Datasheet

152
XMEGA B [DATASHEET]
8291B–AVR–01/2013
Some timer/counters have extensions to enable more specialized waveform and frequency generation. The advanced
waveform extension (AWeX) is intended for motor control and other power control applications. It enables low- and high-
side output with dead-time insertion, as well as fault protection for disabling and shutting down external drivers. It can
also generate a synchronized bit pattern across the port pins. The high-resolution (hi-res) extension can be used to
increase the waveform output resolution by four or eight times by using an internal clock source running up to four times
faster than the peripheral clock.
A block diagram of the 16-bit timer/counter with extensions and closely related peripheral modules (in grey) is shown in
Figure 13-1 on page 152.
Figure 13-1. 16-bit timer/counter and closely related peripherals.
13.2.1 Definitions
The following definitions are used throughout the documentation:
Table 13-1. Timer/counter definitions
In general, the term “timer” is used when the timer/counter clock control is handled by an internal source, and the term
“counter” is used when the clock control is handled externally (e.g. counting external events). When used for compare
operations, the CC channels are referred to as “compare channels.” When used for capture operations, the CC channels
are referred to as “capture channels.”
Name Description
BOTTOM The counter reaches BOTTOM when it becomes zero.
MAX The counter reaches MAXimum when it becomes all ones.
TOP
The counter reaches TOP when it becomes equal to the highest value in the count sequence. The TOP
value can be equal to the period (PER) or the compare channel A (CCA) register setting. This is selected
by the waveform generator mode.
UPDATE
The timer/counter signals an update when it reaches BOTTOM or TOP, depending on the waveform
generator mode.