DSPIC30F4012-20I/SO【PDF 3/238 页】IC DSPIC MCU/DSP 48K 28SOIC

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3828

1页 2页 [3页]4页 5页 6页 7页

dsPIC30F4011/4012

DS70135G-page 100

2010 Microchip Technology Inc.

15.1.4

DOUBLE UPDATE MODE

In the Double Update mode (PTMOD<1:0> = 11), an

interrupt event is generated each time the PTMR regis-

ter is equal to zero, as well as each time a period match

occurs. The postscaler selection bits have no effect in

this mode of the timer.

The Double Update mode provides two additional func-

tions to the user. First, the control loop bandwidth is

doubled because the PWM duty cycles can be

updated, twice per period. Second, asymmetrical

center-aligned PWM waveforms can be generated

which are useful for minimizing output waveform

distortion in certain motor control applications.

15.1.5

PWM TIME BASE PRESCALER

The input clock to PTMR (FOSC/4) has prescaler

options of 1:1, 1:4, 1:16 or 1:64, selected by control

bits, PTCKPS<1:0>, in the PTCON SFR. The prescaler

counter is cleared when any of the following occurs:

A write to the PTMR register

A write to the PTCON register

Any device Reset

The PTMR register is not cleared when PTCON is

written.

15.1.6

PWM TIME BASE POSTSCALER

The match output of PTMR can optionally be post-

scaled through a 4-bit postscaler (which gives a 1:1 to

1:16 scaling).

The postscaler counter is cleared when any of the

following occurs:

A write to the PTMR register

A write to the PTCON register

Any device Reset

The PTMR register is not cleared when the PTCON

15.2

PWM Period

PTPER is a 15-bit register and is used to set the

counting period for the PWM time base. PTPER is a

double-buffered register. The PTPER buffer contents

are loaded into the PTPER register at the following

instants:

Free-Running and Single-Shot modes: When the

PTMR register is reset to zero after a match with

the PTPER register.

Continuous Up/Down Count modes: When the

PTMR register is zero.

The value held in the PTPER buffer is automatically

loaded into the PTPER register when the PWM time

base is disabled (PTEN = 0).

The

PWM

period

can

determined

using

Equation 15-1:

EQUATION 15-1:

PWM PERIOD

If the PWM time base is configured for one of the

Continuous Up/Down Count modes, the PWM period is

provided by Equation 15-2.

EQUATION 15-2:

PWM PERIOD

(CENTER-ALIGNED

MODE)

The maximum resolution (in bits) for a given device

oscillator and PWM frequency can be determined using

Equation 15-3:

EQUATION 15-3:

PWM RESOLUTION

Note:

Programming a value of 0x0001 in the

Period

could

generate

continuous interrupt pulse, and hence,

must be avoided.

TPWM = TCY

(PTPER + 1) PTMR Prescale Value

TPWM = TCY

2 PTPER + 1) PTMR Prescale Value

Resolution =

log (2

TPWM/TCY)

log (2)

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