PIC16F628A-I/P Microchip Technology, PIC16F628A-I/P Datasheet - Page 49

• Manufacturer Part Number: PIC16F628A-I/P
• Description: IC MCU FLASH 2KX14 EEPROM 18DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F628A-I/P

• Program Memory Type: FLASH
• Program Memory Size: 3.5KB (2K x 14)
• Package / Case: 18-DIP (0.300", 7.62mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 16
• Eeprom Size: 128 x 8
• Ram Size: 224 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 224 B
• Interface Type: SCI/USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 16
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163014, DM164120-4
• Minimum Operating Temperature: - 40 C
• Package: 18PDIP
• Device Core: PIC
• Family Name: PIC16
• Maximum Speed: 20 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: I3DBF648 - BOARD DAUGHTER ICEPIC3AC162053 - HEADER INTERFACE ICD,ICD2 18DIPACICE0202 - ADAPTER MPLABICE 18P 300 MILAC164010 - MODULE SKT PROMATEII DIP/SOIC
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

6.3.1
The prescaler assignment is fully under software
control (i.e., it can be changed “on-the-fly” during
program execution). Use the instruction sequences
shown in Example 6-1 when changing the prescaler
assignment from Timer0 to WDT, to avoid an
unintended device Reset.
EXAMPLE 6-1:
TABLE 6-1:
© 2009 Microchip Technology Inc.
01h, 101h
0Bh, 8Bh,
10Bh, 18Bh
81h, 181h
85h
Legend:
Note 1:
BCF
CLRWDT
CLRF
BSF
MOVLW
MOVWF
CLRWDT
MOVLW
MOVWF
BCF
Address
STATUS, RP0
TMR0
STATUS, RP0
'00101111’b
OPTION_REG
'00101xxx’b
OPTION_REG
STATUS, RP0
- = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used for Timer0.
Option is referred by OPTION_REG in MPLAB
SWITCHING PRESCALER
ASSIGNMENT
TMR0
INTCON
OPTION
TRISA
Name
REGISTERS ASSOCIATED WITH TIMER0
(2)
CHANGING PRESCALER
(TIMER0 → WDT)
Timer0 Module Register
TRISA7 TRISA6 TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 1111 1111 1111 1111
RBPU
Bit 7
GIE
;Skip if already in
;Bank 0
;Clear WDT
;Clear TMR0 and
;Prescaler
;Bank 1
;These 3 lines
;(5, 6, 7)
;are required only
;if desired PS<2:0>
;are
;000 or 001
;Set Postscaler to
;desired WDT rate
;Return to Bank 0
INTEDG
PEIE
Bit 6
T0CS
Bit 5
T0IE
T0SE
INTE
Bit 4
®
IDE Software.
PIC16F627A/628A/648A
RBIE
Bit 3
PSA
To change prescaler from the WDT to the Timer0
module, use the sequence shown in Example 6-2. This
precaution must be taken even if the WDT is disabled.
EXAMPLE 6-2:
CLRWDT
BSF
MOVLW
MOVWF
BCF
Bit 2
T0IF
PS2
STATUS, RP0
b'xxxx0xxx’
OPTION_REG
STATUS, RP0
Bit 1
INTF
PS1
CHANGING PRESCALER
(WDT → TIMER0)
RBIF
Bit 0
PS0
;Clear WDT and
;prescaler
;Select TMR0, new
;prescale value and
;clock source
xxxx xxxx uuuu uuuu
0000 000x 0000 000u
1111 1111 1111 1111
Value on
POR
DS40044G-page 49
Value on
All Other
Resets