RIID硬件原理和其实现.pptVIP

RFID硬件原理简介 ——以AS3990阅读器芯片为例;涉及的一些基础概念 RFID硬件结构及各部分作用 AS3990阅读器芯片介绍; 基带：指信号的频谱从零频率附近开始。 频带：指信号的频谱具有带通形式且中心频率远离零频。携带有消息；适合在信道中传输。 ;ASK调制和PSK调制;ASK信号波形(OOK);ASK解调;PLL(锁相环);混频（器件的非线性）;RFID中发射机混频结构;GEN2协议;RFID系统工作原理;相互认证通过之后，阅读器会向电子标签发出读、写、锁定、kill、盘存等操作指令。;阅读器发射未调载波信号作用;电磁反向散射;一种反射调制的电路实现;RFID系统工作波形;RFID读写器硬件组成;AS3990/AS3991芯片简介;;Comprise of;Power up and operations;Communication;Transmitting and receiving modes;接口总线(interface bus);parallel 10-pin bus can be configured and used as a serial peripheral interface(SPI) exclusive , can not switch between them in a single application. The parallel mode is selected if all IO pins are low during low to high transition of the EN pin (enable). ;The reader will always behave as the “slave” connected to the host system (MCU), which behaves as the “master” device. The host system initiates all communications. The reader has an IRQ pin to ask for host system attention. ;Communication is initialized by a Start condition, which should be followed by an Address or Command word. The Address and Command words are 8-bits long. Communication is closed by an appropriate stop condition. ;命令/地址格式;Continuous address mode noncontinuous address mode command mode. Continuous address mode needs to be closed by StopCont condition while the other two modes need to be terminated by StopSgl condition. ;Continuous address mode;组合模式;Registers 12, 14, 15, 16, and 17 are three bytes deep. They can be accessed by Continuous address mode only. The least significant byte is accessed first. It is possible to access only deep register in a single communication stream。;The 24 bytes deep FIFO register can be accessed by Continuous address mode only.) It is allowed to use communication stream combined of command mode and address mode. Example: Reset FIFO, Transmit, write to 1D, 1E for transmission length, and continuously to 1F for filling FIFO with transmission data.;Start = start condition Adr = address with Cont bit low Adrc = address with the C