20180725 First release, uart demo application.
20180730 Add i2c (master & slave) demo application.
20180829 use updated lib v4.0.0, add api and update demo code.
20181226 use updated lib v4.0.2, add api, add PWM and LowPower reference code.
20190307 use updated lib v4.1.3, update i2c demo reference code.