基于嵌入式处理器的vlsi芯片的温度自动控制英文翻译大学本科毕业论文.doc

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1、天津职业技术师范大学2015届本科毕业设计Embedded Processor Based Automatic Temperature Control of VLSI ChipsAbstractThis paper presents embedded processor based automatic temperature control of VLSI chips, using temperature sensor LM35 and ARM processor LPC2378. Due to the very high packing density, VLSI chips get hea

2、ted very soon and if not cooled properly, the performance is very much affected. In the present work, the sensor which is kept very near proximity to the IC will sense the temperature and the speed of the fan arranged near to the IC is controlled based on the PWM signal generated by the ARM processo

3、r. A buzzer is also provided with the hardware, to indicate either the failure of the fan or overheating of the IC. The entire process is achieved by developing a suitable embedded C program. Keywords: Temperature sensor, ARM processor, VLSI chips, Brushless DC motor1.IntroductionWith the phenomenal

4、 developments in VLSI technology, the ambitious IC designers are trying to put more transistors in to smaller packages. So, the ICs run at higher speeds and produce large amount of heat which creates the problem of thermal management. For example, nowadays the CPU chips are becoming smaller and smal

5、ler with almost no room for the heat to escape. The total power dissipation levels now reside on the order of 100 W with a peak power density of 400-500 W/Cm2, and are still steadily climbing. As the chip temperature increases its performance is very much degraded by parameters shift, decrease in op

6、erating frequencies and out-of specification of timings. So the high speed chips must be cooled to maintain good performance for the longest possible operating time and over the widest possible range of environmental conditions. The maximum allowable temperature for a high speed chip to meet its par

7、ametric specifications depends on the process and how the chip is designed.Among the various cooling techniques, heat sinks, heat pipes, fans and clock throttling are usually employed. Among these techniques, fans can dramatically reduce the temperature of a high speed chip,but they also generate a

8、great deal of acoustic noise. This noise can be reduced significantly by varying ,the fans speed based on temperature i.e. the fan can turn slowly when the temperature is low and canspeed up as the temperature increases.The other prominent method is clock throttling i.e. reducing the clock speed to

9、reduce power dissipation. But it also reduces the system performance and the systems functionality is lost.So, the objective of the present work is, to design a hardware system consisting of a brushless DC motor fan whose speed is controlled based on the temperature of the chip, sensed by the sensor

10、 LM35.The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large cons

11、tant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require anyexternal calibration or trimming to provide typical accuracies of 14C at room temperature and 34C over a full 55 to +150C temperature range. Low cost is assured by trimming and calibration at the wafer

12、 level. The LM35s low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 A from its supply, it has very low selfheating, le

13、ss than 0.1C in still air. The LM35 is rated to operate over a 55 to +150C temperature range, while the LM35C is rated for a 40 to +110C range (10 with improved accuracy). The LM35 series is available packaged in hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also availab

14、le in the plastic TO-92 transistor package. The LM35D is also available in an 8-lead surface mount small outline package and a plastic TO-220 package. To monitor the voltage at the terminals of the DC motor fan, the PWM signal is generated by the ARM7TDMI processor. This PWM signal is changed in acc

15、ordance to the output of the LM35temperature sensor. So the important component of this entire project is the temperature sensor.2. DescriptionIn ARM processor based automatic temperature control system, the output of the temperature sensor is fed to the on chip ADC and the output of the ADC is give

16、n to the L293D driver IC which in turn is fed to DC motor fan as shown in the block diagram in Fig. 1. A graphic LCD (128x64 pixels) is interfacedto the ARM LPC 2378 processor to display the temperature of the IC and the speed of the fan. A buzzer is also connected to the processor which gives an in

17、dication, in case of the failure of the fan or overheating of the chip beyond some level. The entire circuit diagram is shown in Fig. 2.Fig. 1. Block diagram.Fig. 2. Circuit Diagram.3. Software DescriptionThe present work is implemented using ARM IAR Workbench IDE and the necessary embedded C progra

18、m is developed and dumped into the embedded processor using Flash magic ISP Utility. The ARM IAR Workbench IDE is a very powerful Integrated Development Environment (IDE) that allows you to develop and manage complete embedded application projects. In-System Programming is programming or reprogrammi

19、ng the on-chip flash memory, using the boot-loader software and a serial port. The LPC2387 microcontroller is based on a 16-bit/32-bit ARM7TDMI-S CPU with real-time emulation that combines the microcontroller with 512 kB of embedded high-speed flash memory.A 128-bit wide memory interface and unique

20、accelerator architecture enable 32-bit code execution at the maximum clock rate. For critical performance in interrupt service routines and DSP algorithms, this increases performance up to 30 % over Thumb mode. For critical code size applications, the alternative 16-bit Thumb mode reduces code by mo

21、re than 30 % with minimal performance penalty.The LPC2387 is ideal for multi-purpose serial communication applications. It incorporates a 10/100 Ethernet Media Access Controller (MAC), USB full speed device with 4 kB of endpoint RAM,four UARTs, two CAN channels, an SPI interface, two Synchronous Ser

22、ial Ports (SSP), threeI2C interfaces, and an I2S interface. This blend of serial communications interfaces combined with an on-chip 4 MHz internal oscillator, 64 kB SRAM, 16 kB SRAM for Ethernet, 16 kB SRAM for USB and general purpose use, together with 2 kB battery powered SRAM makes this device ve

23、ry well suited for communication gateways and protocol converters. Various 32-bit timers, an improved 10-bit ADC, 10-bit DAC, one PWM unit, a CAN control unit, and up to 70 fast GPIO lines with up to 12 edge or level sensitive external interrupt pins make this microcontroller particularly suitable f

24、or industrial control and medical systems.The LPC2378 Microcontroller provides on-chip boot-loader software that allows programming of the internal flash memory over the serial channel. Philips provides a utility program for In-System programming called Flash magic Software.4. Results and Conclusion

25、sEmbedded ARM processor based automatic speed control DC motor fan is designed and implemented.To test the validity of the design, the temperature sensor is kept inside a small oven and its temperature is increased beyond the room temperature. Now the fan is operated to run with full speed and the t

26、emperature is found to comeback to normal temperature. This is repeated with various VLSI chips like Pentium processor, FPGA chips etc. Now the temperature sensor is kept very near to the Pentium processor of the computer and it is observed that, as the time lapses the speed of the fan is automatica

27、lly increased and the temperature of the chip is found to be controlled. These results are displayed on LCD panel. Though the present system is working well in the given environment, still it is worthwhile to highlight the following conclusions. Normally, controlling fan speed or clock throttling ba

28、sed on temperature requires that the temperature of the high speed chip should be first measured. This is done by placing a temperature sensor close to the target chip either directly next to it or in some cases, under it or on the heat sink. The temperature measured in this way corresponds to that

29、of the high speed chip, but can be significantly lower and the difference between measured temperature and the actual die temperature increases as the power dissipation increases. So, the temperature of the circuit board or heat sink must be correlated to the die temperature of the high speed chip.

30、Of course a better alternative is possible with a number of high speed chips. Many CPUs, FPGAs and other high speed ICs include a thermal diode which is actually a diode connected bipolar transistor, on the die. Using a remote diode temperature sensor connected to this thermal diode, the temperature

31、 of the high speed ICs die can be measured directly with an excellent accuracy. This not only eliminates the large temperature gradients involved in measuring temperature outside the target ICs package, but it also eliminates the long thermal time constants,from several seconds to minutes, that caus

32、e delays in responding to die temperature changes.There is also a drawback in fan speed control. Normally the fan speed is controlled by adjusting the power supply voltage of the fan. This is done by a low-frequency PWM signal, usually in the range of about 50 Hz, whose duty cycle is varied to adjus

33、t the fans speed. This is inexpensive and also efficient. But the disadvantage of this method is that it makes the fan somewhat nosier because of the pulsed nature of the power supply. The PWM waveforms fast edges cause the fans mechanical structure to move, which is easily audible.In some systems,

34、it is also important to limit the rate of change of the fan speed. This is critical when the system is in close proximity to users. Simply switching a fan on and off or changing speed immediately as temperature changes is acceptable in some environments. But when users are in nearby, the sudden chan

35、ges in fans noise are highly annoying. So to avoid these effects the fans drive signal must be limited to an acceptable level.5. Future Scope of the WorkIn the present work temperature is sensed using the temperature sensor LM35 and the speed of the motor is controlled by varying the width of PWM ge

36、nerated by the processor. But the temperature sensed by the IC LM35 is not very accurate even though we keep the IC very near to the processor orVLSI chip. So, we can use a remote diode temperature sensor connected to the thermal diode which measures the temperature of the high speed ICs directly wi

37、th excellent accuracy. Another important aspect is a variety of remote temperature sensors with up to five sensing channels is available that can detect the die temperature of the high speed chip and transmit temperature data to a microcontroller.Fan speed regulators with multiple channels of fan ta

38、chometer monitoring can provide reliable control of fan RPM or supply voltage based on commands from an external microcontroller. For this simple ICs are provided by MAXIM MAX6660 and MAX6653. The first IC can sense the remote temperature and controls the fan speed based on that temperature. It prod

39、uces a DC supply voltage for the fan through an internal power transistor. The second IC also performs a similar function but drives the fan with a PWM waveform through an external pass transistor. Both include complete thermal fault monitoring with over temperature outputs, which can be used to shu

40、t down the system if the high speed chips get too hot. So, the present work can be improved further by using the above mentioned techniques.基于嵌入式处理器的VLSI芯片的温度自动控制摘要本文介绍了基于嵌入式处理器的VLSI芯片的温度自动控制，同时利用温度传感器LM35和ARM处理器LPC2378来完成设计。由于VLSI芯片密度非常高，同时芯片在工作时很快得到加热，如果不能研制出能是它快速冷却的方法，芯片的性能将会受到很大影响。在目前的工作中，将传感器放置

41、在非常接近接近到IC集成电路的位置来采集芯片的温度，通过由ARM处理器产生的PWM信号来控制集成电路旁风扇的转速。在硬件电路中也提供了一个蜂鸣器，在无法控制风扇或者IC集成电路的过热的情况下都会发出警报。整个过程的实现需要制定一个合适的嵌入式C程序。关键词：温度传感器，ARM处理器，超大规模集成电路芯片，无刷直流电动机1.介绍 随着VLSI超大规模集成电路技术的惊人发展，雄心勃勃的IC设计师正试图将更多的晶体管用更小的体积实现更多的功能。因此，该集成电路运行速度更快，产生更多的热量而造成的新的问题。举例来说，现在世界上的的CPU芯片 变得越来越小，几乎没有空间散热。若消耗100 W的功率的话，

42、峰值功率密度为400-500 W/Cm2，并可能持续上升。随着芯片温度的升高会影响性能的参数变化，从而减少芯片的工作频率和影响时序的规范。因此，在允许的条件范围内，为了让高速芯片能得到最好的工作效率和最长的运行时间，必须要让芯片在短时间内冷却下来。高速芯片所能允许的最高温度，取决于程序的参数规格，以及芯片的设计。 在各种不同的冷却技术中，人们通常使用散热片，热管，风扇以及时钟节流。在这些技术中，风扇可以快速高效的降低高速芯片的温度，但它们也产生大量的噪音。这种噪声可以通过不同的方法来降低，根据风扇转速是由温度来控制，当温度低时，风扇的转速降低；随着温度的提高，风扇的速度会随着提升。另一个有效地

43、的方法是时钟节流，即减少了时钟速度，降低功耗。但它也降低了系统性能和系统运行速度。本工作的目标是，设计一个硬件系统能控制直流无刷电机风扇的转速，芯片的温度则由传感器LM35进行采集.。LM35系列是精密的集成电路温度传感器，其输出电压与采集到的摄氏的温度成线性比。因此，LM35系列比一般的传感器拥有优势，因为我们可以直接通过电压值来确定摄氏温度值。LM35不需要校准或微调，便可以提供提供在室温0.25 精度和-55 +150温度范围。由于LM35系列不需要校准，所以该传感器比较经济，低成本。LM35的低输出阻抗，线性输出和精确的校准的特点使固有接口的读数和控制电路特别容易。它同时可用于单电源输

44、出和多电源输出。由于它只需要60微安的电流供应，所以它自身产生的热量较低，在真空中约升温0.1 。LM35 在-55 +150温度范围内可以正常的工作，而LM35C可工作的温度范围为-40 +110。LM35系列可封装在密封的TO - 46晶体管内，而LM35C，LM35CA和LM35D也可用塑胶TO-92晶体管封装。LM35D也可以用8引脚小型封装和塑料的TO - 220封装。由ARM7TDMI处理器所产生的PWM信号来控制直流风扇电动机两端的电压。PWM信号的变化与LM35温度传感器的电压输出同步。因此，这整个项目的重要组成部分是温度传感器。 2 描述 在ARM处理器为基础的温度自动控制系

45、统，温度传感器输出是由芯ADC来控制。而ADC的输出是与IC相连，IC L293D的驱动信号直接送到直流风扇电机中，系统框图如图1所示。LCD图形液晶显示器（128x64像素）的接口与ARM LPC 2378处理器相连，来显示该集成电路的温度和风扇转速。蜂鸣器同样是连接ARM处理器，在无法控制风扇和芯片过热的情况下会发出警报，整个电路图如图2所示。 图1 系统框图图2电路图3 软件介绍 目前的工作是使用ARM IAR工作台IDE，嵌入式C程序和使用Flash ISP工具处理器进行嵌入式开发。ARM IAR的工作台IDE是一个非常强大的集成开发环境（IDE），允许开发和管理完整的嵌入式应用项目。

46、在系统编程这一环境下我们可以采用引导加载器软件和使用一个串行端口进行编程或重新编程闪存记忆体中的程序。LPC2387单片机是基于16/32位的ARM7TDMI-S CPU的实时仿真，它同时结合了512 kB嵌入式闪存单片机的特点。128位宽度的存储器接口和独特的加速结构使32位代码执行在最大时钟频率下运行。在Thumb模式下，中断服务程序和DSP算法的关键性能能提高30以上。对于重要代码应用，其他16位代码在Thumb模式性能损失可减少超过30。LPC2387是多用途串行通信应用的理想选择。它由一10/100以太网媒体访问控制器（MAC），4个端点的USB全速设备内存，4个UART，两个CAN

47、通道，一个SPI接口，两个同步串行端口（SSP）的，3 个I2C接口，和一个I2S接口组成。这种融合了串行通信接口与频率为4 MHz内部振荡器，64 KB的SRAM记忆体，16个以太网，16 KB的USB ，连同2 KB的电池供电SRAM的功能非常适合于协议转换器的转换。32位定时器，10位DAC，一个PWM单元，一个CAN控制装置，以及多达70个的GPIO线路和12个外部中断引脚使这个单片机特别适合应用在工业控制和医疗系统等。LPC2378单片机提供芯片的引导加载器软件，允许在串行通道的内部快闪记忆体内编程 。飞利浦提供了一个在系统实用程序即所谓闪光魔术软件编程。 4 结果与结论 基于嵌入式

48、ARM处理器的温度控制系统的设计和实施已经完成了。为了验证设计的有效性，温度传感器被放在一个比室内温度高的烤箱内。这时风扇在全速运行并发现温度重返正常温度。我们重复的用各种不同的超大规模集成电路来做这个实验，像奔腾处理器芯片，FPGA芯片等。我们将温度传感器放在接近奔腾处理器的计算机的位置，慢慢的我们观察到风扇的速度自动增加，芯片的温度被控制。这些结果在LCD液晶显示面板上可以看见。虽然目前的系统在特定环境下是行之有效的，但以下结论仍然是值得强调。 一般情况下，使用控制风扇速度或时钟节流的方式来控制温度的条件是必须及时的检测出目标芯片的温度。这个实验中通过放置一个温度传感器在目标芯片旁边，在某些情况下，也可以放在被测物体下方或者是散热器下。以这种方式检测高速芯片的温度与实际温度较为接近，但也有可能测量温度比管芯温度上升时温度要低。因此，电路板或散热片温度和高速芯片管芯的温度必须相关。当然如果有很多高速芯片是更好的选择。许多CPU，FPGA和其他高速集成电路包含一个热二极管，其实是一个连接双极晶体管的二极管。使用远程二极管温度传感器连接到这个热二极管，得出的结果可以与直接测量VLSI芯片一样精确。这不仅消除了目标IC的封装与室外温度有较大的温差所产生的误差，它也消除了芯片从几秒钟到几分钟内由于温度变化作出反应的延误。