PIC16F877-20/P Microchip Technology, PIC16F877-20/P Datasheet - Page 464

• Manufacturer Part Number: PIC16F877-20/P
• Description: IC MCU FLASH 8KX14 EE 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F877-20/P

• Core Size: 8-Bit
• Program Memory Size: 14KB (8K x 14)
• Core Processor: PIC
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 33
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 368 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Controller Family/series: PIC16F
• No. Of I/o's: 33
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 368Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 444-1001 - DEMO BOARD FOR PICMICRO MCU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PICmicro MID-RANGE MCU FAMILY
25.3
25.3.1
DS31025A-page 25-6
crystal oscillator
Nominal F
TMR1 32 kHz
Internal RC oscillator
F
OSC
Timing Clock Source Selection
LCD Timing
RC
= 14 kHz
256
The LCD module has 3 possible clock source inputs and supports static, 1/2, 1/3, and 1/4 multi-
plexing.
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.
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 processor is in sleep. It is assumed
that the frequency provided 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 register is used to set the LCD frame clock rate.
The clock sources are selected with bits CS1:CS0 (LCDCON<3:2>). Refer to
details of the register programming.
Figure 25-2:
CS1:CS0
LCD Clock Generation
2
4
LMUX1:LMUX0
Static
1/2
1/3
1/4
used for device low frequency or sleep operation
used for device low frequency or sleep operation
4-bit Programmable
LCDPS<3:0>
Prescaler
data bus
internal
32
1997 Microchip Technology Inc.
LMUX1:LMUX0
Ring Counter
1,2,3,4
Figure 25-1
for