PIC12C672-10/SM Microchip Technology, PIC12C672-10/SM Datasheet - Page 185

• Manufacturer Part Number: PIC12C672-10/SM
• Description: IC MCU OTP 2KX14 A/D 8-SOIJ
• Manufacturer: Microchip Technology
• Series: PIC® 12Cr

Specifications of PIC12C672-10/SM

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 10MHz
• Peripherals: POR, WDT
• Number Of I /o: 5
• Program Memory Size: 3.5KB (2K x 14)
• Program Memory Type: OTP
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Data Converters: A/D 4x8b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 8-SOIC (5.3mm Width), 8-SOP, 8-SOEIAJ
• For Use With: XLT08SO-1 - SOCKET TRANSITION 8SOIC 150/208AC164312 - MODULE SKT FOR PM3 16SOICISPICR1 - ADAPTER IN-CIRCUIT PROGRAMMING309-1048 - ADAPTER 8-SOIC TO 8-DIP309-1047 - ADAPTER 8-SOIC TO 8-DIPAC124001 - MODULE SKT PROMATEII 8DIP/SOIC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Connectivity: -
• Other names: PIC12C672-10/SMR; PIC12C672-10/SMR

12.5
12.5.1
12.5.2
1997 Microchip Technology Inc.
External Clock Input Timing with Unsynchronized Clock
Reading and Writing Timer1 in Asynchronous Counter Mode
Timer1 Operation in Asynchronous Counter Mode
If T1SYNC (T1CON<2>) is set, the external clock input is not synchronized. The timer continues
to increment asynchronously to the internal phase clocks. The timer will continue to run during
SLEEP and can generate an interrupt on overflow which will wake-up the processor. However,
special precautions in software are needed to read/write the timer (Subsection
and Writing Timer1 in Asynchronous Counter
sleep, Timer1 can be used to implement a true real-time clock.
In asynchronous counter mode, Timer1 cannot be used as a time-base for capture or compare
operations.
If the T1SYNC control bit is set, the timer will increment completely asynchronously. The input
clock must meet certain minimum high time and low time requirements. Refer to the Device Data
Sheet Electrical Specifications Section, timing
Reading TMR1H or TMR1L while the timer is running from an external asynchronous clock, will
guarantee a valid read (taken care of in hardware). However, the user should keep in mind that
reading the 16-bit timer in two 8-bit values itself poses certain problems since the timer may
overflow between the reads.
For writes, it is recommended that the user simply stop the timer and write the desired values. A
write contention may occur by writing to the timer registers while the register is incrementing. This
may produce an unpredictable value in the timer register.
Reading the 16-bit value requires some care, since two separate reads are required to read the
entire 16-bits.
register.
Example 12-1:
04FFh
0500h
0501h
0502h
TMR1
Example 12-1
Reading 16-bit Register Issues
READ TMR1L
Store in TMPL
READ TMR1H
Store in TMPH
Action
shows why this may not be a straight forward read of the 16-bit
Sequence 1
TMPH:TMPL
05FFh
xxFFh
xxFFh
xxxxh
Section 12. Timer1
parameters
Mode”). Since the counter can operate in
45, 46, and 47.
READ TMR1H
Store in TMPH
READ TMR1L
Store in TMPL
Action
Sequence 2
DS31012A-page 12-5
12.5.2 “Reading
TMPH:TMPL
0401h
04xxh
04xxh
xxxxh
12