PIC16F946T-I/PT Microchip Technology, PIC16F946T-I/PT Datasheet - Page 110

• Manufacturer Part Number: PIC16F946T-I/PT
• Description: Microcontroller
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F946T-I/PT

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 14KB (8K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 336 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TFQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: MA160011 - DAUGHTER BOARD PICDEM LCD 16F91X
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PIC16F946
9.1
The LCD driver module has 3 possible clock sources:
• F
• T1OSC/32
• LFINTOSC/32
The first clock source is the system clock divided by
8192 (F
provide about 1 kHz output when the system clock is
8 MHz. The divider is not programmable. Instead, the
LCD prescaler bits, LCDPS<3:0>, are used to set the
LCD frame clock rate.
The second clock source is the T1OSC/32. 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 (T1CON<3>) bit
should be set.
The third clock source is the 31 kHz LFINTOSC/32, 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.
Using the bits, CS<1:0> (LCDCON<3:2>), any of these
clock sources can be selected.
FIGURE 9-2:
DS41265A-page 108
Note 1:
V
V
V
OSC
DD
DD
DD
*
*
*
/8192
OSC
*
LCD Clock Source Selection
These values are provided for design guidance only and should be optimized for the application by the
designer.
Internal connection.
/8192). This divider ratio is chosen to
LCD Bias 3
10 k *
10 k *
LCD BIAS RESISTOR LADDER CONNECTION DIAGRAM
LCD Bias 2
10 k *
LCD Bias 1
10 k *
10 k *
Preliminary
V
V
V
V
LCD
LCD
LCD
LCD
3
2
1
0
9.1.1
A 16-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 (LCDPS<3:0>), which
determine the prescaler assignment and prescale ratio.
The prescale values from 1:1 through 1:16.
9.2
The LCD driver module can be configured into three
bias types:
• Static Bias (2 voltage levels: V
• 1/2 Bias (3 voltage levels: V
• 1/3 Bias (4 voltage levels: V
This module uses an external resistor ladder to
generate the LCD bias voltages.
The external resistor ladder should be connected to the
Bias 1 pin, Bias 2 pin, Bias 3 pin and V
pin should also be connected to V
Figure 9-2 shows the proper way to connect the
resistor ladder to the Bias pins.
(1)
and V
Note:
To
LCD
Driver
V
V
SS
SS
Connections for External R-ladder
DD
LCD Bias Types
)
LCD PRESCALER
VLCD pins used to supply LCD bias
voltage are enabled on power-up (POR)
and must be disabled by the user by
clearing LCDCON<4>, the VLCDEN bit,
(see Register 9-1).
V
V
V
V
Static Bias
LCD
LCD
LCD
LCD
1/2 Bias
1/3 Bias
0
1
2
3
Static
Bias
© 2005 Microchip Technology Inc.
V
V
—
—
DD
SS
SS
SS
SS
, 1/2 V
, 1/3 V
1/2 Bias 1/3 Bias
1/2 V
1/2 V
DD
V
V
and V
DD
SS
.
DD
DD
DD
DD
SS
DD
, 2/3 V
. The Bias 3
and V
1/3 V
2/3 V
)
V
V
DD
SS
DD
DD
DD
DD
)