The DCO frequency can be calibrated and set to a specific
frequency with compensation for changes in voltage, temperature,
and differences between parts. Generally a low speed crystal or
external signal is used for this purpose by comparing the number
of high speed DCO clock cycles that occur during one cycle of the
low speed reference frequency. Using software, Basic Clock control
registers are adjusted to set the DCO to the desired frequency
multiple of the slower crystal or signal. The device datasheet
details the operating range of the DCO. The MSP430x1xx User`s Guide
provides details of the Basic Clock.
Example code and application reports that demonstrates the setting
of the DCO are available from the MSP430 website.