PIC16F884-E/P Microchip Technology, PIC16F884-E/P Datasheet - Page 10

• Manufacturer Part Number: PIC16F884-E/P
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,DIP,40PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F884-E/P

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 7KB (4K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: DVA18XP400 - DEVICE ADAPTER 18F4220 PDIP 40LD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIC16F88X
8. Module: Asynchronous Timer1
EXAMPLE 3:
DS80302F-page 10
Update:
This Errata supersedes Errata DS80233 and
DS80329.
When TImer1 is started or updated, the timer
needs to see a falling edge from the external clock
source before a rising edge can increment the
counter. If writes to TMR1H and TMR1L are not
completed while the external clock pulse is still
high, Timer1 will not count the first clock pulse
after the update.
When using an external crystal, the pulse width
from rising to falling edge is temperature
dependent and may decrease with temperature.
As a result, the timer may require an additional
oscillation to overflow.
Work around
Switching to the HFINTOSC after reloading, the
timer ensures the Timer1 will see a falling edge
before switching back to the external clock source.
Affected Silicon Revisions
PIC16F882
PIC16F883/PIC16F884
PIC16F886/PIC16F887
BTFSC
GOTO
BTFSS
GOTO
BCF
BSF
BCF
BSF
BCF
Critical Timing of code sequence for instructions following last write to TMR1L or TMR1H.
A0
A0
A2
X
X
X
TMR1L,0
$-1
TMR1L,0
$-1
T1CON,TMR1CS
TMR1H,7
T1CON,TMR1ON
T1CON,TMR1CS
T1CON,TMR1ON
;Timer has just incremented, 31 μs before next rising edge to
;complete reload
;Select HFINTOSC for Timer1
;Timer1 high byte 0x80
;Timer1 off
;Select external crystal
;Timer1 on
Due to the time from Timer1 overflow to the reload
being application specific, wait for the timer to
increment before beginning the reload sequence.
This ensures the timer does not miss a rising edge
during reload.
© 2009 Microchip Technology Inc.