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Domain namePort numberbroker.emqx.io1883Key commandsAT+CMQTTSTARTAT+CMQTTACCQ=0, "client test0"AT+CMQTTWILLTOPIC=0,4AT+CMQTTWILLMSG=0,4,1AT+CMQTTCONNECT=0,"tcp://broker.emqx.io:1883",60,1AT+CMQTTSUB=0,4,1 //Subscribe one topic fr...

RS485自动切换电路：数据收发原理。TX为高电平，三极管导通，RE为低电平使能，RO收数据有效，MAX485为接收态。据1时，TX为高电平时，三极管导通，DE为低电平，此时收发器处于接收状态，驱动器就变成了高阻态，也就是发送端与A\B断开了，此时A\B之间的电压就取决于A\B的上下拉电阻了，A为高电平、B为低电平，也就成为了逻辑1了。 1&&0=1...

If ST-LINK selects automatic reset, but it fails to reset automatically after downloading, it may be that the latest PACK is not installed, and it can be reset automatically after installing the latest PACK.Sometimes the driver is installed, but it ca..