PIC16F818-I/P Microchip Technology Inc., PIC16F818-I/P Datasheet - Page 60

• Manufacturer Part Number: PIC16F818-I/P
• Description: 18 PIN, 1.75 KB FLASH, 128 RAM, 16 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F818-I/P

• A/d Inputs: 5-Channel, 10-Bit
• Cpu Speed: 5 MIPS
• Eeprom Memory: 128 Bytes
• Input Output: 16
• Interface: I2C/SPI
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 18-pin PDIP
• Programmable Memory: 1.75K Bytes
• Ram Size: 128 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC16F818/819
7.2
Timer mode is selected by clearing the TMR1CS
(T1CON<1>) bit. In this mode, the input clock to the
timer is F
(T1CON<2>), has no effect since the internal clock is
always in sync.
7.3
Timer1 may operate in Asynchronous or Synchronous
mode depending on the setting of the TMR1CS bit.
When Timer1 is being incremented via an external
source, increments occur on a rising edge. After Timer1
is enabled in Counter mode, the module must first have
a falling edge before the counter begins to increment.
FIGURE 7-1:
FIGURE 7-2:
DS39598E-page 58
T1CKI
(Default High)
T1CKI
(Default Low)
Note: Arrows indicate counter increments.
Note 1: When the T1OSCEN bit is cleared, the inverter is turned off. This eliminates power drain.
RB6/T1OSO/T1CKI/PGC
Timer1 Operation in Timer Mode
Timer1 Counter Operation
OSC
RB7/T1OSI/PGD
/4. The synchronize control bit, T1SYNC
Set Flag bit
TMR1IF on
Overflow
TIMER1 INCREMENTING EDGE
TIMER1 BLOCK DIAGRAM
TMR1H
T1OSC
TMR1
TMR1L
Oscillator
Enable
T1OSCEN
(1)
Internal
Clock
F
OSC
/4
TMR1ON
7.4
Counter mode is selected by setting bit TMR1CS. In
this mode, the timer increments on every rising edge of
clock input on pin RB7/T1OSI/PGD when bit
T1OSCEN is set, or on pin RB6/T1OSO/T1CKI/PGC
when bit T1OSCEN is cleared.
If T1SYNC is cleared, then the external clock input is
synchronized with internal phase clocks. The synchro-
nization is done after the prescaler stage. The
prescaler stage is an asynchronous ripple counter.
In this configuration, during Sleep mode, Timer1 will not
increment even if the external clock is present, since
the synchronization circuit is shut-off. The prescaler,
however, will continue to increment.
On/Off
TMR1CS
1
0
Timer1 Operation in Synchronized
Counter Mode
T1CKPS1:T1CKPS0
T1SYNC
Prescaler
1, 2, 4, 8
0
1
2
 2004 Microchip Technology Inc.
Synchronized
Clock Input
Synchronize
Q Clock
det