PIC16F54T-I/SO Microchip Technology, PIC16F54T-I/SO Datasheet - Page 38

• Manufacturer Part Number: PIC16F54T-I/SO
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,SOP,18PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F54T-I/SO

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Peripherals: POR, WDT
• Number Of I /o: 12
• Program Memory Size: 768B (512 x 12)
• Program Memory Type: FLASH
• Ram Size: 25 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 18-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 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