USB 2.0 Embedded Host testing


The USB 2.0 Embedded Host is covered in the On-The-Go and Embedded Host supplement of the  USB 2.0 Spec. An Embedded host is defined as a non-PC hosts that supports a specific, targeted set of peripherals. The developer of each Targeted Host product defines the set of supported peripherals on a Targeted Peripheral List (TPL). It has one or more Standard-A or Micro-AB receptacles. Embedded Host products may also offer USB peripheral capability, delivered separately via one or more Type-B receptacles (device).  In addition it is possible for an Embedded Host to be a Charging Downstream Port (CDP) as defined in the Battery Charging Specification 1.2.
 
For the USB-IF Compliance program an Embedded Host should under go the following test:
USB 2.0 Embedded Host  High Speed Electrical Full Speed Signal Quality Low Speed Signal Quality Vbus Drop Vbus Droop Interoperability Manual Testing Battery Charging tests (CDP)
High Speed    High Speed Y Y F Y M Y F
Full Speed     Basic Speed Y F Y M Y F
Low Speed    Basic Speed Y Y M Y F

Y = Always required
F = Required if feature is supported
M = Required if there are multiple downstream ports

If the product support Battery Charging 1.2 the product must under go the Battery Charging 1.2 compliance tests

When submitting for USB-IF Compliance also take care of the following:
- Check that the product complies with the USB-IF requirements of the USB-IF Compliance website
- Complete the OTG & EH Compliance Checklists with on the last page the TPL
- Complete the System Checklist
- Make sure that the used A or micro-AB Receptacle is USB-IF certified !!! (check the Integrators List - USB-IF members only-)
- Carefully read Chapter 7 of the USB On-The-Go and Embedded Host Automated Compliance Plan 1.2 and go through all the manual test.
- Make sure that a High Speed capable embedded host must be able to enter the high speed electrical test modes via PID/VID detection. 





When completing the Checklist and TPL take the following into account: 
  • TPL must be detailed enough for example for storage:
    • Define in detail what type is supported like USB DVD/CDROM, Floppy, Pendrive, Harddrive, Flashcard reader,  how many partions are supported, what file systems (FAT32, NTFS,...), are additional interfaces supported.         
    • Make sure it's future prove there UASP is starting to come for storage.
    • Include at least one device that prove to work with it's details
  • Know the suspend/resume behavoir of the embedded host.
    • USB Suspend state is when Vbus is still 5V and D+ high and D- low and the connected device is in suspend state.
    • Take remote wakeup into acount if TPL include remote wakeup devices.
    • Include all different type of suspend that are supported.
In addition of the USB-IF Compliance program it's advisable to also perform following test.
  • Overcurrent test
  • Intens Interoperability with many different devices
  • TDR Impedance measurement
  • Real time EYE diagram
  • Testing under different temperatures conditions 
  • Test the Checklist items that are not coverd in the compliance plan
  • High Speed disconnect detect test