Sleep Management

The sensor host follows a periodic sleep routine as described below.

../../_images/sh_sleep_timeline.png

The following actions are described below:

  1. Start: At the start of this periodic routine, the sensor host must determine how long it needs to sleep for, this period denoted Processing is reserved for this calculation. The routine responsible for this calculation is calc_time_sleep, returning the value \(T_{AVR,sleep}\)
  2. Periodic Sleep: The device then sleeps for the prescribed time.
  3. Timer Wake: An interrupt generated by Timer2 wakes the device. As this wake state requires a period of time to re-initialise the system, the time returned from calc_time_sleep is reduced by an overhead time
  4. Pre-Sample Wait: With the device ready to sample, the device makes a final calculation to ensure the sample is received at the correct time