin(9600);
+  yield = iowait;
 }
 
 void loop()
 {
   shell.run(ios);
-  iowait();
+  yield();
 }
 

#include "Commands.h"
#include "Cosa/RTC.hh"
#include "Cosa/Tone.hh"
#include "Cosa/Watchdog.hh"
#include "Cosa/IOStream/Driver/UART.hh"


void iowait()
{
  uint32_t start = RTC::micros();
  Power::sleep(); 
  uint32_t stop = RTC::micros();
  idle = idle + (stop - start);
}

void setup()
