1pcs Pl2303 Module USB To TTL / USB TTL / 9 Upgrade Board / STC Microcontroller Programmer PL2303HX For Arduino|usb to ttl|usb tousb to usb - AliExpress
CH340G USB to RS232 TTL module schematic (D-SUN-V3.0) · Nice Circuits - Electronics, 3d printing and robots
CH340G USB to RS232 TTL module schematic (D-SUN-V3.0) · Nice Circuits - Electronics, 3d printing and robots
Usb to Serial/TTL Adapter : 5 Steps - Instructables