Datasheet

© 2006 Microchip Technology Inc. DS70117F-page 71
dsPIC30F6011/6012/6013/6014
9.4 Timer Interrupt
The 16-bit timer has the ability to generate an interrupt on
period match. When the timer count matches the Period
register, the T1IF bit is asserted and an interrupt will be
generated if enabled. The T1IF bit must be cleared in
software. The timer interrupt flag, T1IF, is located in the
IFS0 Control register in the interrupt controller.
When the Gated Time Accumulation mode is enabled,
an interrupt will also be generated on the falling edge of
the gate signal (at the end of the accumulation cycle).
Enabling an interrupt is accomplished via the respec-
tive timer interrupt enable bit, T1IE. The timer interrupt
enable bit is located in the IEC0 Control register in the
interrupt controller.
9.5 Real-Time Clock
Timer1, when operating in Real-Time Clock (RTC)
mode, provides time of day and event time-stamping
capabilities. Key operational features of the RTC are:
• Operation from 32 kHz LP oscillator
• 8-bit prescaler
• Low power
• Real-Time Clock interrupts
These Operating modes are determined by setting the
appropriate bit(s) in the T1CON Control register.
FIGURE 9-2: RECOMMENDED
COMPONENTS FOR
TIMER1 LP OSCILLATOR
RTC
9.5.1 RTC OSCILLATOR OPERATION
When the TON = 1, TCS = 1 and TGATE = 0, the timer
increments on the rising edge of the 32 kHz LP oscilla-
tor output signal, up to the value specified in the Period
register and is then Reset to ‘0’.
The TSYNC bit must be asserted to a logic ‘0’
(Asynchronous mode) for correct operation.
Enabling LPOSCEN (OSCCON<1>) will disable the
normal Timer and Counter modes and enable a timer
carry-out wake-up event.
When the CPU enters Sleep mode, the RTC will con-
tinue to operate provided the 32 kHz external crystal
oscillator is active and the control bits have not been
changed. The TSIDL bit should be cleared to ‘0’ in
order for RTC to continue operation in Idle mode.
9.5.2 RTC INTERRUPTS
When an interrupt event occurs, the respective interrupt
flag, T1IF, is asserted and an interrupt will be generated
if enabled. The T1IF bit must be cleared in software. The
respective Timer interrupt flag, T1IF, is located in the
IFS0 Status register in the interrupt controller.
Enabling an interrupt is accomplished via the respec-
tive timer interrupt enable bit, T1IE. The timer interrupt
enable bit is located in the IEC0 Control register in the
interrupt controller.
SOSCI
SOSCO
R
C1
C2
dsPIC30FXXXX
32.768 kHz
XTAL
C1 = C2 = 18 pF; R = 100K