Datasheet

dsPIC30F2010
DS70118J-page 124 © 2011 Microchip Technology Inc.
19.2 Oscillator Configurations
19.2.1 INITIAL CLOCK SOURCE
SELECTION
While coming out of Power-on Reset or Brown-out
Reset, the device selects its clock source based on:
a) FOS<1:0> Configuration bits that select one of
four oscillator groups.
b) AND FPR<3:0> Configuration bits that select one
of 13 oscillator choices within the primary group.
The selection is as shown in Table 19-2.
19.2.2 OSCILLATOR START-UP TIMER
(OST)
In order to ensure that a crystal oscillator (or ceramic
resonator) has started and stabilized, an oscillator
start-up timer is included. It is a simple 10-bit counter
that counts 1024 T
OSC cycles before releasing the
oscillator clock to the rest of the system. The time-out
period is designated as T
OST. The TOST time is involved
every time the oscillator has to restart (i.e., on POR,
BOR and wake-up from Sleep). The oscillator start-up
timer is applied to the LP Oscillator, XT, XTL, and HS
modes (upon wake-up from Sleep, POR, and BOR) for
the primary oscillator.
TABLE 19-2: CONFIGURATION BIT VALUES FOR CLOCK SELECTION
Oscillator Mode
Oscillator
Source
FOS1 FOS0 FPR3 FPR2 FPR1 FPR0 OSC2 Function
EC
ECIO
EC w/ PLL 4x
EC w/ PLL 8x
EC w/ PLL 16x
ERC
ERCIO
XT
XT w/ PLL 4x
XT w/ PLL 8x
XT w/ PLL 16x
XTL
HS
Primary
Primary
Primary
Primary
Primary
Primary
Primary
Primary
Primary
Primary
Primary
Primary
Primary
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
1
1
0
0
1
0
0
1
1
0
0
0
0
1
1
0
1
1
0
1
0
1
1
0
0
1
0
1
x
x
CLKO
I/O
I/O
I/O
I/O
CLKO
I/O
OSC2
OSC2
OSC2
OSC2
OSC2
OSC2
LP Secondary
0 0 ————See Note 1 and 2
FRC Internal FRC 0 1 ————See Note 1 and 2
LPRC Internal LPRC
1 0 ————See Note 1 and 2
Note 1: The OSC2 pin is either usable as a general-purpose I/O pin or is completely unusable, depending on the
Primary Oscillator mode selection (FPR<3:0>).
2: Note that the OSC1 pin cannot be used as an I/O pin, even if the Secondary Oscillator or an internal clock
source is selected at all times.