PIC16F688-E/ML Microchip Technology, PIC16F688-E/ML Datasheet - Page 48
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PIC16F688-E/ML
Manufacturer Part Number
PIC16F688-E/ML
Description
IC PIC MCU FLASH 4KX14 16QFN
Manufacturer
Microchip Technology
Series
PIC® 16Fr
Datasheets
1.PIC16F616T-ISL.pdf
(8 pages)
2.PIC16F688T-ISL.pdf
(204 pages)
3.PIC16F688T-ISL.pdf
(6 pages)
4.PIC16F688T-ISL.pdf
(4 pages)
5.PIC16F688T-ISL.pdf
(688 pages)
Specifications of PIC16F688-E/ML
Core Size
8-Bit
Program Memory Size
7KB (4K x 14)
Core Processor
PIC
Speed
20MHz
Connectivity
UART/USART
Peripherals
Brown-out Detect/Reset, POR, WDT
Number Of I /o
12
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 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 125°C
Package / Case
16-QFN
Controller Family/series
PIC16F
No. Of I/o's
12
Eeprom Memory Size
256Byte
Ram Memory Size
256Byte
Cpu Speed
20MHz
No. Of Timers
2
Processor Series
PIC16F
Core
PIC
Data Bus Width
8 bit
Data Ram Size
256 B
Interface Type
EUSART, RS- 232, SCI, USB
Maximum Clock Frequency
20 MHz
Number Of Programmable I/os
12
Number Of Timers
2
Maximum Operating Temperature
+ 125 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, DM163014, DM164120-4
Minimum Operating Temperature
- 40 C
On-chip Adc
10 bit, 8 Channel
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
For Use With
AC164324 - MODULE SKT FOR MPLAB 8DFN/16QFNXLT16QFN1 - SOCKET TRANSITION 14DIP TO 16QFNAC162061 - HEADER INTRFC MPLAB ICD2 20PINAC162056 - HEADER INTERFACE ICD2 16F688
Lead Free Status / Rohs Status
Details
PIC16F688
5.1.3
A single software programmable prescaler is available
for use with either Timer0 or the Watchdog Timer
(WDT), but not both simultaneously. The prescaler
assignment is controlled by the PSA bit of the OPTION
register. To assign the prescaler to Timer0, the PSA bit
must be cleared to a ‘0’.
There are 8 prescaler options for the Timer0 module
ranging from 1:2 to 1:256. The prescale values are
selectable via the PS<2:0> bits of the OPTION register.
In order to have a 1:1 prescaler value for the Timer0
module, the prescaler must be assigned to the WDT
module.
The prescaler is not readable or writable. When
assigned to the Timer0 module, all instructions writing to
the TMR0 register will clear the prescaler.
When the prescaler is assigned to WDT, a CLRWDT
instruction will clear the prescaler along with the WDT.
5.1.3.1
As a result of having the prescaler assigned to either
Timer0 or the WDT, it is possible to generate an
unintended device Reset when switching prescaler
values. When changing the prescaler assignment from
Timer0 to the WDT module, the instruction sequence
shown in Example 5-1, must be executed.
EXAMPLE 5-1:
DS41203E-page 46
BANKSEL
CLRWDT
CLRF
BANKSEL
BSF
CLRWDT
MOVLW
ANDWF
IORLW
MOVWF
SOFTWARE PROGRAMMABLE
PRESCALER
TMR0
TMR0
OPTION_REG
OPTION_REG,PSA ;Select WDT
b’11111000’
OPTION_REG,W
b’00000101’
OPTION_REG
Switching Prescaler Between
Timer0 and WDT Modules
CHANGING PRESCALER
(TIMER0 → WDT)
;
;Clear WDT
;Clear TMR0 and
;prescaler
;
;
;
;Mask prescaler
;bits
;Set WDT prescaler
;to 1:32
When changing the prescaler assignment from the
WDT to the Timer0 module, the following instruction
sequence must be executed (see Example 5-2).
EXAMPLE 5-2:
5.1.4
Timer0 will generate an interrupt when the TMR0
register overflows from FFh to 00h. The T0IF interrupt
flag bit of the INTCON register is set every time the
TMR0 register overflows, regardless of whether or not
the Timer0 interrupt is enabled. The T0IF bit must be
cleared in software. The Timer0 interrupt enable is the
T0IE bit of the INTCON register.
5.1.5
When Timer0 is in Counter mode, the synchronization
of the T0CKI input and the Timer0 register is accom-
plished by sampling the prescaler output on the Q2 and
Q4 cycles of the internal phase clocks. Therefore, the
high and low periods of the external clock source must
meet
Section 14.0 “Electrical Specifications”.
CLRWDT
BANKSEL OPTION_REG
MOVLW
ANDWF
IORLW
MOVWF
Note:
the
b’11110000’ ;Mask TMR0 select and
OPTION_REG,W ;prescaler bits
b’00000011’ ;Set prescale to 1:16
OPTION_REG
TIMER0 INTERRUPT
The Timer0 interrupt cannot wake the
processor from Sleep since the timer is
frozen during Sleep.
USING TIMER0 WITH AN
EXTERNAL CLOCK
timing
requirements
CHANGING PRESCALER
(WDT → TIMER0)
© 2009 Microchip Technology Inc.
;Clear WDT and
;prescaler
;
;
as
shown
in