DCORSEL的设置好像很宽泛，比如下面的代码
查datasheet发现在DCOx和MODx的设置为0000时，DCO的范围并不能到4.9Mhz
__bis_SR_register(SCG0); // Disable the FLL control loop
UCSCTL0 = 0x0000; // Set lowest possible DCOx, MODx
UCSCTL1 = DCORSEL_3; // Set RSELx for DCO = 4.9 MHz
UCSCTL2 = FLLD_1 + 74; // Set DCO Multiplier for 2.45MHz

datasheet：
fDCO(3,0) DCO frequency (3, 0) DCORSELx = 3, DCOx = 0, MODx = 0 0.64 1.51 MHz
fDCO(3,31) DCO frequency (3, 31) DCORSELx = 3, DCOx = 31, MODx = 0 6.07 14.0 MHz 此帖出自小平头技术问答