PIC16C926 Microchip Technology Inc., PIC16C926 Datasheet - Page 91

• Manufacturer Part Number: PIC16C926
• Description: 64/68-pin Cmos Microcontrollers With Lcd Driver
• Manufacturer: Microchip Technology Inc.

11.1
The LCD module has 3 possible clock source inputs
and supports static, 1/2, 1/3, and 1/4 multiplexing.
11.1.1
The clock sources for the LCD timing generation are:
• Internal RC oscillator
• Timer1 oscillator
• System clock divided by 256
The first timing source is an internal RC oscillator which
runs at a nominal frequency of 14 kHz. This oscillator
provides a lower speed clock which may be used to
continue running the LCD while the processor is in
SLEEP. The RC oscillator will power-down when it is
not selected or when the LCD module is disabled.
FIGURE 11-6:
2001 Microchip Technology Inc.
Crystal Oscillator
F
Nominal F
Internal RC Oscillator
TMR1 32 kHz
OSC
LCD Timing
TIMING CLOCK SOURCE
SELECTION
RC
256
= 14 kHz
LCD CLOCK GENERATION
CS1:CS0
2
4
Preliminary
LMUX1:LMUX0
Static
1/2
1/3
1/4
The second source is the Timer1 external oscillator.
This oscillator provides a lower speed clock which may
be used to continue running the LCD while the proces-
sor is in SLEEP. It is assumed that the frequency pro-
vided on this oscillator will be 32 kHz. To use the
Timer1 oscillator as a LCD module clock source, it is
only necessary to set the T1OSCEN (T1CON<3>) bit.
The third source is the system clock divided by 256.
This divider ratio is chosen to provide about 32 kHz
output when the external oscillator is 8 MHz. The
divider is not programmable. Instead the LCDPS regis-
ter is used to set the LCD frame clock rate.
All of the clock sources are selected with bits CS1:CS0
(LCDCON<3:2>). Refer to Register 11-1 for details of
the register programming.
4-bit Programmable
CPCLK
LCDPS<3:0>
Prescaler
Data Bus
internal
PIC16C925/926
32
LMUX1:LMUX0
Ring Counter
DS39544A-page 89
1,2,3,4