PIC18F4450T-I/ML【PDF 97/241 页】IC PIC MCU FLASH 8KX16 44QFN

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录3872

93页 94页 95页 96页 [97页]98页 99页 100页 101页

186

XMEGA A [MANUAL]

8077I–AVR–11/2012

16.

Hi-Res – High-Resolution Extension

16.1

Features

Increases waveform generator resolution up to 8x (3 bits)

Supports frequency, single-slope PWM, and dual-slope PWM generation

Supports the AWeX when this is used for the same timer/counter

16.2

Overview

The high-resolution (hi-res) extension can be used to increase the resolution of the waveform generation output

from a timer/counter by four or eight. It can be used for a timer/counter doing frequency, single-slope PWM, or

dual-slope PWM generation. It can also be used with the AWeX if this is used for the same timer/counter.

The hi-res extension uses the peripheral 4x clock (ClkPER4). The system clock prescalers must be configured so the

peripheral 4x clock frequency is four times higher than the peripheral and CPU clock frequency when the hi-res

extension is enabled. Refer to “System Clock Selection and Prescalers” on page 83 for more details.

Figure 16-1. Timer/counter operation with hi-res extension enabled.

When the hi-res extension is enabled, the timer/counter must run from a non-prescaled peripheral clock. The

timer/counter will ignore its two least-significant bits (lsb) in the counter, and counts by four for each peripheral clock

cycle. Overflow/underflow and compare match of the 14 most-significant bits (msb) is done in the timer/counter. Count

and compare of the two lsb is handled and compared in the hi-res extension running from the peripheral 4x clock.

The two lsb of the timer/counter period register must be set to zero to ensure correct operation. If the count register is

read from the application code, the two lsb will always be read as zero, since the timer/counter run from the peripheral

clock. The two lsb are also ignored when generating events.

When the hi-res plus feature is enabled, the function is the same as with the hi-res extension, but the resolution will

increase by eight instead of four. This also means that the 3 lsb are handled by the hi-res extension instead of 2 lsb, as

when only hi-res is enabled. The extra resolution is achieved by counting on both edges of the peripheral 4x clock.

The hi-res extension will not output any pulse shorter than one peripheral clock cycle; i.e., a compare value lower than

four will have no visible output.

CNT[15:2]

HiRes

CCxBUF[15:0]

= 0

"match"

PER[15:2]

Waveform

Generation

TOP

BOTTOM

Time /Counter

CCx[15:2]

[1:0]

AWeX

Fault

Protection

Dead - Time

Insertion

Pattern

Generation

clkPER

clkPER4

Pxn

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式