Background tasks in deepSleep() ?

Yes, it is coming out of sleep a bit early sometimes.

Basically the STM32F1 in the Espruino Original board can only wake up on the nearest second (not any more accurately), so what happens is:

• STM32 is in deep sleep
  
• STM32 wakes up <1 second before it has the task to do
  
• Probably it notices that there's still some time to wait - it schedules a high speed timer to wake itself up at the correct time, and goes into a 'normal' sleep
  
• Wakes up from sleep at the correct time to execute code
  
• goes back to deep sleep
  
  

The extra flashes are probably because of that...