PIC16LF1904 Datasheet, PDF (200/288 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt XLP Technology

PIC16LF1904/6/7
19.5 LCD Multiplex Types
The LCD driver module can be configured into one of
four multiplex types:
• Static (only COM0 is used)
• 1/2 multiplex (COM<1:0> are used)
• 1/3 multiplex (COM<2:0> are used)
• 1/4 multiplex (COM<3:0> are used)
The LMUX<1:0> bit setting of the LCDCON register
decides which of the LCD common pins are used (see
Table 19-4 for details).
If the pin is a digital I/O, the corresponding TRIS bit
controls the data direction. If the pin is a COM drive,
then the TRIS setting of that pin is overridden.
TABLE 19-4: COMMON PIN USAGE
Multiplex
LMUX
<1:0>
Static
00
1/2
01
1/3
10
1/4
11
COM3 COM2 COM1
Unused
Unused
Unused
Active
Unused
Unused
Active
Active
Unused
Active
Active
Active
COM1
Active
Active
Active
Active
19.6 Segment Enables
The LCDSEn registers are used to select the pin
function for each segment pin. The selection allows
each pin to operate as either an LCD segment driver or
as one of the pin’s alternate functions. To configure the
pin as a segment pin, the corresponding bits in the
LCDSEn registers must be set to ‘1’.
If the pin is a digital I/O, the corresponding TRIS bit
controls the data direction. Any bit set in the LCDSEn
registers overrides any bit settings in the corresponding
TRIS register.
Note: On a Power-on Reset, these pins are
configured as normal I/O, not LCD pins.
19.7 Pixel Control
The LCDDATAx registers contain bits which define the
state of each pixel. Each bit defines one unique pixel.
Register 19-6 shows the correlation of each bit in the
LCDDATAx registers to the respective common and
segment signals.
Any LCD pixel location not being used for display can
be used as general purpose RAM.
19.8 LCD Frame Frequency
The rate at which the COM and SEG outputs change is
called the LCD frame frequency.
TABLE 19-5: FRAME FREQUENCY
FORMULAS
Multiplex
Frame Frequency⁽²⁾ =
Static
1/2
1/3
1/4
Clock source⁽¹⁾/(4 x (LCD Prescaler) x 32 x 1))
Clock source⁽¹⁾/(2 x (LCD Prescaler) x 32 x 2))
Clock source⁽¹⁾/(1 x (LCD Prescaler) x 32 x 3))
Clock source⁽¹⁾/(1 x (LCD Prescaler) x 32 x 4))
Note 1: Clock source is FOSC/256, T1OSC or LFIN-
TOSC.
2: See Figure 19-2.
TABLE 19-6:
APPROXIMATE FRAME
FREQUENCY (IN Hz) USING
FOSC @ 8 MHz, TIMER1 @
32.768 kHz OR LFINTOSC
LP<3:0>
Static
1/2
1/3
1/4
2
122
122
162
122
3
81
81
108
81
4
61
61
81
61
5
49
49
65
49
6
41
41
54
41
7
35
35
47
35
DS41569A-page 200
Preliminary
 2011 Microchip Technology Inc.