Device and method for efficient bulk data retrieval using a universal serial bus

A system for communicating data from a USB device to a USB host over a USB bus, comprising:

• means in the device for communicating a data available signal to the host indicating that data is available to send to the host;
• means in the host for communicating data requests to the device once the data available signal is received by the host;
• means in the device for communicating the data from the device to the host in response to the data requests;
• means in the device for communicating a flag to the host when the device has not had retrievable data for a predetermined time;
• and
• means in the host for halting the data requests when the flag is received by the host.

A USB device which communicates bulk data to a USB host over the USB bus, the device comprising:

• means for generating an interrupt signal indicating that bulk data is available for communication to the USB host;
• means, in response to bulk data requests received from the host, for communication of the bulk data to the host;
• and
• means for generating a flag for a predetermined time following when no bulk data is available at the device so that the host stops sending the bulk data requests.

A USB host which retrieves bulk data from a USB device over a USB bus, the host comprising:

• means for receiving a data available signal from the device indicating that data is available to send to the host;
• means for communicating data requests to the device once the data available signal is received by the host;
• means for retrieving the bulk data from the device in response to the data available signal;
• means for receiving a flag from the device when the device has not had retrievable data for a predetermined time;
• and
• means for halting the data requests when the flag is received by the host.

A USB device for communicating data from the device to a USB host, the device having an interrupt or isochronous endpoint for communicating interrupts to the host and a bulk data endpoint for communicating bulk data to the host, the device comprising:

• means for communicating a signal over the interrupt or isochronous endpoint to the host indicating that the device has bulk data to communicate to the host;
• means for communicating bulk data over the bulk data endpoint in response to bulk data requests from the host generated based on the signal over the interrupt or isochronous endpoint;
• means for counting a predetermined period of time when the device is generating a NAK signal in response to the bulk data requests from the host because the device does not have any bulk data;
• and
• means for communicating a signal over the bulk endpoint to the host, once the predetermined period of time has elapsed, indicating that the host halts the bulk data requests until another signal over the interrupt or isochronous endpoint is received.

A USB device configured to communicate bulk data to a USB host over a USB bus, the device comprising:

• a first circuit configured to generate an interrupt signal indicating that bulk data is available for communication to the USB host;
• a second circuit configured to communicate the bulk data to the host in response to bulk data requests received from the host;
• and
• a third circuit configured to generate a flag for a predetermined time following when no bulk data is available at the device so that the host stops sending the bulk data requests.