The sample in PAL_AMB is slightly modified so that the waiting time (approx. 50 ms) during sensor data acquisition is replaced by a sleep wait.
Please see the explanation of the ACT in PAL_AMB before the explanation of this ACT.
The begin() function exits the setup() function (after which TWENET is initialized) and is called just before the first loop().
The first sleep is performed after setup() ends. Although sensor data acquisition is started during setup(), this result is not evaluated and is not necessarily necessary, since it means that the sensor is run once in advance.
Procedures after waking up. The following process is performed.
If the sensor data acquisition start has not yet been performed, the sensor data acquisition is performed and a short sleep is entered.
Since the start of sensor data acquisition was performed immediately before, the data is checked and sent wirelessly.
The above branch is controlled by the global variable b_sensor_started. If !b_sensor_started, it starts acquiring a sensor (startSensorCapture()) and goes into a short sleep by napNow(). The time is 100ms.
After returning from sleep by napNow(), the clause b_sensor_started==true is executed. Here, the E_EVENT_START_UP event is notified to the two sensors. This event means that enough time has passed for the sensors to finish acquiring. Based on this notification, sns_LTR308ALS and sns_SHTC3 are made available. After this, it will go to loop() and wireless packets will be sent.
The event that notifies the sensor is used to determine if the required time wait is over. Whether or not the actual time has elapsed depends on whether or not the correct time was set with napNow(). If the wake-up time is short, it is expected that the time elapsed is not enough to meet the required time elapsed and that subsequent processing will result in errors such as sensor data not being available.
Perform a very short sleep.
If the second parameter of sleep is set to true, the next wake-up time is adjusted based on the previous sleep wake-up time. This is useful if you always want to wake up every 5 seconds.
If the third parameter is set to true, the sleep mode is set without memory retention. After waking up, wakup() will not be called and the process will be the same as power-on.
The fourth specifies the use of the second wake-up timer. Here, the first is used for normal sleep and the second is used for short sleep. There is no strong reason to use the second timer in this ACT, but if, for example, the user wants to wake up every 5 seconds as described above, using the first timer for a short sleep would reset the counter value, which would complicate the elapsed time correction calculation, so the second timer is used.
Setting too short a sleep time does not balance the energy cost of reinitializing the system after returning from sleep. As a rule of thumb, the minimum time should be 30-50 ms.