PIC18F87K90 Datasheet, PDF (297/566 Pages) Microchip Technology – 64/80-Pin, High-Performance Microcontrollers with LCD Driver and nanoWatt XLP Technology

PIC18F87K90 FAMILY
20.10 Operation During Sleep
The LCD module can operate during Sleep. Setting the
SLPEN bit (LCDCON<6>) allows the LCD module to go
to Sleep. Clearing this bit allows the module to continue
operating during Sleep.
If a SLEEP instruction is executed and SLPEN = 1, the
LCD module will cease all functions and go into a very
low-current consumption mode. The module will stop
operation immediately and drive the minimum LCD volt-
age on both segment and common lines. Figure 20-19
shows this operation.
The LCD module current consumption will not
decrease in this mode, but the overall consumption of
the device will be lower due to shut down of the core
and other peripheral functions.
To ensure that no DC component is introduced on the
panel, the SLEEP instruction should be executed
immediately after an LCD frame boundary. The LCD
interrupt can be used to determine the frame boundary.
For the formulas to calculate the delay, see
Section 20.9 “LCD Interrupts”.
If a SLEEP instruction is executed and SLPEN = 0, the
module will continue to display the current contents of
the LCDDATA registers. The LCD data cannot be
changed.
To allow the module to continue operation while in
Sleep, the clock source must be either the internal RC
oscillator or Timer1 external oscillator.
If the system clock is selected and the module is
programmed to not Sleep, the module will ignore the
SLPEN bit and stop operation immediately. The
minimum LCD voltage then will be driven onto the
segments and commons.
Note:
The internal RC oscillator or external
SOSC oscillator must be used to operate
the LCD module during Sleep.
FIGURE 20-19: SLEEP ENTRY/EXIT WHEN SLPEN = 1 OR CS<1:0> = 00
V₃
V₂
V₁
COM0
V₀
V₃
V₂
V₁
COM1
V₀
V₃
V₂
V₁
COM2
V₀
V₃
V₂
V₁
SEG0
V₀
2 Frames
SLEEP Instruction Execution
Wake-up
 2010 Microchip Technology Inc.
Preliminary
DS39957B-page 297