PIC16F193X Datasheet, PDF (250/418 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

PIC16F193X/LF193X
21.2 LCD Clock Source Selection
The LCD module has 3 possible clock sources:
• FOSC/256
• T1OSC
• LFINTOSC
The first clock source is the system clock divided by
256 (FOSC/256). This divider ratio is chosen to provide
about 1 kHz output when the system clock is 8 MHz.
The divider is not programmable. Instead, the LCD
prescaler bits LP<3:0> of the LCDPS register are used
to set the LCD frame clock rate.
The second clock source is the T1OSC. This also gives
about 1 kHz when a 32.768 kHz crystal is used with the
Timer1 oscillator. To use the Timer1 oscillator as a
clock source, the T1OSCEN bit of the T1CON register
should be set.
The third clock source is the 31 kHz LFINTOSC, which
provides approximately 1 kHz output.
The second and third clock sources may be used to
continue running the LCD while the processor is in
Sleep.
FIGURE 21-2:
LCD CLOCK GENERATION
Using bits CS<1:0> of the LCDCON register can select
any of these clock sources.
21.2.1 LCD PRESCALER
A 4-bit counter is available as a prescaler for the LCD
clock. The prescaler is not directly readable or writable;
its value is set by the LP<3:0> bits of the LCDPS register,
which determine the prescaler assignment and prescale
ratio.
The prescale values are selectable from 1:1 through
1:16.
FOSC _÷256
To Reference
Ladder Control
T1OSC 32 kHz
÷4 ^Static
5
Crystal Osc.
÷2
1/2
4-bit Prog
÷32
Prescaler
÷1, 2, 3, 4
Ring Counter
1/3,
LFINTOSC
1/4
Nominal = 31 kHz
CS<1:0>
LP<3:0>
(LCDPS<3:0>)
LMUX<1:0>
LMUX<1:0>
(LCDCON<1:0>)
(LCDCON<3:2>) (LCDCON<1:0>)
DS41364A-page 248
Preliminary
© 2008 Microchip Technology Inc.