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XTAL Design

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Preliminary Review102109p4Conexant2-334/25/03Preliminary Information/Conexant Proprietary and Confidential

CX2415X Interactive TV Development Platform Application NoteCX2415X Applications Information2.6 CX2415X Crystal InterfaceThe CX2415X can be utilized with a variety of crystals and crystal oscillators. Fundamental or third overtone crystals can be attached directly to the CX2415X. Alternatively a fundamental 10.111MHz or 12.238MHz crystal can be attached to the CX24109 and a clock from the CX24109 can drive the CX2415X crystal input pin.

The specific crystal frequencies to be used with the CX2415X will not be specified until revision B silicon has been received and evaluated. Several frequency choices will be evaluated including: 10.111MHz, 12.238MHz, 16.317Mhz, 40.444MHz, and 48.952MHz.

Systems not utilizing the internal channel 3/4 modulator should use a 10.111MHz crystal, either attached directly to the CX2415X, or attached to the CX24109 device in systems so equipped. Systems utilizing the internal channel 3/4 modulator will end up using one of the five crystal frequencies listed above, the specific frequency to be determined by Conexant Systems, Inc., following revision B CX2415X silicon validation.

A 10.111MHz fundamental mode crystal attached to the CX24109, with the CX24109 supplying the clock signal to operate the CX2415X provides the lowest overall system cost. But for systems utilizing the internal RF modulator, Signal/Noise performance requirements may dictate that the crystal be attached directly to the CX2415X device, resulting in a need for two crystals in systems using the CX24109. This requirement will be clarified following revision B CX2415X silicon validation.

2.6.1 Crystal CircuitsFundamental crystals generally provide better performance than 3rd overtone crystals, and they eliminate the problems associated with the tank circuit which is required when using 3rd overtone crystals. If a third overtone crystal is placed in a circuit like Figure2-21, the circuit will have a undesirable tendency to oscillate at the crystal’s fundamental mode, since the circuit naturally has higher gain at the fundamental. Therefore, a tank circuit like that used in Figure2-22 is used to suppress oscillation at the fundamental frequency. The tank circuit used to suppress the fundamental generally loads the oscillator slightly, and impairs the gain, startup and final envelope amplitude. The crystals used in the CX2415X should be specified based on a 10pF standard load capacitance, and should have at least 50ppm tolerance in NTSC applications, and 25ppm or better tolerance for PAL/SECAM applications. Figure2-21 and Figure2-22 illustrate the crystal circuits for fundamental and third overtone respectively.

When driving the crystal oscillator with external clock circuit, it is necessary to use some external components to make sure the DC operating point in the oscillator is preserved. Figure2-23 illustrates the circuit for using the CX2415X with external drive signal such as an external crystal oscillator.Prel

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minary Review

2-34Conexant102109p4Preliminary Information/Conexant Proprietary and Confidential4/25/03

CX2415X Applications InformationCX2415X Interactive TV Development Platform Application NoteFigure2-21.Fundamental Mode Crystal Circuit

Figure2-22.3rd Overtone Crystal Circuit102109_017FundamentalMode Crystal

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102109_018Third OvertoneCrystal

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102109p4Conexant2-354/25/03Preliminary Information/Conexant Proprietary and Confidential

CX2415X Interactive TV Development Platform Application NoteCX2415X Applications InformationFigure2-23.Crystal Oscillator Circuit

2.6.2Fundamental Mode Suppression Tank CircuitThe tank circuit used to suppress operation at the fundamental should of course be series resonant at the fundamental with realistic component values. For example, if you choose the inductor to be L=2.7uH, then a realistic capacitance value of about 47pF can be obtained using the series resonant formula to suppress fundamental operation for a 40.444Mhz crystal.

2.6.3Quartz Crystal Model Parameters and how to Measure ThemThe quartz crystal should be modeled with a standard R-L-C, parallel C branch as shown in Figure2-24. The crystal parameters are described in Table2-4.

Table 2-4. Quartz Crystal Model ParametersParameterDescriptionLmMotional InductanceCm (Sometimes called C1 in the industry)Motional CapacitanceRsSeries Resistance (ESR)CoParallel Capacitance of the Crystal

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QN8027_hw AppNote_V_0_24_090831

QN8027_hw AppNote_V_0_24_090831

Contents1Feature Overview (4)1.1Main Feature for QN8027 (4)2Hardware Design (5)REVISION HISTORYwarranties, either express or implied, with regard to this manual and any information contained herein, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. Quintic shall not be liable for errors or for incidental or consequential damages in connection with the furnishing, use, or performance of this document or of any information contained herein. Should Quintic and the user have a separate written agreement with warranty terms covering the material in this document that conflict with these terms, the warranty terms in the separate agreement shall control.1 Feature OverviewThe QN8027 is a high performance, low power, single-chip stereo FM transmitter, designed for MP3 players, GPS. The QN8027 also supports RDS/RBDS data transmit.1.1 Main Feature for QN80272 Hardware DesignThe schematic of the reference design please see the next chapter.2.1 Power SupplyQN8027 integrated LDO inside, and the VCC accept the power supply voltage range from 2.7V~5.0V.2.2Figure 1. I2C Write and Read Operation Timing2.3 Clock InterfacePin 1’XTAL2’ and pin 2 ‘XTAL1’ is used for crystal input. QN8027 accept 12MHz and 24MHz crystal. And the crystal need 20pF load cap. The chip default setting is 24MHz crystal. If the crystal changed, it need do some registers change and do recalibration to make chip suit for crystal setting.Figure 2. Crystal Input InterfaceQN8027 accept external clock input. It accept square clock with the voltage range 0~UVIO and sin wave single-end and sin wave differential clock input. For sin wave single-end clock input, the voltage of the clock should be large than 350mVpeak. With differential sin wave clock input, the clock inputFigure 4. Sin Wave Clock Input Interface2.4 Audio Input InterfaceQN8027 have integrated VGA inside of chip and can change the input impedance to 5k ohm, 10k ohm, 20k ohm and 40k ohm by register control.With default register setting, audio input only accepts maximum 1000mVp-p voltage. And audio input needs a capacitor to separate DC voltage. The suggested capacitor value is 4.7uF.2.5 Differential Audio Input Reference CircuitIn order to further improve common mode noise restrain and build up a low pass filter at the front end of audio input, we supply a reference design for differential audio input circuit.2.6 FM Transmitter Antenna InterfaceQN8027 use auto turn for every channel with the integrated adjustable capacitor and can make the PA output voltage get maximum at every channel.The PA structure of QN8027 needs an inductor at the outside of the chip, which used to make a resonant2.7 Difference between Qn8000 and QN8027QN8000 only accept 7.6MHz crystal; QN8027 accept 12MHz/24MHz crystal.QN8000 use 2 wire and 3wire control interface; QN8027 use only I2C control interface. QN8000 and QN8027 have different device ID.2.8Figure 9. External PA Reference Circuit for 75cm antenna2.9 Schematic of QN8027 Reference Design2.10 PCB Layout for QN8027 The example layout as show in the following:Under the chip and the RF signal trace, there need an integrative GND copper. This copper will help to2.11 AN Example of PCB LayoutQuintic Corporation (USA) 3211 Scott Blvd., Suite 203 Santa Clara, CA 95054Tel: +1.408.970.8808Fax: +1.408.970.8829Email: support@ Web: Quintic Microelectronics (China) Building 8 B-301A Tsinghai Science Park 1st East Zhongguancun Rd, Haidian Beijing, China 100084Tel: +86 (10) 8215-1997Fax: +86 (10) 8215-1570Web: Quintic Microelectronics and Quintic are trademarks of Quintic Corporation. All Rights Reserved.。

Sigmatel STMP3710方案MP3电路原理图

Sigmatel STMP3710方案MP3电路原理图


PREV
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VOL+
VOL-
LCD_CS LCD_RS LCD_RESET LCD_WR LCD_BUSY LCD_RD PWM0 PWM1 PWM2 PWM3 PWM4
28 41 42 43 27 44 91 87 83 84 82
LCD_CS LCD_RS LCD_RESET LCD_WR LCD_RD VDDIO_P
"Menu" & USB Recovery Mode
SW2 R3 1K PSWITCH SW PUSHBUTTON R4 100K 10%
VDDXTAL
GND 73 68 67 VDDXTAL REFP VAG
C
VDDXTAL
"Power/Play/ Pause Button"
C29 0.1uF
C30 0.1uF GND
Y2 32.768kHz 30ppm C36 XpF C37 XpF
RTC_XTALI RTC_XTALO
I2C_SDA I2C_SCL ROTARYB ROTARYA
80 81 25 24
R18 R19
0/NC 0/NC
I2C_SDA I2C_SCL
D18 LED
D17 LED
D10 LED
D12 LED
The 24 MHz crystal should be located close to the STMP37XX. Consult crystal manufacturer datasheet for recommended load capacitor values (typically 10-18pF). Cload = [ (C26*C27) / (C26+C27) ] + Cstray where Cstray = stray PCB capacitance, typically 4 - 6 pF Note: For Microsoft DRM applications use a 30 ppm crystal. NOTE: The crystal load capacitors C26 and C27, should be resized appropriately when STFM1000 is connected to the crystal circuit. Note that STFM1000 TB2 has 1-2 pF of internal capacitance.
Arduino MEGA2560原理图

Arduino MEGA2560原理图

6 1 3 5 IN ON/OFF GND NC/FB 4 OUT 5
CMP IC7B
7
2
GATE_CMD
C13+3V3
Reference Designs ARE PROVIDED "AS IS" AND "WITH ALL FAULTS. Arduino DISCLAIMS ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, REGARDING PRODUCTS, INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE Arduino may make changes to specifications and product descriptions at any time, without notice. The Customer must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Arduino reserves these for future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them. The product information on the Web Site or Materials is subject to change without notice. Do not finalize a design with this information.
自行车测速系统设计

自行车测速系统设计

2.2单片机
2.2.1单片机介绍
单片机是一种集成在电路芯片，是在一块硅片上集成了中央处理器（CPU）、只读存储器（ROM）、随机存储器（RAM）以及定时器/计数器，各种输入/输出(I/O)接口。由于这样的一块芯片具有一台计算机的功能，因而也被称为单片微型计算机。系统所使用的是51系列单片机，它可以把可开发资源全部提供给使用者。
STC89C54RD+单片机为40 脚双列直插封装的8 位通用微处理器。片内程序存储器内含16KB的Flash程序存储器。片内数据存储器内含1280字节的RAM。具有3个可编程定时器，具有32根可编程I/O口线。 中断系统是具有8个中断源、4个级优先权的中断结构。
STC89C54RD+按其引脚功能分为四部分,即主电源引脚VCC和VSS、外接晶体引脚XTAL1和XTAL2、输入/输出（I/O）引脚P0、P1、P2、P3（共32根）、控制或与其它电源复用引脚RST、ALE、PSEN和EA/VPP。
国内外现在已经有生产销售类似的自行车测速仪里程表，有些简单的产品功能比较单一，就是单单只有测速或里程的功能，然而一些复杂的产品除了测速和里程功能外，还集成了GPS全球定位、单次行车里程、平均速度、时钟、行车时间、车轮转数。未来的发展趋势可能还将加入MP3和短信收发、新闻播报、通讯功能等，使得自行车测速仪更加的人性化、现代化、生活化。相信未来的测速仪会受到更多人的青睐，也将成为人类社会生活中的必需品。
关键词：里程/速度，时间，温度，霍尔元件，单片机，LCD
Abstract
This designmainly expounds thedesign of ameasuringinstrument based on single chip ing single chip as the core,the use ofthe Holzer sensor,DS18B20 temperature sensor\/DS1302 clock chip,realize the measurement of thebicycle mileage,speed,temperature,time and other parameters,and caneasily bespeed andmileagefor real-timedisplayof liquid crystal display,andwhenpower is offcan save themileage information.Design ofvelocimeteris mainly composed ofdesign and program designof the hardware circuitsof two parts.The design of hardwareis mainlycollectedthe number of pulsesper secondinto single chip microcomputer systemusing the Holzersensor,then bycomputingSCM systemand processing resultto theLCDdisplay.The software designuses the modularstructure,make thelogicprogram moresuccinct.Thehardware to coordinate the operationunder the software control.The simulation and experimental results show,the design of hardware circuit andsoftware programis correct,the actual hardware circuitcanmeet the design requirements.