Texas Instruments MSP430x1xx - Manual (Page 111)

Digitally-Controlled Oscillator (DCO)
7-11
Basic Clock Module
Figure 7–11. Principle Period Steps of the DCO
f
DCOCLK
Nominal
0 1 2 3 4 5 6 7 DCO
Five bits (SCG0, CPUOff, SELM.1, SCG1, and SELS) control the operation of
the DCO.
Figure 7–12. On/Off Control of DCO
Q D
Q D
CL
CPUOff
XSELM.1
SCG1
SELS
SCG0
SMCLK
POR
DCOCLK
DCOCLK_on
1: on
0: off
DCO_Gen_on
1: on
0: off
SCG0
x
x
0
0
0
0
1
CPUOff
0
x
0
1
SELM.1
0
x
1
x
SCG1
x
0
0
1
SELS
x
0
1
x
DCOCLK
on
on
off
off
off
off
off
Comment
DCO Clock Needed For MCLK
DCO Clock Needed For SMCLK
DCO Clock is Not Needed
For MCLK (and SMCLK)
DCO Clock is Not Needed
For SMCLK (and MCLK)
DCO Clock is Not Needed:
SCG0 Bit Switches Off DCOGEN
NOTES: A. SMCLK does not need the DCOCLK signal if:
SMCLK is switched off (SCG1 = 1), or DOCCLK is not selected for SMCLK (SELS = 0).
B. MCLK does not need the DCOCLK signal if:
MCLK is switched off (CPUOff = 1), or DOCCLK is not selected for MCLK (SELM.1 = 1).
C. MCLK and SMCLK does not need the DCOCLK signal if:
The control bit SCG0 in the status register can switch off (SCG0 = 1) the DCOGEN.
DCOCLK
on
on
on
on
on
on
off
(see Note A)
(see Note B)
(see Note C)