This changes the CC26xx simple demo so that a devices running this firmware will achieve the lowest possible energy consumption without requiring any changes to the example
* Only enable TX by default.
* Add some magic for RX handling. When an input handler is registered:
* Automatically enable RX-related and interrupts
* Automatically lock the SERIAL PD on under all power modes
* Automatically enable the UART clock under sleep and deep sleep
* Automatically undo all of the above when the input handler becomes NULL
* As a result, modules / examples that need UART RX no longer need to clock the UART and manipulate the SERIAL PD. They simply have to specify an input handler
* Don't automatically power on the UART whenever the CM3 is active
* Before accessing the UART, make sure it is powered and clocked
* Avoid falling edge glitches
* Fix garbage characters / Explicitly wait for UART TX to complete
* Implement new style of PD locks
* Use our own shutdown sequence rather than the one provided by cc26xxware
* Shutdown from within the interrupt that requested it. This allows shutdown to take place even if the code is stuck in a loop somewhere else
* Improve DCDC/GLDO/uLDO switching logic
* Explicitly handle oscillators and retentions
* Keep MPU_PWR low when the sensor is not in use
* Deselect the sensor when not in use, in order to restore the I2C ping state
* Explicitly control the MPU_INT pin
* Don't shutdown the sensor when it's shut down
* Remove explicit shutdown-related API extension. It is no longer required
Instead of using a separate data structure to request that a PD remain powered during deep sleep,
we do the same within the main LPM data structure through an additional field.
This allows us to maintain only one linked list of LPM modules and overall improves code clarity
We only power, clock and enable the peripepheral when / if we need it
* We no longer automatically turn on the SERIAL PD when the CM3 is running
* Make sure the I2C peripheral is accessible (powered and clocked) before any operation
* If the peripheral is not accessible, automatically power it up and run the clock
* Put SDA, SCL, SDA HP and SCL HP in a low-leakage state when shutting down
* Don't automatically fire up the I2C controller when we wake up
* Explicitly put in deep sleep on device startup
* Verify that the flash has actually dropped to deep sleep
* Update CLK pin to match the one used on the v1.2 sensortag
Obsoletes and Closes#988
* Query the sensor about its state, rather than using variables in the driver
* Correctly put the sensor to deep sleep
* Fix doxygen comments
* Don't turn off the sensor in examples since it is no longer needed
