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| 型号： | KSZ8851-16MLL-EVAL |
| 厂商： | Micrel Inc |
| 文件页数： | 55/84页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION KSZ8851-16MLL |
| 产品培训模块： | KSZ8851 10/100 Embedded Controllers |
| 标准包装： | 1 |
| 系列： | LinkMD® |
| 主要目的： | 接口，以太网控制器（PHY 和 MAC） |
| 嵌入式： | 否 |
| 已用 IC / 零件： | KSZ8851-16MLL |
| 主要属性： | 1 个端口，100BASE-TX/10BASE-T |
| 次要属性： | 8/16 位接口，LinkMD 线缆诊断 |
| 已供物品： | 板，文档 |
| 产品目录页面： | 1081 (CN2011-ZH PDF) |
| 相关产品： | 576-3438-ND - IC CTLR MAC/PHY NON PCI 128PQFP 576-3253-ND - IC CTLR MAC/PHY NON-PCI 128-PQFP 576-3252-ND - IC CTLR MAC/PHY NON-PCI 48-LQFP |
| 其它名称： | 576-3292 |
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2002 Microchip Technology Inc.
DS30325B-page 57
PIC16F7X
8.5
PWM Mode (PWM)
In Pulse Width Modulation mode, the CCPx pin pro-
duces up to a 10-bit resolution PWM output. Since the
CCP1 pin is multiplexed with the PORTC data latch, the
TRISC<2> bit must be cleared to make the CCP1 pin
an output.
Figure 8-3 shows a simplified block diagram of the
CCP module in PWM mode.
For a step-by-step procedure on how to set up the CCP
module for PWM operation, see Section 8.5.3.
FIGURE 8-3:
SIMPLIFIED PWM BLOCK
DIAGRAM
A PWM output (Figure 8-4) has a time-base (period)
and a time that the output stays high (duty cycle). The
frequency of the PWM is the inverse of the period
(1/period).
FIGURE 8-4:
PWM OUTPUT
8.5.1
PWM PERIOD
The PWM period is specified by writing to the PR2
register. The PWM period can be calculated using the
following formula:
PWM period =
[(PR2) + 1] 4 TOSC
(TMR2 prescale value)
PWM frequency is defined as 1 / [PWM period].
When TMR2 is equal to PR2, the following three events
occur on the next increment cycle:
TMR2 is cleared
The CCP1 pin is set (exception: if PWM duty
cycle = 0%, the CCP1 pin will not be set)
The PWM duty cycle is latched from CCPR1L into
CCPR1H
8.5.2
PWM DUTY CYCLE
The PWM duty cycle is specified by writing to the
CCPR1L register and to the CCP1CON<5:4> bits. Up
to 10-bit resolution is available. The CCPR1L contains
the eight MSbs and the CCP1CON<5:4> contains the
two LSbs. This 10-bit value is represented by
CCPR1L:CCP1CON<5:4>. The following equation is
used to calculate the PWM duty cycle in time:
PWM duty cycle = (CCPR1L:CCP1CON<5:4>)
TOSC (TMR2 prescale value)
CCPR1L and CCP1CON<5:4> can be written to at any
time, but the duty cycle value is not latched into
CCPR1H until after a match between PR2 and TMR2
occurs (i.e., the period is complete). In PWM mode,
CCPR1H is a read only register.
The CCPR1H register and a 2-bit internal latch are
used to double buffer the PWM duty cycle. This double
buffering is essential for glitchless PWM operation.
When the CCPR1H and 2-bit latch match TMR2, con-
catenated with an internal 2-bit Q clock or 2 bits of the
TMR2 prescaler, the CCP1 pin is cleared.
The maximum PWM resolution (bits) for a given PWM
frequency is given by the formula:
Note:
Clearing the CCP1CON register will force
the CCP1 PWM output latch to the default
low level. This is not the PORTC I/O data
latch.
CCPR1L
CCPR1H (Slave)
Comparator
TMR2
Comparator
PR2
(1)
RQ
S
Duty Cycle Registers
CCP1CON<5:4>
Clear Timer,
CCP1 pin and
latch D.C.
TRISC<2>
RC2/CCP1
(Note 1)
Note 1: The 8-bit timer is concatenated with the 2-bit inter-
nal Q clock or the 2 bits of the prescaler to create the
10-bit time-base.
Period
Duty Cycle
TMR2 = PR2
TMR2 = Duty Cycle
TMR2 = PR2
TMR2
RESET
TMR2
RESET
Note:
The Timer2 postscaler (see Section 8.3) is
not used in the determination of the PWM
frequency. The postscaler could be used to
have a servo update rate at a different fre-
quency than the PWM output.
Note:
If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
log
(
FPWM
log(2)
FOSC
)
bits
=
Resolution
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相关代理商/技术参数 |
参数描述 |
|---|---|
| KSZ8851-16MLL-EVAL | 制造商:Micrel Inc 功能描述:BOARD EVALUATION FOR KSZ8851-16MLL |
| KSZ8851-16MLLI | 功能描述:以太网 IC 10/100BT Ethernet MAC + PHY with Generic (8, 16-bit) Bus Interface (I-Temp, Lead Free) RoHS:否 制造商:Micrel 产品:Ethernet Switches 收发器数量:2 数据速率:10 Mb/s, 100 Mb/s 电源电压-最大:1.25 V, 3.45 V 电源电压-最小:1.15 V, 3.15 V 最大工作温度:+ 85 C 封装 / 箱体:QFN-64 封装:Tray |
| KSZ8851-16MLLI TR | 功能描述:以太网 IC 10/100BT Ethernet MAC + PHY with Generic (8, 16-bit) Bus Interface (I-Temp, Lead Free) RoHS:否 制造商:Micrel 产品:Ethernet Switches 收发器数量:2 数据速率:10 Mb/s, 100 Mb/s 电源电压-最大:1.25 V, 3.45 V 电源电压-最小:1.15 V, 3.15 V 最大工作温度:+ 85 C 封装 / 箱体:QFN-64 封装:Tray |
| KSZ8851-16MLLJ | 功能描述:以太网 IC Single-Port Ethernet MAC Controller with 8/16-Bit Non-PCI Interface (125C support) RoHS:否 制造商:Micrel 产品:Ethernet Switches 收发器数量:2 数据速率:10 Mb/s, 100 Mb/s 电源电压-最大:1.25 V, 3.45 V 电源电压-最小:1.15 V, 3.15 V 最大工作温度:+ 85 C 封装 / 箱体:QFN-64 封装:Tray |
| KSZ8851-16MLLJ_10 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Single-Port Ethernet MAC Controller with 8-Bit or 16-Bit Non-PCI Interface |
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