Texas Instruments MSP430x1xx - Manual (Page 102)

7-2
7.1 Basic Clock Module
The Basic Clock Module (shown in Figure 7–1) follows the major targets of low
system cost and low power consumption. Using three internal clock signals,
the design engineer can select the best balance of performance and low power
consumption. The Basic Clock Module can be configured to operate without
any external components, with one external resistor, with one or two external
crystals, with resonators, or with clock sources using any combination of the
above. The Basic Clock Module is accessible to the CPU as a byte-wide
peripheral module.
Figure 7–1. Basic Clock Schematic
DIVA
XT2Off
XIN
LFXT1 Oscillator
ACLK
OSCOff XTS
/1, /2, /4, /8
2
DIVM
/1, /2, /4, /8, Off
2 2
SELM CPUOff
Auxiliary Clock
MCLK
Main System Clock
DIVS
/1, /2, /4, /8, Off
2
SELS SCG1
SMCLK
Sub-System Clock
XOUT
XT2IN
XT2OUT
SMCLKGEN
LFXT1CLK
XT2CLK
MCLKGEN
ACLKGEN
DCOMOD
XT2
Oscillator
Digital Controlled Oscillator DCO
+
Modulator MOD
DC
Generator
5 3
DCO MOD Rsel SCG0
DCOR
If the external resistor function is shared on a digital terminal, the DCOR control
bit defines if the digital port of the DCO generator is connected to that terminal.
Pn.x
VCC VCC
0
1
Note: The XT2 oscillator is implemented in MSP430F13x and MSP430F14x devices. The LFXT1 signal is used instead of XT2CLK signal in
MSP430x11x and MSP430x11x1 devices without XT2 oscillator.
3
0,1
2
0
1
DCOCLK