pert:
SandroMesquita's module:
If you already own that module, it will work fine. However, I strongly recommend against buying this particular module because it's very inferior to other modules that are similarly priced. The biggest problem with this module is that it does not have the DTR pin broken out. The DTR pin is used to automatically reset Arduino boards at just the right time during the upload. When you don't have a DTR pin, you will need to manually reset the board at the correct time. To know the correct time, watch the black console window at the bottom of the Arduino IDE window until you see something like this appear:
Sketch uses 4246 bytes (13%) of program storage space. Maximum is 30720 bytes.
Global variables use 204 bytes (9%) of dynamic memory, leaving 1844 bytes for local variables. Maximum is 2048 bytes.
As soon as you see that, press and release the reset button. I recommend only buying USB to TTL serial modules that use the standard "FTDI header" pinout: - DTR or RTS - RX - TX - VCC - CTS - GND That will allow you to plug the adapter right in to an Arduino Pro Mini, or many other boards that use this standard pinout. If you get an adapter with a non-standard pinout, you would need to use a mess of jumper wires to adapt it to the standard pinout. They don't need to have an FTDI chip, CH340, PL2303, CP2102, etc. will work too. This is the module I use: https://www.ebay.com/itm/312519249465  The Chinese sell them on eBay for $0.74 USD w/ free shipping. The FT232 chips on them are counterfeit, but they work just fine.
Very good your comments. Thankyou.