The PCA9555 is a 24-pin CMOS device that provides 16 bits of General Purpose parallelInput/Output (GPIO) expansion for I2C-bus/SMBus applications and was developed toenhance the NXP Semiconductors family of I2C-bus I/O expanders. The improvementsinclude higher drive capability, 5 V I/O tolerance, lower supply current, individual I/Oconfiguration, and smaller packaging. I/O expanders provide a simple solution whenadditional I/O is needed for ACPI power switches, sensors, push buttons, LEDs, fans, etc.The PCA9555 consists of two 8-bit Configuration (Input or Output selection); Input, Outputand Polarity Inversion (active HIGH or active LOW operation) registers. The systemmaster can enable the I/Os as either inputs or outputs by writing to the I/O configurationbits. The data for each Input or Output is kept in the corresponding Input or Outputregister. The polarity of the read register can be inverted with the Polarity Inversionregister. All registers can be read by the system master. Although pin-to-pin and I2C-busaddress compatible with the PCF8575, software changes are required due to theenhancements, and are discussed in Application Note AN469.
上传时间： 2013-11-13
上传用户：fredguo
The PCA9548A is an octal bidirectional translating switch controlled via the I2C-bus. TheSCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individualSCx/SDx channel or combination of channels can be selected, determined by thecontents of the programmable control register.An active LOW reset input allows the PCA9548A to recover from a situation where one ofthe downstream I2C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets theI2C-bus state machine and causes all the channels to be deselected as does the internalPower-on reset function.
上传时间： 2013-10-13
上传用户：bakdesec
The PCA9557 is a silicon CMOS circuit which provides parallel input/output expansion for SMBus and I2C-bus applications. The PCA9557 consists of an 8-bit input port register, 8-bit output port register, and an I2C-bus/SMBus interface. It has low current consumption and a high-impedance open-drain output pin, IO0. The system master can enable the PCA9557’s I/O as either input or output by writing to the configuration register. The system master can also invert the PCA9557 inputs by writing to the active HIGH polarity inversion register. Finally, the system master can reset the PCA9557 in the event of a time-out by asserting a LOW in the reset input. The power-on reset puts the registers in their default state and initializes the I2C-bus/SMBus state machine. The RESET pin causes the same reset/initialization to occur without de-powering the part.
上传时间： 2014-01-18
上传用户：bs2005
Although Stellaris microcontrollers have generous internal SRAM capabilities, certain applicationsmay have data storage requirements that exceed the 8 KB limit of the Stellaris LM3S8xx seriesdevices. Since microcontrollers do not have an external parallel data-bus, serial memory optionsmust be considered. Until recently, the ubiquitous serial EEPROM/flash device was the only serialmemory solution. The major limitations of EEPROM and flash technology are slow write speed, slowerase times, and limited write/erase endurance.Recently, serial SRAM devices have become available as a solution for high-speed dataapplications. The N256S08xxHDA series of devices, from AMI Semiconductor, offer 32 K x 8 bits oflow-power data storage, a fast Serial Peripheral Interface (SPI) serial bus, and unlimited write cycles.The parts are available in 8-pin SOIC and compact TSSOP packages.
上传时间： 2013-10-14
上传用户：cxl274287265
基于单片机的步进电机开环控制系统:通过ATMEL89C51单片机对步进电机进行控制,主要介绍了步进电机控制器、驱动电路和LED显示电路的设计,实现了步进电机的开环控制。在步进电机控制器的设计中,重点阐述了脉冲产生电路以及对速度的控制。该系统具有成本低、控制方便的特点。关键词: 单片机; 步进电机; 开环控制 Abstract: The design using ATMEL89C51 single chip to control the step2motor with its controller, driving circuit and LED disp lay circuit to realize step motor open2loop controlwere introduced. For the controller in this design,the circuit to p roduce pulse and the speed controlwere expatiated emphatically. This system possesses features of lower cost, easier control.Key words: single ch ip; step2motor; open2loop con trol
上传时间： 2013-10-13
上传用户：cicizoe
这一颗，我们学习如何让跑马灯自动按照我们预定的顺序进行。这种控制在工控场合经常用到。这个程序里，我们预先定义了一个变化的顺序speedcode，每跑一圈灯就根据预定设置的表格数据来决定下一圈的跑马速度。这样我们就实现了按照预定的顺序自动变化运行。请看代码：-----------------------------------#define uchar unsigned char //定义一下方便使用#define uint unsigned int#define ulong unsigned long#include <reg52.h> //包括一个52 标准内核的头文件sbit P10 = P1^0; //头文件中没有定义的IO 就要自己来定义了sbit P11 = P1^1;sbit P12 = P1^2;sbit P13 = P1^3;bit ldelay=0; //长定时溢出标记,预置是0uchar speed=10; //设置一个变量保存跑马灯的移动速度uchar code speedcode[10]={3,1,5,12,3,20,2,10,1,4}; //10 个预定义的速度char code dx516[3] _at_ 0x003b;//这是为了仿真设置的//可编程自动控制跑马灯void main(void) // 主程序{uchar code ledp[4]={0xfe,0xfd,0xfb,0xf7};//预定的写入P1 的值uchar ledi; //用来指示显示顺序uchar i;RCAP2H =0x10; //赋T2 的预置值0x1000，溢出30 次就是1 秒钟RCAP2L =0x00;TR2=1; //启动定时器ET2=1; //打开定时器2 中断EA=1; //打开总中断
上传时间： 2013-11-20
上传用户：ming529
摘要：本水位监测报警器使用5V低压直流电源（也可以用3节5号电池代替）就可以对5~15厘米的水位进行监测，用LED显示和数码管显示水位，并可以对不再此范围内的水位发出报警。主要采用CD4066、74LS86、74LS32、CD4511芯片，再加上数码管、蜂鸣器、发光二极管、电阻这些器件组成一个简单而灵敏的监测报警电路，操作简单，接通电源即可工作。因为大部分电路采用数字电路，所以本水位监测报警器还具有耗能低、准确性高的特点。关键字：译码电路 报警电路 监测电路 Abstract: The water level alarm monitoring the use of 5 V low-voltage DC power (can also use three batteries replaced on the 5th) will be able to 5 to 15 centimeters of water level monitoring, with LED display and digital display of water level, and this can no longer Within the scope of a water level alarm. Mainly CD4066, 74LS86, 74LS32, CD4511 chips, coupled with digital control, buzzer, light-emitting diode, the resistance of these devices composed of a simple and sensitive monitoring alarm circuits. Because the majority of circuits using digital circuitry, so the water level monitored alarm system also has low energy consumption, high accuracy of the characteristics. Keyword: Decoding circuit alarm circuit monitoring circuit
上传时间： 2013-11-05
上传用户：王庆才
基于PIC单片机的低功耗读卡器硬件设计:本文提出了一个完整的基于串口的智能读卡器子系统设计方案并将其实现。读卡器的设计突出了小型化的要求，全部器件使用贴片封装。为了减小读卡器的体积，设计中还使用了串口窃电的技术，使用串口信号线直接给读卡器供电。为此，读卡器使用了省电的设计，采用了省电的集成电路，并大胆简化了许多传统的设计电路。关键字： 读卡器， 单片机， 串口窃电 Abstract： This paper aims to put forward a complete design of Smart IC card reader based onSerial Port and propose the way of realizing it for the purpose of Network Security. SMD isadopted to make Smart IC reader smaller in this design. To reduce the volume of Smart ICreader， Serial Port powered technology is employed to get power from the signal line of Serial Port. For this reason， low-power consumption components are adopted in the design and some traditional designs are simplified to reduce the power consumption.Keywords： Card Reader； Single-chip Computer； Serial Port Powered IC 卡系统保存了加密算法所需要的工作密钥，供加密算法对网络上传输的数据加密使用，是整个系统网络安全的核心。在IC 卡子系统中，读卡器是一个重要的部分。它起着管理IC卡、在IC 卡和PC或网络计算机间传递数据的重要作用。本文以一片PIC单片机为核心完成了基于RS232 串口的读卡器的硬件设计。
上传时间： 2014-04-14
上传用户：wanghui2438
基于单片机控制的二氧化碳浓度测试计:基于CDM4161二氧化碳气体浓度测试模块以及ATtiny26单片机,提出了一种二氧化碳浓度测试计的设计方案。该方案具有硬件电路简单、成本低、可靠性高、测量准确等优点，具有较高的实用价值。 Abstract: Abstract：A desigh scheme of CO2 concentration meter based on CDM4161carbon dioxide concentration test module and ATtiny26micro-controller is presented in this paper.The design scheme features simple hardware circuit,low-cost,high reli-ability，accurate measurement and it has a high practical value.
上传时间： 2013-11-14
上传用户：zjwangyichao
The C500 microcontroller family usually provides only one on-chip synchronous serialchannel (SSC). If a second SSC is required, an emulation of the missing interface mayhelp to avoid an external hardware solution with additional electronic components.The solution presented in this paper and in the attached source files emulates the mostimportant SSC functions by using optimized SW routines with a performance up to 25KBaud in Slave Mode with half duplex transmission and an overhead less than 60% atSAB C513 with 12 MHz. Due to the implementation in C this performance is not the limitof the chip. A pure implementation in assembler will result in a strong reduction of theCPU load and therefore increase the maximum speed of the interface. In addition,microcontrollers like the SAB C505 will speed up the interface by a factor of two becauseof an optimized architecture compared with the SAB C513.Moreover, this solution lays stress on using as few on-chip hardware resources aspossible. A more excessive consumption of those resources will result in a highermaximum speed of the emulated interface.Due to the restricted performance of an 8 bit microcontroller a pin compatible solution isprovided only; the internal register based programming interface is replaced by a set ofsubroutine calls.The attached source files also contain a test shell, which demonstrates how to exchangeinformation between an on-chip HW-SSC and the emulated SW-SSC via 5 external wiresin different operation modes. It is based on the SAB C513 (Siemens 8 bit microcontroller).A table with load measurements is presented to give an indication for the fraction of CPUperformance required by software for emulating the SSC.
标签： synchronous Emulating serial
上传时间： 2014-01-31
上传用户：z1191176801
