The maximum clock frequency for the MSP430F2001IN is 16 MHz, but it can be operated at frequencies up to 20 MHz with reduced voltage and temperature ranges.
To use an external clock source, connect the clock signal to the XIN pin and set the UCSSELx bits in the UCSCTL6 register to select the external clock source. Also, make sure to configure the XT2 oscillator by setting the XT2OFF bit in the UCSCTL6 register to 0.
The minimum voltage required for the MSP430F2001IN to operate is 1.8V, but it is recommended to operate at a minimum of 2.2V for reliable operation.
To use the built-in UART module, configure the UART pins as outputs by setting the PxDIR register, then configure the UART mode by setting the UCMODEx register, and finally set the baud rate by writing to the UCBRx register.
Yes, the MSP430F2001IN can be used with a 3.3V power supply, but it is recommended to use a voltage regulator to ensure a stable voltage supply to the device.