1数字系统发展及基本概念.ppt

* Single Chip Computer/ Micro Controller Unit（MCU） 除开通用CPU所具有的ALU和CU，还有存储器（RAM/ROM）寄存器，时钟，计数器，定时器，串/并口，有的还有A/D，D/A INTEL MCS/48/51/96（98） MOTOROLA HCS05/011 * Analogue to Digital Converter (ADC) Digital to Analogue Converter (DAC) Pulse Width Modulation ( PWM) Output Lines Network Interface Units（SCI、SPI、 I2C 、 CAN、USB、Local / Wide Area Networks (LAN, WAN)） memory and more … JTAG * * 在数字逻辑电路中，理想的逻辑1定义为器件的电源电压，称为“强1”；逻辑0定义为0V，称为“强0”。在实际应用中，由于温度变化、电源电压波动、干扰及元件特性变化等因素的影响，不能如此精确地定义逻辑0和逻辑1，而是定义两个电压范围来分别表示逻辑0和逻辑1。 * 图 1.3.2表示了三个数据采样点转换为8位二进制数字的对应关系，第三个采样点的模拟值接近5V，因此用转换为二进制的数值也比较大，为二进制使用8位二进制数表示模拟信号，只能由0~255共256（28）个整数。因此，这是说明数字信号数值上是不连续的另一含义。显然，使用的ADC二进制位数越多，越可以精确地表示原始的模拟信号，转换误差比较小。 * * * 往届学生都感觉数电内容比较零散。其实是课时的无法介绍一个完整的数字系统。处理器课程实质是数电的综合。 无论IC技术发展多么迅速，数字IC内部都是数字基础——比如，单片机原理、DSP等课程都是学习某个处理器芯片内部结构。 * 作业是检查学生学习情况的重要一环，任何有关课程问题都可以通过作业和我交流。如果Copy，等于放弃自己的机会。 上课人多，禁止喧哗，欢迎举手讨论。 班干部应该多与我沟通，协助维持纪律、 * * Figure shows an example of analog signal processing. The circuit in the illustration filters a signal from a sensor using an operational amplifier and then controls an actuator with the result. Since the ideal filter is impossible to design, the engineer must design the filter for acceptable response, considering variations in temperature, component aging, power-supply variation, and component accuracy. The resulting circuit typically has low noise immunity, requires adjustments, and is difficult to modify. * Processing in this circuit begins with band limiting the input signal with an anti-alias filter, which eliminates out-of-band signals that can be aliased back into the pass band due to the sampling process. The signal is then sampled, digitized with an A/D converter, and sent to the DSP. The DSP output is processed by a D/A converter and is low-pass filtered to remove the effects of digitizing.The particular filter implemented by the DSP is strictly a matter of software. The DSP can implement any filter that can be implemented using analog techniques. Moreover,