PIC16F874-20/L Microchip Technology, PIC16F874-20/L Datasheet - Page 4

• Manufacturer Part Number: PIC16F874-20/L
• Description: IC MCU FLASH 4KX14 EE 44PLCC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F874-20/L

• Core Size: 8-Bit
• Program Memory Size: 7KB (4K 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: 128 x 8
• Ram Size: 192 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: 44-PLCC
• Controller Family/series: PIC16F
• No. Of I/o's: 33
• Eeprom Memory Size: 128Byte
• Ram Memory Size: 192Byte
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 192 B
• Interface Type: MSSP, PSP, USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 33
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163022, DV164120
• Minimum Operating Temperature: 0 C
• On-chip Adc: 10 bit, 8 Channel
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC164309 - MODULE SKT FOR PM3 44PLCC444-1001 - DEMO BOARD FOR PICMICRO MCUDVA16XL441 - ADAPTER DEVICE ICE 44PLCC309-1040 - ADAPTER 44-PLCC ZIF TO 40-DIP309-1039 - ADAPTER 44-PLCC TO 40-DIPDV007003 - PROGRAMMER UNIVERSAL PROMATE II
• Lead Free Status / Rohs Status: Details

TIMER1 MODULE
EXAMPLE 2:
EXAMPLE 3:
DS80329B-page 4
HIntVector code 0x0008
HighISR:
;
;
RTCisr:
; If TMR1 update can be completed before clock pulse
; goes low, start update here
Update:
NextISR:
retfieFAST
goto
btfss
goto
Insert the next 4 lines of code when TMR1 can not
be reliably updated before clock pulse goes low
btfsc
bra
btfss
bra
bsf
bcf
incf
retfie FAST
....
BTFSC
GOTO
BTFSS
GOTO
BCF
MOVF
ADDWF
BTFSC
INCF
MOVF
MOVWF
MOVF
MOVW
BCF
BSF
BSF
Critical Timing of code sequence for instructions.
HighISR
code
PIR1,TMR1IF
NextISR
TMR1L,0
$-2
TMR1L,0
$-2
TMR1H,7
PIR1,TMR1IF
Seconds,F
T1CON, TMR1CS
TMR1, W
TMR1_Reload_lo, F
STATUS, C
TMR1_Reload_hi, F
TMR1_Reload_hi, W
TMR1H
TMR1_Reload_lo, W
TMR1L
T1CON, TMR1ON
T1CON, TMR1CS
T1CON, TMR1ON
TMR1L, 0
$-1
TMR1L, 0
$-1
PIC12/14/16/17 CODE EXAMPLE FOR OVERFLOW PERIODS OTHER THAN 1
SECOND OR USING AN OSCILLATOR OTHER THAN 32.768 kHZ
PIC18 HIGH-PRIORITY INTERRUPT SERVICE ROUTINE
;
;
;
;
;
;
;
;
;
;
;
;
;
;
(3-4Tcy), fixed interrupt latency
(3Tcy) jump to high priority ISR code
unprotected code space
(1Tcy) TMR1 overflow?
(2Tcy) No, check another interrupt source
wait for TMR1L<0> to become clear
may already be clear (loops for 0 to 30.5us)
wait for TMR1L<0> to become set
(loops for 30.5us)
reload for next 1 second overflow
clear flag
record second
Another interrupt source...
code for other interrupts, if needed
;Select system clock for Timer1.
;Sample low byte of Timer1 before increments.
;Add reload value for low byte
;if this generates a carry then
;modify the reload value for the high byte.
;Reload Timer1 high byte.
;Reload Timer1 low byte.
;Timer1 off.
;Select external crystal.
;Timer1 on.
;Timer has just incremented, 31μs before next rising
edge to complete reload.
 2010 Microchip Technology Inc.