Master & Slave

USB I2C Adapter MS

  • Plug & Play
  • No additional driver required
  • HID device drivers are included in common operating systems
  • Open interface description enables communication without a DLL
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The USB I2C Adapter MS is a universally applicable USB to I2C converter. The converter offers system designer a quick easy way to add USB functionality to any I2C-Circuits. Implementing this converter into a system can completely offload USB connectivity and processing standard protocols from the system, thereby significantly reducing the software development. System designer just need to connect it to an existing I2C-Bus. The converter may operate as master or as slave. Switching between Master Mode and Slave Mode is done via software.


With the USB I2C Adapter MS as Master numerous bus participants can be addressed purposefully via USB such as IO-Expander, sensors, LCDs, 7 segment display, stepping motors AD/DA converters, real time clocks, tone generators, RAM EEPROM, etc. The SCL-frequency is adjustable by software from 500Hz up to 400kHz. The duty cycle SCL-High/ SCL-low can be also individually adjusted. The converter as master has an interrupt input. Thus it is possible to react to external events e.g. when using IO-Expander like the PCF8574. This interrupt input can be activated (rising o. falling edge) or deactivated by software.


In order to send data to PC (in Slave Mode), a I2C master addresses this converter as slave and writes the data on the I2C bus. This is the simplest way to communicate with PC using USB. The converter has an interrupt output. Thus it is possible to inform a I2C Master that data, which was received from PC, is ready to read. The adapter’s slave address may be changed any time by the software. General Call (0x00) is also available.


The adapter contains an I2C level shifter on board. Thus, it is possible to connect the adapter to an I2C bus having different voltage levels between 2.5V and 15V.


An 8KByte EEPROM is on board. Therefrom 256 Bytes are reserved for internal use by the board. The remaining memory is available to the user.


The adapter does not need any additional drivers. The most of the operating systems offer such drivers (e.g. Windows, Linux, Mac, etc..). The adapter uses the standard HID driver offered by Windows (WIN98SE, ME, 2000, XP, Vista, Win7, Win8). It is just plug & play. A 32bit DLL (for Windows) is also included in delivery. This makes the integration of the adapter into own applications possible. A detailed description and some examples about the DLL are also included. e.g. you as developer could immediately begin with the actual work without dealing with troublesome drivers. If you do not want to use our DLL, so it is also possible to communicate with the adapter using the Windows API function WriteFile() and ReadFile(). Other operating systems should also offer similar function.


No separate power adapters for voltage supply are needed. 3,3V and 5V outputs are available. The total current consumed the adapter and the target system must be limited to 100mA by the user when using these power outputs. Thus e.g. an EEPROM Programmer or a temperatue measuring station can be realized.


Some of the software Tools are for the developer very helpfully. Thus it is possible to test immediately I2C devices. The software “IIC Control” supports EEPROMS of 1kbit (128 bytes) to 1Mbit (128k byte).


Part number: #010502
Price: 117,- EUR plus VAT & shipping



  • Bus-powered
  • USB 1.1 and 2.0 compliant / Full Speed
  • Configurable I2C frequency via software between 500Hz – 400kHz
  • adjustable duty cycle (SCL-frequency)
  • On board I2C level shifter, I2C levels from 2.5V to 15V
  • supports multi-master
  • Master transmit & receive
  • Slave transmit & receive
  • supports clock streching
  • 7bit addressing
  • Interrupt input for external events
  • no additional drivers needed for Windows (and others)
  • 54*35 mm²


Included in delivery:

  • USB I2C Adapter MS(Master & Slave)
  • IIC Device Control
  • 32bit DLL for Windows
  • Examples for Delphi, VB, VC++ and C++ Builder
  • DLL Manual
  • Interface manual for accessing the adapter without DLL


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Data sheet & manual of the USB I2C Adapter


Manual of the Dynamic Link Library (DLL)


Description of the software interface for communication over HID


Delphi example shows the implemention of the DLL


Delphi example uses windows native API functions to communicate with the adapter (without DLL)


Delphi example uses the xDev DLL to communicate with multiple devices.


C ++ Builder example for communicating with the adapter using DLL


VC exAmple for communicating with the adapter using DLL


VB example for communicating with the adapter using DLL