PIC16F785-I/P Microchip Technology Inc., PIC16F785-I/P Datasheet - Page 54

• Manufacturer Part Number: PIC16F785-I/P
• Description: MCU, 8-Bit, 2KW Flash, 128 RAM, 18 I/O, DIP-20
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F785-I/P

• A/d Inputs: 12-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 17
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 20-pin PDIP
• Programmable Memory: 3.5K 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

PIC16F785/HV785
6.1
Timer1 can operate in one of three modes:
• 16-bit Timer with prescaler
• 16-bit Synchronous counter
• 16-bit Asynchronous counter
In Timer mode, Timer1 is incremented on every instruc-
tion cycle. In Counter mode, Timer1 is incremented on
the rising edge of the external clock input T1CKI. In
addition, the Counter mode clock can be synchronized
to
asynchronously.
In Counter and Timer modules, the counter/timer clock
can be gated by the Timer1 gate, which can be
selected as either the T1G pin or Comparator 2 output.
If an external clock oscillator is needed (and the
microcontroller is using the LP oscillator or INTOSC
without CLKOUT), Timer1 can use the LP oscillator as
a clock source.
6.2
The Timer1 register pair (TMR1H:TMR1L) increments
to FFFFh and rolls over to 0000h. When Timer1 rolls
over, the Timer1 interrupt flag bit (PIR1<0>) is set. To
enable the interrupt on rollover, you must set these bits:
• Timer1 Interrupt Enable bit (PIE1<0>)
• PEIE bit (INTCON<6>)
• GIE bit (INTCON<7>)
FIGURE 6-2:
DS41249D-page 52
Note:
T1CKI = 1
when TMR1
Enabled
T1CKI = 0
when TMR1
Enabled
Note 1:
the
Timer1 Modes of Operation
Timer1 Interrupt
microcontroller
2:
In Counter mode, a falling edge must be
registered by the counter prior to the first
incrementing rising edge after any one or
more of the following conditions.
• Timer1 enabled after POR Reset
• Write to TMR1H or TMR1L
• Timer1 is disabled (TMR1ON = 0)
when T1CKI is high then Timer1 is
enabled (TMR1ON = 1) when T1CKI
is low. See Figure 6-2.
Arrows indicate counter increments.
See note box in Section 6.1 “Timer1 Modes of Operation”.
TIMER1 INCREMENTING EDGE
system
clock
or
Preliminary
run
The interrupt is cleared by clearing the TMR1IF in the
Interrupt Service Routine.
6.3
Timer1 has four prescaler options allowing 1, 2, 4 or 8
divisions of the clock input. The T1CKPS bits
(T1CON<5:4>) control the prescale counter. The
prescale counter is not directly readable or writable;
however, the prescaler counter is cleared upon a write
to TMR1H or TMR1L.
6.4
Timer1 gate source is software configurable to be T1G
pin or the output of Comparator 2. This allows the
device to directly time external events using T1G or
analog events using Comparator 2. See CM2CON1
(Register 9-3) for selecting the Timer1 gate source.
This feature can simplify the software for a Delta-Sigma
A/D Converter and many other applications. For more
information on Delta-Sigma A/D Converters, see the
Microchip web site (www.microchip.com).
Timer1 gate can be inverted using the T1GINV bit
(T1CON<7>), whether it originates from the T1G pin or
Comparator 2 output. This configures Timer1 to
measure either the active high or active low time
between events.
Note:
Note:
Timer1 Prescaler
Timer1 Gate
The TMR1H:TMR1L register pair and the
TMR1IF bit should be cleared before
enabling interrupts.
TMR1GE bit (T1CON<6>) must be set to
use either T1G or C2OUT as the Timer1
gate source. See Register 9-3 for more
information on selecting the Timer1 gate
source.
© 2006 Microchip Technology Inc.