外带看门狗电路的NXP MK20下载BOOT的电路方法  

Circuit Method of NXP MK20 Download BOOT with Watchdog Circuit

作　　者：张俊民 Zhang Junmin(Zhuhai FTZ Oplink Communications,Inc.,Zhuhai 519030,China)

机构地区：[1]珠海保税区光联通讯技术有限公司,珠海519030

出　　处：《单片机与嵌入式系统应用》2020年第11期86-87,91,共3页Microcontrollers & Embedded Systems

摘　　要：针对NXP MK20 MCU在产品应用中需要用到看门狗电路,在下载MCU BOOT时,车间需要断开连接MCU到看门狗芯片的电路,下载完成后又连接电路。为方便车间生产,优化设计出了一种电路方便MCU下载BOOT的电路方法,该方法是利用MCU的下载端口JTAG的TCK信号作为下载BOOT时的喂狗信号,解决了在MCU下载BOOT时由于MCU无喂狗信号导致的下载BOOT时看门狗芯片不断给MCU发复位信号,MCU无法下载完整的BOOT的问题。产品通过测试并且大量出货,该方法能够提高生产效率,提升产品质量。Some products use the NNXP MK20 MCU with watchdog circuit.When downloading MCU BOOT,the operator needs to disconnect the circuit from MCU to watchdog chip in workshop,and then connect the circuit after downloading.It's inconvenient and sometimes forget connect the circuit.In order to facilitate the workshop production,a circuit method is designed to facilitate MCU to download BOOT.This method uses TCK signal of JTAG as the dog feeding signal when downloading BOOT.When MCU is downloaded boot,MCU does not have dog feeding signal,which leads to watchdog chip sending reset signal to MCU constantly when downloading BOOT,and MCU cannot be download complete BOOT.Through testing and a large number of products shipped,this method can improve production efficiency,improve product quality.

关 键 词：看门狗电路 JTAG TCK MCU NXP MK20 BOOT 

分 类 号：TP368.1[自动化与计算机技术—计算机系统结构]