PIC18LF24K Datasheet, PDF (398/594 Pages) –

PIC18(L)F26/45/46K40
27.3 Clock Accuracy with
Asynchronous Operation
The factory calibrates the internal oscillator block
output (INTOSC). However, the INTOSC frequency
may drift as VDD or temperature changes, and this
directly affects the asynchronous baud rate. Two
methods may be used to adjust the baud rate clock, but
both require a reference clock source of some kind.
The first (preferred) method uses the OSCTUNE
register to adjust the INTOSC output. Adjusting the
value in the OSCTUNE register allows for fine resolution
changes to the system clock source. See Section
4.3.2.3 “Internal Oscillator Frequency Adjustment”
for more information.
The other method adjusts the value in the Baud Rate
Generator. This can be done automatically with the
Auto-Baud Detect feature (see Section
27.4.1 “Auto-Baud Detect”). There may not be fine
enough resolution when adjusting the Baud Rate
Generator to compensate for a gradual change in the
peripheral clock frequency.
 2016 Microchip Technology Inc.
Preliminary
DS40001816C-page 398