PIC16F819 Microchip Technology Inc., PIC16F819 Datasheet - Page 38

• Manufacturer Part Number: PIC16F819
• Description: 18/20-pin Enhanced Flash Microcontrollers With Nanowatt Technology
• Manufacturer: Microchip Technology Inc.

PIC16F818/819
4.5.2
The internal oscillator’s output has been calibrated at the
factory but can be adjusted in the application. This is
done by writing to the OSCTUNE register (Register 4-1).
The tuning sensitivity is constant throughout the tuning
range. The OSCTUNE register has a tuning range of
±12.5%.
REGISTER 4-1:
DS39598E-page 36
bit 7-6
bit 5-0
OSCTUNE REGISTER
OSCTUNE: OSCILLATOR TUNING REGISTER (ADDRESS 90h)
Unimplemented: Read as ‘0’
TUN<5:0>: Frequency Tuning bits
011111 = Maximum frequency
011110 =
•
•
•
000001 =
000000 = Center frequency. Oscillator module is running at the calibrated frequency.
111111 =
•
•
•
100000 = Minimum frequency
bit 7
Legend:
R = Readable bit
-n = Value at POR
U-0
—
U-0
—
R/W-0
TUN5
W = Writable bit
‘1’ = Bit is set
R/W-0
TUN4
When the OSCTUNE register is modified, the INTOSC
and INTRC frequencies will begin shifting to the new fre-
quency. The INTRC clock will reach the new frequency
within 8 clock cycles (approximately 8 * 32 s = 256 s);
the INTOSC clock will stabilize within 1 ms. Code execu-
tion continues during this shift. There is no indication that
the shift has occurred. Operation of features that depend
on the 31.25 kHz INTRC clock source frequency, such
as the WDT, Fail-Safe Clock Monitor and peripherals,
will also be affected by the change in frequency.
R/W-0
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
TUN3
R/W-0
TUN2
 2004 Microchip Technology Inc.
x = Bit is unknown
R/W-0
TUN1
R/W-0
TUN0
bit 0