emUSB Device is a high speed USB device stack specifically designed for embedded systems. The software is written in ANSI "C" and can run on any platform. emUSB can be used with embOS or any other supported RTOS. A variety of target drivers are already available. Support for new platforms can usually be added for no extra charge. 


  • High speed
  • Optimized to be used with embOS but works with any other supported RTOS.
  • Easy to use
  • Easy to port
  • No custom USB host driver necessary
  • Start / test application supplied
  • Highly efficient, portable, and commented ANSI C source code
  • Hardware abstraction layer allows rapid addition of support for new devices.

emUSB components

Target USB components

emUSB consists of three layers: A driver for hardware access, the emUSB core and at least a USB class driver or the bulk communication component.

The different available hardware drivers, the USB class drivers and the bulk communication component are additional packages, which can be combined and ordered as it fits to the requirements of the project. Normally, emUSB consists of a driver that fits to the used hardware, the emUSB core and at least one of the USB class drivers MSD, CDC, HID, MTP or the unclassified bulk component

Component Description
USB protocol layer
Bulk emUSB bulk component.
MSD emUSB Mass Storage Device class component.
CDC emUSB Communication Device Class component.
HID emUSB Human Interface Device Class component.
MTP emUSB Media Transfer Protocol component.
Core layer
emUSB Core The emUSB core is the intrinsic USB stack.
Hardware layer
Driver USB controller driver.

emUSB Bulk

The emUSB-Bulk stack consists of an embedded side, which is shipped in source code form, and a driver for the PC, which is typically shipped as executable (.sys). (The source code of the PC driver can also be ordered.)

Purpose of emUSB-Bulk

emUSB-Bulk allows developers to quickly and painlessly develop software for an embedded device that communicates with a PC via USB. The communication is like a single, high speed, reliable channel (very similar to a TCP connection). It basically allows the PC to send data to the embedded target, the embedded target to receive these bytes and reply with any number of bytes. The PC is the USB host, the target is the USB client. The USB standard defines 4 types of communication: Control, isochronous, interrupt and bulk. Experience shows, that for most embedded devices bulk mode is the communication mode of choice. It allows usage of the full bandwidth of the USB bus.