DIY Electronics

USB-Serial converter module

This article introduces a prototype of an USB-Serial module, which BeatCraft, Inc. has created. This prototype is capable of providing a connection between USB and RS-232C (9-pin) Serial devices. Its converter chip is FTDI Ltd.'s FT232. As Windows 7 initially supports this chip, its driver is automatically installed as the USB cable is connected to a Windows PC. To use with Windows XP and other OSes, a specific driver is required for its targeted OS, and the drivers are available at the support page of FTDI Ltd.


  • The example of how the device manager of Window 7 recognizes this converter module (in Japanese).


COM Port number highly vary and is depending on user's working environment. In this example, COM port is recognized as “COM18”.

This USB-Serial converter module can be used for not only an USB-serial (USB and RS-232) converter, but also a converter for TTL level (3.3V and 1.8V) serial communication.

How to Use the converter module

For a case that RS232-C terminal is connected to a serial communication device

  • At J1, the jumper pin are placed at either between 13 and 14 or between 15 and 16.
  • An USB cable is connected to USB connector (miniB) at P1, and the other end of the cable is attached to a PC. As power is provided through the USB cable, the LED at L1 is turned on.
  • At P2 is RS-232C (9-pin) is attached to a Serial communication device.

For a case that connect to a TTL level serial communication device

  • At P1, the USB connector (MiniB) is connected to a USB cable. At the other end, the same USB cable is attached to a PC. As power is provided from the USB cable, the LED at L1 is turned on.
  • At J1, the needed lines are connected. On the other hand, the lines, which do not need to use, remains open.
  • At J1,the jumper pin is placed at either between 13 and 14 or between 15 and 16. The location of placing the pin is depending on the voltage you apply.

At J1 terminal, from pin#1 to pin#9, these pins are used for TTL level serial communication, which can be used for connecting to a one-board microcomputer. From pin#13 to pin#16, these pins are reserved for setting jumper pins, which are used for the selection of voltage level. pin#11 and pin#12 remain void.

From pin#1 to pin#9, the allocation of these pins is identical to RS-232C (EIA-574) of 9-pin. The voltage level of serial signal are should be the same as targeted device such as one-board microcomputer. To use Jumper pins, the voltage level can be selected at either 3.3V or 1.8V. (Therefore, this converter cannot be connected with Arduino and other devices, which require 5V line.) For the selection of voltage level, if a jumper is put between 13 and 14, the voltage will be at 3.3V or if it is placed between 15 and 16, it will be at 1.8V.

Pin Allocation of J1

133.3V Out Put
14IO Power Supply
151.8V out put
16IO power Supply

Revision History

  • 2012/3/05 The article is initially uploaded.

Attach file: fileusb-serial.jpg 1497 download [Information] fileusb-serial.png 1416 download [Information] fileBC10-105-0001.pdf 1253 download [Information]

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Last-modified: 2012-03-05 (Mon) 03:31:16 (3334d)