
SNOS535I – OCTOBER 2000 – REVISED MARCH 2013
Table 5-14. Timer Operating Modes
Interrupt A Source Interrupt B Source
Timer Counts
Mode
TxC3
TxC2
TxC1
Description
On
1
0
1
PWM: TxA Toggle
Autoreload RA
Autoreload RB
tC or MCLK
1
0
PWM: No TxA Toggle
Autoreload RA
Autoreload RB
tC or MCLK
0
External Event Counter
Timer Underflow
Pos. TxB Edge
TxA Pos. Edge
2
0
1
External Event Counter
Timer Underflow
Pos. TxB Edge
TxA Neg. Edge
0
1
0
Captures:
Pos. TxA Edge
Pos. TxB Edge
tC or MCLK
TxA Pos. Edge
or Timer
TxB Pos. Edge
Underflow
1
0
Captures:
Pos. TxA
Neg. TxB
tC or MCLK
TxA Pos. Edge
Edge or Timer
Edge
TxB Neg. Edge
Underflow
3
0
1
Captures:
Neg. TxA
Pos. TxB
tC or MCLK
TxA Neg. Edge
Edge or Timer
Edge
TxB Pos. Edge
Underflow
1
Captures:
Neg. TxA
Neg. TxB
tC or MCLK
TxA Neg. Edge
Edge or Timer
Edge
TxB Neg. Edge
Underflow
5.12 Power Saving Features
Today, the proliferation of battery-operated applications has placed new demands on designers to drive
power consumption down. Battery operated systems are not the only type of applications demanding low
power. The power budget constraints are also imposed on those consumer/industrial applications where
well regulated and expensive power supply costs cannot be tolerated. Such applications rely on low cost
and low power supply voltage derived directly from the “mains” by using voltage rectifier and passive
components. Low power is demanded even in automotive applications, due to increased vehicle
electronics content. This is required to ease the burden from the car battery. Low power 8-bit
microcontrollers supply the smarts to control battery-operated, consumer/industrial, and automotive
applications.
The device offers system designers a variety of low-power consumption features that enable them to meet
the demanding requirements of today's increasing range of low-power applications. These features include
low voltage operation, low current drain, and power saving features such as HALT, IDLE, and Multi-Input
Wake-Up (MIWU).
This device supports three operating modes, each of which have two power save modes of operation. The
three operating modes are: High Speed, Dual Clock, and Low Speed. Within each operating mode, the
two power save modes are: HALT and IDLE. In the HALT mode of operation, all microcontroller activities
are stopped and power consumption is reduced to a very low level. In this device, the HALT mode is
enabled and disabled by a bit in the Option register. The IDLE mode is similar to the HALT mode, except
that certain sections of the device continue to operate, such as: the on-board oscillator, the IDLE Timer
(Timer T0), and the Clock Monitor. This allows real time to be maintained. During power save modes of
operation, all on board RAM, registers, I/O states and timers (with the exception of T0) are unaltered.
Two oscillators are used to support the three different operating modes. The high speed oscillator refers to
the oscillator connected to CKI and the low speed oscillator refers to the 32 kHz oscillator connected to
pins L0 & L1. When using L0 and L1 for the low speed oscillator, the user must ensure that the L0 and L1
pins are configured for hi-Z input, L1 is not using CKX on the USART, and Multi-Input Wake-up for these
pins is disabled.
48
Functional Description
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