Functional Description - Microchip Technology megaAVR 0 Series Manual

Figure 19-3. Timer/Counter Clock Logic
CLK_PER
CKSEL
EVACT
CNTEI
19.2.2 Signal Description
Signal
WOn
19.3

Functional Description

19.3.1 Definitions
The following definitions are used throughout the documentation:
Table 19-1. Timer/Counter Definitions
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.
UPDATE The update condition is met when the timer/counter reaches BOTTOM or TOP, depending on
the Waveform Generator mode.
CNT Counter register value.
CMP Compare register value.
In general, the term timer is used when the timer/counter is counting periodic clock ticks. The term
counter is used when the input signal has sporadic or irregular ticks.
19.3.2 Initialization
To start using the timer/counter in a basic mode, follow these steps:
• Write a TOP value to the Period register (TCAn.PER)
• Enable the peripheral by writing a '1' to the ENABLE bit in the Control A register (TCAn.CTRLA).
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2018 Microchip Technology Inc.
Prescaler
(Encoding)
Description
Digital output
Datasheet Preliminary
megaAVR
16-bit Timer/Counter Type A (TCA)
Event System
event
CLK_TCA
Type
Waveform output
®
0-Series
CNT
DS40002015A-page 187