
187
XMEGA A [MANUAL]
8077I–AVR–11/2012
16.3
Register Description
16.3.1 CTRLA – Control register A
Bit 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always write these bits to zero
when this register is written.
Bit 2 – HRPLUS: High Resolution Plus
Setting this bit enables high resolution plus. Hi-res plus is the same as hi-res, but will increase the resolution by eight (3
bits) instead of four.
The extra resolution is achieved by operating at both edges of the peripheral 4x clock.
Bit 1:0 – HREN[1:0]: High Resolution Enable
These bits enables the high-resolution mode for a timer/counter according to
Table 16-1.
Setting one or both HREN bits will enable high-resolution waveform generation output for the entire general purpose I/O
port. This means that both timer/counters connected to the same port must enable hi-res if both are used for generating
PWM or FRQ output on pins.
Table 16-1. High resolution enable.
16.4
Register Summary
Bit
7
65
432
10
+0x00
–
HRPLUS
HREN[1:0]
Read/Write
R
R/W
Initial Value
0
00
000
00
HREN[1:0]
High resolution enabled
00
None
01
Timer/counter 0
10
Timer/counter 1
11
Both timer/counters
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page
+0x00
CTRLA
–
HRPLUS
HREN[1:0]