7 OSCILLATOR (OSC)
7-4
EPSON
S1C17704 TECHNICAL MANUAL
7.3 OSC1 Oscillator
The OSC3 oscillator generates the 32.768 kHz (Typ.) sub-clock. Normally, the OSC1 clock is used as the operating
clock for timers (clock timer, stopwatch timer, watchdog timer, and 8-bit OSC1 timer). Furthermore, it can be used
as the system clock instead of the OSC3 clock to reduce current consumption when high-speed processing is not
required.
The oscillator type is crystal oscillation.
Figure 7.3.1 shows the structure of the OSC1 oscillator circuit.
V
SS
V
SS
OSC2
OSC1
X'tal1
C
G1
SLEEP status
f
OSC1
Figure 7.3.1 OSC1 Oscillator Circuit
To configure a crystal oscillator, connect a crystal X’tal1 (Typ. 32.768 kHz) between the OSC1 and OSC1 pins, and
a trimmer capacitor C
G1
(0–25 pF) between the OSC1 and V
SS
.
Controlling the OSC1 oscillation on and off
Setting OSC1EN (D1/OSC_CTL register) to 0 causes the OSC1 oscillator circuit to stop; setting it to 1 causes
the OSC1 oscillator circuit to start oscillating. Also the OSC1 oscillator circuit stops when the S1C17 Core
enters SLEEP mode.
∗
OSC1EN
: OSC1 Enable Bit in the Oscillation Control (OSC_CTL) Register (D1/0x5061)
Stable oscillation wait time when OSC1 starts oscillating
The OSC1 oscillator circuit provides an oscillation stabilization-wait timer to prevent malfunctions caused by
an unstable clock immediately after the OSC1 oscillator starts oscillating such as when the power is turned
on, when the S1C17 Core is woken from SLEEP mode or when software turns the OSC1 oscillator circuit on.
The OSC1 clock supply to the system is disabled for 256 OSC1 clock cycles after the OSC1 oscillator starts
oscillating.
Содержание S1C17704
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Страница 156: ...11 16 BIT TIMERS T16 11 18 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
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