Design Article
Introduction to USB—Part VII
Christian Legare, Micrium
2/13/2013 12:37 PM EST
Introduction to USB--Part VII, Page 2.
1-14-1 USB DEVICE TESTING
The USB Implementer's Forum offers free diagnostic tools including the compliance test tool USB Command Verifier (USBCV).
To verify interoperability and functionality of a USB device, the USB-IF uses a USB equipment setup of known, good, USB devices. When all interconnected together it is referred to as the Gold-tree (see Figure 1-33).
The gold-tree is supposed to consist of USB-IF certified consumer devices that are widely available in the market. Unfortunately, the shelf-life of consumer products is limited and some items become difficult to find as time goes by. As a result, the USB-IF will no longer identify specific makes and models of products for the gold-tree. The shelf life and availability of consumer products is just too short and is difficult to maintain. Because there is nothing special about the peripherals and hubs, except being USB Certified, product classes and types are specified.
1-14-3 USB HOST TESTING
Unfortunately, there are no standards to test a USB host. Because the USB bus is a master/slave bus, a device can be tested with a host. but a host cannot test a host. A manufacturer wanting to validate the operation and performance of a USB host based product will have to develop his own testing methods.
If you are using a commercial USB host stack, the vendor will be able to help you with the software validation. But for the hardware validation, you are on your own when validating a USB host based product.
1-14-1 USB DEVICE TESTING
The USB Implementer's Forum offers free diagnostic tools including the compliance test tool USB Command Verifier (USBCV).
All the drivers offered by Micriμm have been tested with all the above USB-CV test suites.
To verify interoperability and functionality of a USB device, the USB-IF uses a USB equipment setup of known, good, USB devices. When all interconnected together it is referred to as the Gold-tree (see Figure 1-33).
The gold-tree is supposed to consist of USB-IF certified consumer devices that are widely available in the market. Unfortunately, the shelf-life of consumer products is limited and some items become difficult to find as time goes by. As a result, the USB-IF will no longer identify specific makes and models of products for the gold-tree. The shelf life and availability of consumer products is just too short and is difficult to maintain. Because there is nothing special about the peripherals and hubs, except being USB Certified, product classes and types are specified.
GOLD TREE COMPONENT LIST
- A Host PC with different USB controllers
- EHCI
- OHCI
- UHCI
- xHCI (USB 3.0)
- 5 HS self powered hubs
- One FS self-powered hub
- One FS keyboard/hub
- Five 5-meter USB cables
- One mouse
- Two mass storage devices
- One video camera
Additional information can be found HERE.
1-14-3 USB HOST TESTING
Unfortunately, there are no standards to test a USB host. Because the USB bus is a master/slave bus, a device can be tested with a host. but a host cannot test a host. A manufacturer wanting to validate the operation and performance of a USB host based product will have to develop his own testing methods.
If you are using a commercial USB host stack, the vendor will be able to help you with the software validation. But for the hardware validation, you are on your own when validating a USB host based product.
µC/USB Device: Universal Serial Bus Device Stack for the Renesas RX63N, Chapter 2, by Christian Legare, is excerpted with permission. The text is available at Micrium.
|
|
|
|
|
Navigate to related information