Micro Digital Inc

smxUSBH (Host Stack) and smxUSBD (Device Stack)

Compatible Operating Systems: Optimal support with SMX® RTOS. Easily ported to proprietary environments and other RTOSs, and can be used stand-alone.

Supported Architectures: Host and device support for USB 1.1, USB 2.0 and OTG compliant.

smxUSBH (Host Stack), smxUSBD (Device Stack), and smxUSBO (on The Go) are robust solutions for adding USB connectivity to embedded devices. Written in ANSI-C, the clean, modular design makes USB implementation
surprisingly easy. Developed explicitly for use in embedded devices, smxUSB has a small code and RAM requirement. For smxUSBH (Host) with mass storage driver, typical code and RAM sizes are 29KB and 6KB including the driver for the ISP1362 controller. For smxUSBD (Device) with mass storage emulation, typical code and RAM sizes are 15KB and 6KB including the driver for the ISP1181 controller. smxUSBO (OTG) adds 7KB code.

While optimally supported by SMX® RTOS, smxUSB is portable
and can be easily ported to proprietary environments, other RTOSs, and is often used standalone. Read and write performance are excellent, and are listed in the data sheets.

Available with smxUSBH or separately, are host class drivers including mass storage drive, mouse and keyboard
(HID), printer, hub, CDC ACM, and USG to serial adaptor. With smxUSBD are device class emulators for serial, mouse, mass storage, composite drivers, and Ethernet over USB (RNDIS). Device class emulators are Windows compatible and do not require custom Windows

Used with smxFS (DOS/FAT-compatible file system), smxUSBH
(Host) supports mass storage devices such as Thumb Drives and other USB drives. smxUSBD (Device) used with smxFS turns an embedded device into a Windows-compatible
USB Drive. Both solutions provide an easy way of transferring files to and from an embedded device.


Consumer and embedded devices that can benefit from USB connectivity.


  • Small code and RAM foot print.
  • Easily adapted to proprietary environments, commercial
    RTOSs, or standalone use.
  • Pre-integrated with SMX RTOS.
  • With smxFS (file system), smxUSBH enables easy Thumb Drive support.
  • smxUSBD enables easy connection to Window’s PCs without requiring custom Window’s drivers.
  • Full support for many USB host and device controllers,
    including those on popular processor chips.
  • OTG permits dynamic host or device operation.


  • Support for USB 1.1, USB 2.0 and OTG
  • Full source code in ANSI-C with 90 days of support and maintenance
  • Support for wide range of 16 and 32 bit processors: ARM, ColdFire, PowerPC, x86 and others.
  • Supplied with complete, easy-to-read manuals which include detailed sections on porting.
  • Support for wide range of SOC on-chip USB controllers,
    external USB controllers such as the NXP ISP family, and OHCI, UHCI and EHCI compliant controllers.



Contact Information

Micro Digital Inc

2900 Bristol Street
Suite G 204
Costa Mesa, CA, 92626

tele: 714.437.7333
fax: 714.432.0490

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