Troubleshooting: Connection Stability Between the USB Host Client Driver and the USB Host Controller Driver
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8/28/2008
The following table shows descriptions and resolutions of problems you may encounter with the stability of your USB connection.
| Description | Resolution |
|---|---|
Power configuration requests from the USB driver may destabilize USB connections to a power-sensitive desktop computer. |
Handle only one power configuration request at a time. |
Power requests of 500 mA from the desktop computer may destabilize USB connections to a power-sensitive desktop computer. The desktop computer may not release 500 mA to the target device. 500 mA allows a battery to charge more effectively. |
Only request 100 mA from the desktop computer. In this case, many desktop computers will accommodate the request without destabilizing the USB connection. Keep in mind that battery charging is not as effective with only 100 mA. |
FIFO buffer overflows may occur if the maximum data size that can enter the USB pipe is larger than the size of the FIFO buffer. |
The maximum data size that can enter the USB pipe should not be larger than the FIFO buffer. |
Synchronization issues between the USB host and the target device. This can happen when the data toggle resets and becomes unknown to the host. For example, do not reset the data toggle during execution of the PurgeComm function in the USB driver. |
Data toggle resets on the device should only occur in response to request from the USB host. For example, when the host sends a CLEAR_FEATURE request or an ENDPOINT_HALT request. |
Note
You may want to consider turning on the device automatically when the device connects to a USB port.