PIC16F913/914/916/917/946
10.11 Configuring the LCD Module
10.13 LCD Current Consumption
The following is the sequence of steps to configure the
LCD module.
When using the LCD module the current consumption
consists of the following three factors:
1. Select the frame clock prescale using bits
LP<3:0> of the LCDPS register.
1. The oscillator selected
2. The LCD bias source
2. Configure the appropriate pins to function as
segment drivers using the LCDSEn registers.
3. The current required to charge the LCD
segments
3. Configure the LCD module for the following
using the LCDCON register:
The current consumption of just the LCD module can
be considered negligible compared to these other
factors.
- Multiplex and Bias mode, bits LMUX<1:0>
- Timing source, bits CS<1:0>
- Sleep mode, bit SLPEN
The oscillator selected:
For LCD operation during Sleep either the T1oc or the
LFINTOSC sources need to be used as the main
system oscillator may be disabled during Sleep. During
Sleep the LFINTOSC current consumption is given by
electrical parameter D021, where the LFINTOSC use
the same internal oscillator circuitry as the Watchdog
Timer.
4. Write initial values to pixel data registers,
LCDDATA0 through LCDDATA11 (LCDDATA23
on PIC16F946).
5. Clear LCD Interrupt Flag, LCDIF bit of the PIR2
register and if desired, enable the interrupt by
setting bit LCDIE of the PIE2 register.
6. Enable bias voltage pins (VLCD<3:1>) by
setting bit VLCDEN of the LCDCON register.
The LCD bias source:
The LCD bias source, typically an external resistor
ladder which will have its own current draw.
7. Enable the LCD module by setting bit LCDEN of
the LCDCON register.
The current required to charge the LCD segments:
10.12 Disabling the LCD Module
The LCD segments which can be modeled as capaci-
tors which must be both charged and discharged every
frame. The size of the LCD segment and its technology
determines the segment’s capacitance.
To disable the LCD module, write all ‘0’s to the
LCDCON register.
© 2007 Microchip Technology Inc.
DS41250F-page 167
MICROCHIP [ MICROCHIP ]
