PIC16F737-I/SP Microchip Technology Inc., PIC16F737-I/SP Datasheet - Page 83

• Manufacturer Part Number: PIC16F737-I/SP
• Description: 28 PIN, 7 KB FLASH, 368 RAM, 25 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F737-I/SP

• A/d Inputs: 5-Channel, 8-Bit
• Cpu Speed: 5 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 25
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin SPDIP
• Programmable Memory: 7K Bytes
• Ram Size: 192 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

7.6
A crystal oscillator circuit is built between pins T1OSI
(input) and T1OSO (amplifier output). It is enabled by
setting control bit, T1OSCEN (T1CON<3>). The oscil-
lator is a low-power oscillator, rated up to 32.768 kHz.
It will continue to run during all power-managed modes.
It is primarily intended for a 32 kHz crystal. The circuit
for a typical LP oscillator is shown in Figure 7-3.
Table 7-1 shows the capacitor selection for the Timer1
oscillator.
The user must provide a software time delay to ensure
proper oscillator start-up.
FIGURE 7-3:
TABLE 7-1:
 2004 Microchip Technology Inc.
Osc Type
Note:
Note 1: Microchip suggests this value as a starting
LP
33 pF
33 pF
C2
C1
2: Higher capacitance increases the stability
3: Since each resonator/crystal has its own
4: Capacitor values are for design guidance
Timer1 Oscillator
See the Notes with Table 7-1 for additional
information about capacitor selection.
point in validating the oscillator circuit.
of the oscillator but also increases the
start-up time.
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate
components.
only.
XTAL
32.768 kHz
32 kHz
Freq
CAPACITOR SELECTION FOR
THE TIMER1 OSCILLATOR
EXTERNAL
COMPONENTS FOR THE
TIMER1 LP OSCILLATOR
values
T1OSI
T1OSO
33 pF
C1
PIC16F7X7
of
33 pF
external
C2
7.7
The Timer1 oscillator circuit draws very little power
during operation. Due to the low-power nature of the
oscillator, it may also be sensitive to rapidly changing
signals in close proximity.
The oscillator circuit, shown in Figure 7-3, should be
located as close as possible to the microcontroller.
There should be no circuits passing within the oscillator
circuit boundaries other than V
If a high-speed circuit must be located near the oscilla-
tor, a grounded guard ring around the oscillator circuit,
as shown in Figure 7-4, may be helpful when used on
a single sided PCB or in addition to a ground plane.
FIGURE 7-4:
7.8
If the CCP1 module is configured in Compare mode to
generate
(CCP1M3:CCP1M0 = 1011), the signal will reset
Timer1 and start an A/D conversion (if the A/D module
is enabled).
Timer1 must be configured for either Timer or Synchro-
nized Counter mode to take advantage of this feature.
If Timer1 is running in Asynchronous Counter mode,
this Reset operation may not work.
In the event that a write to Timer1 coincides with a
special event trigger from CCP1, the write will take
precedence.
In this mode of operation, the CCPR1H:CCPR1L
register pair effectively becomes the period register for
Timer1.
Note:
Timer1 Oscillator Layout
Considerations
Resetting Timer1 Using a CCP
Trigger Output
The special event triggers from the CCP1
module will not set interrupt flag bit,
TMR1IF (PIR1<0>).
a
“special
OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
PIC16F7X7
event
SS
OSC1
RC0
V
OSC2
RC1
RC2
or V
SS
DS30498C-page 81
trigger”
DD
.
signal