PIC16F946 Datasheet, PDF (80/274 Pages) Microchip Technology – 64-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

PIC16F946
4.4.2.1 OSCTUNE Register
The HFINTOSC is factory calibrated but can be
adjusted in software by writing to the OSCTUNE
register (Register 4-2).
The OSCTUNE register has a tuning range of ±12%.
The default value of the OSCTUNE register is ‘0’. The
value is a 5-bit two’s complement number. Due to
process variation, the monotonicity and frequency step
cannot be specified.
When the OSCTUNE register is modified, the HFINTOSC
frequency will begin shifting to the new frequency. The
HFINTOSC clock will stabilize within 1 ms. Code
execution continues during this shift. There is no
indication that the shift has occurred.
OSCTUNE does not affect the LFINTOSC frequency.
Operation of features that depend on the LFINTOSC
clock source frequency, such as the Power-up Timer
(PWRT), Watchdog Timer (WDT), Fail-Safe Clock
Monitor (FSCM) and peripherals, are not affected by the
change in frequency.
REGISTER 4-2:
OSCTUNE – OSCILLATOR TUNING RESISTOR (ADDRESS: 90h)
U-0
U-0
U-0
R/W-0 R/W-0 R/W-0 R/W-0
—
—
—
TUN4
TUN3
TUN2
TUN1
bit 7
R/W-0
TUN0
bit 0
bit 7-5
bit 4-0
Unimplemented: Read as ‘0’
TUN<4:0>: Frequency Tuning bits
01111 = Maximum frequency
01110 =
•
•
•
00001 =
00000 = Center frequency. Oscillator module is running at the calibrated frequency.
11111 =
•
•
•
10000 = Minimum frequency
Legend:
R = Readable bit
- n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
DS41265A-page 78
Preliminary
© 2005 Microchip Technology Inc.