USB peripheral device storing an indication of an operating power mode when a host went into hibernate and restarting at the power mode accordingly
View Patent ↗A device capable of operating at both a low power mode and at a high power mode which is connected to a host by a USB connection. The device includes a non-volatile memory which stores the operating state of the device when the host goes into hibernate mode and a flag which indicates that the host has entered the “hibernate” mode. When the device powers up, the previous state of the device is read from the memory. If the previous state was high power and the hibernate flag is set, the device restarts in high power mode without the need of any initialization to determine if the host will allow operation at high power speed mode. The device determines that the host is going into suspend mode (rather than power down mode) by determining if a suspend signal on the USB bus is followed by a power down operation.
1. A method of operating a peripheral device connected to a host via a Universal Serial Bus (USB), said device being able to operation at either low power mode or high power mode, said method including:
detecting when the host goes into a hibernate mode, and when said host re-starts after hibernate mode,
when said host goes into hibernate mode, saving in a non-volatile memory an indication that the host went into hibernate,
when said host goes into hibernate mode, saving in non-volatile memory an indication of whether the device was operating at low power mode or high power mode when the host went into hibernate mode,
when said host restarts after going into hibernate mode, restarting said device at high power mode if said device was in high power mode when said host went into hibernate mode, and
when said host restarts after going into hibernate mode, restarting said device at low power mode if said device was in low power mode when said host went into hibernate mode.
2. The method recited in claim 1 wherein said system is operating in accordance with the MS Windows™ operating system.
3. The method recited in claim 2 wherein said MS Windows™ operating system has a hibernate mode.
4. The method recited in claim 1 wherein when said device is initially powered up, it detects if the connection is capable of handling a high speed mode, or if the device must operate at full speed.
5. The method recited in claim 1 wherein said peripheral device determines that said host is going into hibernate mode by detecting in sequence a suspend command from the host followed by a power off command.
6. The method recited in claim 1 wherein said peripheral device operates at full speed in said low power mode.
7. The method recited in claim 1 wherein said peripheral device operates at high speed in said high power mode.
8. The method recited in claim 1 wherein said system is operating in accordance with an MS Windows™ operating system and said MS windows operating system has a hibernate mode.
9. The method recited in claim 1 wherein said host issues a suspend command host followed by a power off command prior to going into hibernate mode.
10. The method recited in claim 9 wherein said peripheral device determines that said host is going into hibernate mode by detecting in sequence a suspend command followed by a power off command.
11. A peripheral device adapted for connection to a host via a Universal Serial Bus (USB), said peripheral device capable of operating at both a low power mode and a high power mode, said peripheral device including the combination of;
a non-volatile memory means for storing an indication that the host has gone into hibernate mode and an indication of the power mode at which said peripheral device was operating when said host went into hibernate mode,
means operable when said host is restarted after having gone into hibernate mode for re-starting said peripheral device in high power mode if said device was operating in high power mode before said host went into hibernate mode and for starting said peripheral device in low power mode if said device was operating in low power mode when said host went into hibernate mode.
12. The device recited in claim 11 wherein said host issues a suspend command on said USB bus is followed by a power down command prior to going into hibernate mode.
13. The device recited in claim 12 including means for determining that said host is going into hibernate mode by determining if a suspend command on said USB bus is followed by a power down command.
14. The device recited in claim 11 wherein said host is operating in accordance with the MS Windows™ operating system.
15. The device recited in claim 11 wherein said device operates at full speed in said low power mode and said device operates at high speed in said high power mode.
16. A method of operating a peripheral device connected to a host via a Universal Serial Bus (USB), said host having a hibernate mode, said peripheral device being able to operation at either low power mode or high power mode, said method including:
detecting when the host goes into a hibernate mode,
saving in a non-volatile memory an indication that the host went into hibernate,
saving in non-volatile memory an indication of whether the device was operating at low power mode or high power mode when said host went into hibernate mode,
when said host restarts after going into hibernate mode, restarting said device at high power mode if said device was in high power mode when said host went into hibernate mode, and
when said host restarts after going into hibernate mode, restarting said device at low power mode if said device was in low power mode when said host went into hibernate mode.
17. The method recited in claim 16 wherein said system is operating in accordance with the MS Windows™ operating system.
18. The method recited in claim 17 wherein said MS Windows™ operating system has a hibernate mode.
19. The method recited in claim 16 wherein said host issues a suspend command host followed by a power off command prior to going into hibernate mode.
20. The method recited in claim 19 wherein said peripheral device determines that said host is going into hibernate mode by detecting in sequence a suspend command from the host followed by a power off command.