ZYAMY A61 CP2102 Module USB to TTL USB 2.0 Serial Module UART STC Downloader with 5 Pin Dupont Cable

Tips ( very important ):
TXD: the sender, usually expressed as its sender , the normal communication must be connected to another device RXD.
RXD: the receive side, generally expressed as the receiving end of their normal communication to another device connected to TXD.
When normal communication TXD never received their equipment RXD!
Collected spontaneously : normal communication other devices connected RXD TXD, so if you want to receive data sent their name suggests, it is their own transmitted data received , which is connected directly to its own TXD RXD, used to send and receive the test itself is normal, is the quickest and easiest way to test if a problem occurs first do the test to determine whether a product failure. Also known as the loopback test.

Level logic:
TTL level: typically binary data representation , provides +5 V equivalent to the logic "1", 0V is equivalent to logic "0" , is called a TTL signal system is the positive logic
RS232 level: the -12V to -3V, equivalent to logic "0", +3 V to +12 V logic level is equivalent to logic "1" , the negative logic.

Feature:
1 The main chip CP2102, generate a virtual serial port after installing the driver
2 USB to take power, leads to the interface includes 3.3V(