PIC16F57-I/P Microchip Technology, PIC16F57-I/P Datasheet - Page 38

• Manufacturer Part Number: PIC16F57-I/P
• Description: IC MCU FLASH 2KX12 28DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F57-I/P

• Program Memory Type: FLASH
• Program Memory Size: 3KB (2K x 12)
• Package / Case: 28-DIP (0.600", 15.24mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Peripherals: POR, WDT
• Number Of I /o: 20
• Ram Size: 72 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 72 B
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 20
• Number Of Timers: 1
• 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: DV164120, DV164101, ICE2000
• Minimum Operating Temperature: - 40 C
• Data Rom Size: 2 K
• Height: 3.3 mm
• Length: 34.67 mm
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2 V
• Width: 7.24 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT28XP - SOCKET TRANSITION ICE 28DIPAC164001 - MODULE SKT PROMATEII 18/28DIP
• Eeprom Size: -
• Data Converters: -
• Connectivity: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC16F5X
7.2.1
The prescaler assignment is fully under software control
(i.e., it can be changed “on-the-fly” during program
execution). To avoid an unintended device Reset, the
following instruction sequence (Example 7-1) must be
executed when changing the prescaler assignment
from Timer0 to the WDT.
EXAMPLE 7-1:
FIGURE 7-5:
DS41213D-page 36
CLRWDT
CLRF
MOVLW
OPTION
CLRWDT
MOVLW
OPTION
Note 1:
TMR0
B'00xx1111’ ;Last 3 instructions
B'00xx1xxx’ ;Set Prescaler to
WDT Enable bit
T0CKI
SWITCHING PRESCALER
ASSIGNMENT
Watchdog
pin
Timer
T
CY
( = F
T0CS, T0SE, PSA PS<2:0> are bits in the Option register.
OSC
CHANGING PRESCALER
(TIMER0→WDT)
BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER
T0SE
;Clear WDT
;Clear TMR0 &
;in this example
;are required only if
;desired
;PS<2:0> are 000 or 001
;desired WDT rate
/4)
(1)
0
1
PSA
M
U
X
(1)
;Prescaler
0
1
T0CS
M
U
X
(1)
0
8-bit Prescaler
8-to-1 MUX
Time-Out
8
MUX
WDT
1
0
1
To change prescaler from the WDT to the Timer0
module, use the sequence shown in Example 7-2. This
sequence must be used even if the WDT is disabled. A
CLRWDT instruction should be executed before
switching the prescaler.
EXAMPLE 7-2:
PSA
CLRWDT
MOVLW
OPTION
M
U
X
(1)
PSA
(1)
B'xxxx0xxx' ;Select TMR0, new
PS<2:0>
Cycles
Sync
2
(1)
CHANGING PRESCALER
(WDT→TIMER0)
© 2007 Microchip Technology Inc.
;Clear WDT and
;prescaler
;prescale value and
;clock source
TMR0 reg
Data Bus
8