377中CPU内部温度可以通过AD读取，如何转换为实际温度呢？
8.3.4 Internal Temperature Sensor
The internal temperature sensor measures the junction temperature of the device. The output of the
sensor can be sampled with the ADC through an internal connection. This can be enabled on channel
ADCIN13 on ADCA by setting the ENABLE bit in the TSNSCTL register. When sampling the temperature
sensor, the external signal on the ADCINA13 pin has no effect on the conversion result.
