Introduction: USB to TTL UART Converter

About: I'm a mechanical engineer, and I like computer programming, mechanics, electronics and specially the robotics.

In many microcontroller-based projects, you may need to communicate with PC. There are several ways to do this like RS232 COM port, USB port, parallel port, WIFI, Bluetooth, etc. You cannot directly connect computer to your microprocessor, you need wireless modules for WIFI and Bluetooth, voltage convertors for RS232 and parallel port and a protocol engine for USB. Here I am going to show you how to make a simple USB convertor for your projects. If you are interested in making one yourself follow me.

Step 1: Things You Need

  • 1x Type A male USB connector
  • 1x 3.5mm stereo audio male connector
  • 1x FT232RL IC
  • 1x 4.7uF electrolyte capacitor
  • 1x 10nF ceramic capacitor
  • 2x 100nF ceramic capacitors
  • 1x Ferrite bead
  • About 1-5 meters 4-wire cable
  • Copper board
  • An empty case of dental floss (or anything can be used as a box)
  • PCB making tools (sandpaper, glossy paper, laser printer, PCB file, iron, ferric chloride etchant)
  • Soldering tools (iron, wire and oil)
  • FT232R USB driver (

Step 2: Making PCB

Print the PCB file (you can find it at previous step) with a laser printer on a glossy paper without scaling. Cut some copper board, clear it with sandpaper, put printed papers on it and press hot iron on them about 10 seconds. Wait for the board to became cool and remove the papers, if there are parts that circuit does not reflected well fix them with a CD marker. Then soak board in ferric chloride etchant and wait till no copper parts can be seen. Wash the board with water, dry it and clear it with sandpaper. Use a small drill to fine the edges of copper on the board and drill the holes.

Step 3: Soldering FT232RL

Fasten a narrow wire to the tip of soldering iron (you can use electronic components legs). Put some solder on PCB where the FT232RL IC should be placed. Put the IC on its place carefully hold it among your fingers and put soldering iron on its legs one by one. Notice the direction of IC (the dot should be one the opposite side of USB).

Step 4: Soldering Other Components

Solder other components according to the text on the board. Notice the direction of 4.7uF electrolyte capacitor. Cut about 20cm from the cable solder it to USB side and solder the rest of the cable to the UART side.

Step 5: End Connectors

Solder other end of cables to the USB and 3.5mm audio connectors according to the diagram. You can also use your own arrangement for 3.5mm audio connector.

Step 6: Case

Drill to holes on empty dental floss case, put the board in it, glue cables and close it.

Step 7: Final Step

Download USB COM Port driver from install it on your PC and use the convertor you made yourself. I uploaded the windows driver for you here.

I also made an adapter for RS232 COM port you can find here.