JPH11205412A - Computer system and usb controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of an USB(universal serial bus) controller by controlling the ON/OFF of the differential input buffer of the USB controller. SOLUTION: The differential input buffer 59 is constituted so as to be ON/ OFF controlled corresponding to the status of an USB port 34, and in the period of not transferring data through serial buses (D<+> and D<-> ) or the like, the power of the differential input buffer 59 is brought down and the operation is stopped. Thus, useless power consumption due to the operation of the differential input buffer 59 by noise or the like on the serial buses (D<+> and D<-> ) is reduced. Also, not only the power down control of the differential input buffer 59 is automatically performed by the port status of the USB port 34 but also the power down control of the differential input buffer 59 is performed regardless of the port status of the USB port 34 by software control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a computer system and a USB controller, and more particularly, to a computer system improved so that power consumption of the USB controller can be reduced and a USB used in the system.
Regarding the controller.

[0002]

2. Description of the Related Art In recent years, in personal computers and the like, in order to increase the degree of freedom of expandability of peripheral devices, U.S. Pat.
Support for SB (Universal Serial Bus) has begun. USB is a serial interface standard that can be commonly used for communication with various USB-compatible devices such as a keyboard, a mouse, a camera, a printer, and a modem. By using this USB, the connector prepared for each peripheral device can be
It can be integrated into a connector, which makes it possible to reduce the price of a personal computer and increase the degree of freedom of expandability.

In particular, in portable personal computers such as notebook type and sub-note type,
The use of a USB connector is very effective for miniaturization because there is a restriction on the mounting space of the connector.

[0004] The USB is a bus interface whose functions are separated into a device side and a host side, and has a mechanism in which the host manages devices. The host includes hardware called a host controller (HC) and software called host software (or a host control driver or USB driver).

The USB is a bus having a star network structure, and uses a connection function called a HUB to connect devices. The one at the top of the HUB is Ro
ot_HUB. This is often arranged in a place close to the host controller, and when the host controller is implemented as an LSI, the host controller and Ro
ot_HUB is built in the same LSI. This LSI is called a USB controller.

OHCI (Open Host Cont)
According to a USB specification such as a "roller interface", a suspend mode is defined in the USB controller to reduce its power consumption. In this suspend mode, the operation of most parts other than the part that detects the insertion and removal of the USB device from the USB connector is stopped.

[0007] The host software controls the USB port and manages data flowing on the USB serial bus. Therefore, when there is no need to exchange data on the bus, the state of the port is set to the disabled state or the suspended state. The disabled state is a state in which data cannot be transferred at all, such as immediately after power-on, immediately after connecting a device to a port, or when an error occurs. The suspended state is a state in which the host software keeps a port yield when data exchange is not required for a while after the data on the bus can be exchanged. Except when transferring a large amount of data on the bus, the amount of data exchange is small and the time in the suspended state becomes longer, and it is important to reduce the power consumption in this state.

[0008]

However, the conventional USB
In the controller, two USB serial bus (D ^+, D ^-) USB by transmitting a differential signal on
The power down control of the differential input buffer provided in the I / O buffer for exchanging data with the device is not performed. Because of this, USB
Even when no data transfer occurs on the serial bus,
The differential input buffer always operates, and there is a problem that the differential input buffer operates due to noise on the USB bus or the like, which wastes power.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and enables a differential input buffer to be turned on / off in accordance with the presence or absence of data transfer on a USB serial bus. It is an object of the present invention to provide a computer system and a USB controller that can reduce wasteful power consumption caused by the operation of the differential input buffer due to the above.

[0010]

In order to solve the above-mentioned problems, the present invention provides a USB device for controlling a USB device.
In a computer system having a controller,
A USB port to which the USB device is connected, port status monitoring means for monitoring the use state of the USB port, and the U
Power-down control means for powering down an input buffer for inputting data from the USB device via the USB port when it is detected that data transfer via the SB port is not performed. It is characterized by.

In this computer system, U
The input buffer can be turned on / off by the port status of the SB port. When it is detected that data transfer via the USB port is not performed, the input buffer is powered down. As a result, wasteful power consumption caused by the operation of the input buffer due to noise on the USB bus or the like can be reduced.

According to the present invention, the power down control of the input buffer is not only automatically performed based on the port status of the USB port, but also controlled by software, independently of the port status of the USB port. , Thereby enabling more flexible ON / OFF control of the input buffer.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a computer system according to an embodiment of the present invention. This computer system is a notebook-type or sub-notebook-type personal computer that can be driven by a battery, and includes a computer main body and an LCD panel unit that is openably and closably attached to the computer main body. This computer has a built-in battery 22 and is configured to be operable with electric power from the built-in battery 22.

Further, power can be supplied from an external power supply such as an AC commercial power supply via the AC adapter 23. When power is supplied from an external power source, the power from the external power source is used as an operating power source for the computer system. At this time, charging of the built-in battery 22 is automatically performed by the power from the external power supply. When the AC adapter 23 is removed or the breaker of the AC commercial power supply is turned off, the power from the built-in battery 22 is used as the operation power supply of the computer system.

On the system board of this computer system, three types of buses, that is, a host bus 1, a PCI bus 2, and an ISA bus 3, are provided as shown in the figure. Also, on the system board, a CPU 11, a host-PCI bridge device 12, a main memory 13, a VGA
Controller 14, video RAM (VRAM) 15, U
SB controller 16, PCI-ISA bridge device 1
7, BIOS-ROM 18, HDD 19, embedded controller (EC; Embedded Control)
er) 20, a power supply controller 21, and the like.

The CPU 11 executes a program loaded in the main memory 13 to execute operation control and data processing of the entire system. The main memory 13 is a memory device that stores an operating system, a device driver, an application program to be executed, processing data, and the like, and includes a plurality of DRAMs. The main memory 13 is connected to the host-PCI bridge device 12 via a dedicated memory bus having a 32-bit or 64-bit data bus.

The host-PCI bridge device 12 is a bridge LSI connecting the host bus (CPU bus) 1 and the PCI bus 2 and functions as one of the bus masters of the PCI bus 2. This host-PCI bridge device 12
Has a function of bidirectionally converting a bus cycle including data and addresses between the host bus 1 and the PCI bus 2 and a function of controlling access to the main memory 13 via the memory bus.

The VGA controller 14 is one of the PCI devices, and controls the LCD and the external CRT to control the VRAM.
The display data drawn in 15 is displayed on them. US
The B controller 16 is also realized as one of the PCI devices, and controls a USB device 35 connected to a USB port (USB connector) 34 provided in the computer main body. The USB controller 16 is realized by a one-chip LSI, and includes a host controller (HC) 31, a Root_HUB 32, and an I / O
The buffer 33 is built in.

[0019] I / O buffer 33, two serial bus (D ^+, D ^-) US By transmitting differential signals on
The buffer exchanges data with the B device 35 and outputs a differential signal on a serial bus (D ⁺ , D ⁻ ), and a differential buffer on the serial bus (D ⁺ , D ⁻ ). And a differential input buffer 59 which amplifies the input signal to the host controller (HC) 31 via the Root_HUB 32. Serial bus (D ^+, D ^-) status monitoring USB port 34 of the presence or absence of data transfer on the input end of the serial bus (D ^+, D ^-) of the differential input buffer 59 on use such as a signal Root
_HUB32.

The differential input buffer 59 is connected to the USB port 3
The differential input buffer 59 is configured to be turned on / off according to the status of No. 4 during a period in which data is not transferred via the serial buses (D ⁺ , D ⁻ ). It is powered down and its operation is stopped. Therefore, useless power consumption caused by the operation of the differential input buffer 59 due to noise or the like on the serial bus (D ⁺ , D ⁻ ) can be reduced. The power down control of the differential input buffer 59 is not only automatically performed based on the port status of the USB port 34, but also controlled by software regardless of the port status of the USB port 34. Control can also be performed.

The PCI-ISA bridge device 17 is a PC
This is a bridge LSI that connects the I bus 2 and the ISA bus 3. The ISA bus 3 has a BIOS-ROM 18, an HD
D19 and EC20 are connected.

The BIOS-ROM 18 has a system BIOS.
This is for storing S (Basic I / O System), and is constituted by a flash memory so that a program can be rewritten. System BI
The OS is a systematized function execution routine for accessing various hardware in the system.

The system BIOS includes an IRT routine executed when the system is powered on, and a group of BIOS drivers for controlling various hardware. Each BIOS driver includes a plurality of function execution routine groups corresponding to the functions for providing a plurality of functions for hardware control to an operating system or an application program.

The BIOS-ROM 18 also stores a system management program such as a suspend / resume routine. When the system is powered off, the suspend / resume routine saves the system status such as the status of the CPU registers and peripheral LSIs in the main memory 13 and powers off most other devices except the main memory 13 or the system. A suspend process such as saving the status and the contents of the main memory in the HDD 19 and turning off the system power is performed. Thereafter, when the system power is turned on, the suspend / resume routine is executed by the main memory 13 or the HDD 1.
9, the system state is restored.

The EC 20 is a controller for controlling the additional functions of the system. The EC 20 is a heat control function for controlling the rotation of the cooling fan according to the temperature around the CPU and the like. It has an LED / beep sound control function for notifying the user with a beep sound, a power supply sequence control function for controlling on / off of the system power supply in cooperation with the power supply controller 21, and the like.

The power supply controller 21 controls a power supply circuit to supply power to each unit in the system, and includes a one-chip microcomputer. The power supply controller 21 controls power supply / interruption in response to an on / off operation of a power switch (P-SW), an LCD panel opening / closing operation, and the like.

The operating power is supplied to the EC 20 and the power controller 21 even when the system is suspended. FIG. 2 shows a specific hardware configuration in the USB controller 16 necessary for on / off control of the differential input buffer 59.

The Root_HUB 32 is provided with a port state circuit 51 and a port monitor circuit 60. The port state circuit 51 controls the port status signal (P SUS). Port status signal (P SUS) is “L” in the initial state, and is set to “H” when the USB port 34 enters the suspend state. Whether the data transfer using the USB port 34 is being performed is determined by the port monitor circuit 6.
It is managed by the host software based on the signal from 0.

Registers 52 and 53 are USB controllers
16 is a configuration register provided in
Is configured to be accessible by the CPU 11.
You. The register 53 has the port state circuit 51
Port status signal (P SUS), regardless of
ON / OFF of the differential input buffer 59 by software
Power down control information for controlling is written.
Power down system for instructing to turn off differential input buffer 59
Control information is written to the register 53 by software
Output, the output signal (EMPD) from the register 53
Is set to “H”.

The register 52 includes a port state circuit 5
Port status signal (P SUS) difference
ON / OFF control of the dynamic input buffer 59 and the register 53
Differential input buffer 59 using power down control information of
Information for selecting one of the on / off controls
Is written by software. Port status
Signal (P SUS).
The selection information indicating on / off control is selected
Output from the register 52
(EAPD) becomes “H” and the output of the AND gate 55
From the port status signal (P SUS) is output
Which is supplied to the suspend signal (S
USP) to the I / O buffer 33.

When selection information indicating selection of on / off control of the differential input buffer 59 using the power down control information of the register 53 is written in the register 52, the output signal (EAPD) from the register 52 is output. Becomes "L" and is supplied to one input of the AND gate 55 through the inverter 54. Therefore, a signal (EMPD) is outputted from the output of the AND gate 55, and it is outputted through the OR gate 57. It is supplied to the I / O buffer 33 as a suspend signal (SUSP).

The suspend signal (SUSP) is supplied to three-state output buffers 58a and 59b in the I / O buffer 33.
And three-state output buffers 58a and 59 for controlling the operation of differential input buffer 59.
b, the OR of the transmission enable signal (TXENB) and the suspend signal (SUSP) by the OR circuit 60
3-state output buffer 58 whose logic is low active
a, 59b, and a suspend signal (SUSP) is directly sent to the control terminal of the low active differential input buffer 59.

The transmission enable signal (TXENB)
Is a signal that becomes “L” when the USB controller 16 outputs data to the USB device. Also U
SBRCV is an output signal of the differential input buffer 59,
The data input from D + and D- is transferred to Root_HUB32.
To output to the HC 31 via the.

Next, a method of automatically turning off the differential input buffer 59 using the port state of the USB port 34 will be described with reference to the timing chart of FIG.

First, "H" is set in the register 52 by software, and EAPD is set to "H". As a result, the port status signal (P SUS), the on / off control of the differential input buffer 59 is set to be valid. The host software uses the output of the port monitor circuit 60 to manage the use state of the USB port 34. When the host software detects that data transfer is not being performed, the host software controls the port state circuit 51 to suspend the USB port 34. And the output signal P SUS is set to “H”. EAPD and P SUS
And the SUSP signal becomes "H".
Since the SUSP signal is connected to the “L” active enable terminal of the differential input buffer 59, the differential input buffer 59 is turned off.

Since the signal obtained by ORing the SUSP signal and the TXENB signal is connected to the output enable terminals of the output buffers 58a and 58b, when the SUSP signal becomes "H", "H" is output to the enable terminal. Is done. Since the enable terminal is at "H", the output buffers 58a, 58 which are active when the enable terminal is at "L"
8b is also turned off.

Here, P is controlled by the host software. SUS is generated, but by using the output of the port monitor circuit 60, P automatically is generated by hardware. SUS may be generated.

Next, a method of turning off the differential input buffer 59 by software control regardless of the port status will be described with reference to the timing chart of FIG.

The software sets the register 52 to “L”,
The register 53 is set to “H”, EAPD is set to “L”,
EMPD is set to “H”. Since the EAPD outputs “L”, the AND circuit 55 outputs “L”. Also, since the EPAD is inverted and input to the AND circuit 56, the AND circuit 56 outputs "H". Since this signal is input to the OR circuit 57, the OR circuit 57 outputs "H" and the SUSP signal becomes "H". As described above, when the SUSP signal becomes “H”, the differential input buffer 59 is turned off. The SUSP signal is OR
It is logically connected to TXENB, and the OR circuit 60 outputs “H”. This output signal is connected to enable terminals of output buffers 58a and 58b that are active "L". Therefore, the output buffers 58a, 58b
Is also turned off.

Next, the software stores "L" in the register 53.
Is set to “L”, and the AND circuit 5
6 outputs "L". At this time, since the EAPD is “L”, the AND circuit 56 also outputs “L”, and the OR circuit 57
Outputs “L”. Then, the signal SUSP becomes "L", the enable terminal of the differential input buffer 59 becomes "L", and the differential input buffer 59 is turned on.

That is, the software operates in the registers 52 and 5
By setting the value to 3, the differential input buffer 59 can be controlled. FIG. 5 shows a differential input buffer 5.
Nine concrete examples are shown.

In the differential input buffer 59 of FIG. 5A, the load resistors R1 and R2 and the gate are connected to a serial bus (D
^+, D ^-) connected to the transistors Q1, Q2, and in addition from the current source I1 to the configuration of the conventional differential amplifier circuit configured, in the transistor Q3 as shown, Q4 each transistor Q1, Q2 and load resistance It is additionally connected between R1 and R2. The transistors Q3 and Q4 are provided for controlling connection / disconnection between the differential amplifier circuit and the power supply VCC terminal.
The above-mentioned suspend signal (SUSP) is inverted and supplied to the gate of Q4. When the suspend signal (SUSP) becomes "H", the transistors Q3 and Q4 are turned off, and the power supply to the differential amplifier circuit is cut off.

The transistors Q3 and Q4 may be connected between the power supply terminal and the load resistors R1 and R2. FIG.
In the differential input buffer 59 of FIG.
1, R2, gate serial bus (D ^+, D ^-) connected to the transistors Q1, Q2, and a current source I1 in addition to the configuration of the conventional differential amplifier circuit composed of, as shown transistors Q3, Q4 is the transistor Q1, Q2
The gate and the serial bus ⁽⁺ D, D ^-) is additionally connected between the. The above-mentioned suspend signal (SUSP) is inverted and supplied to the gates of the transistors Q3 and Q4. When the suspend signal (SUSP) becomes “H”,
Transistors Q3, Q4 is turned off, whereby the serial bus (D ^+, D ^-) differential amplifier circuit regardless of the signal change on will not work at all.

As described above, the control terminal for controlling the operation of the differential input buffer 59 is provided, and the differential input buffer 5 is controlled by the port status or software control.
By controlling the 9 ON / OFF, a serial bus (D ^+, D ^-) and it is possible to reduce wasteful power consumption due to noise on.

[0045]

As described in detail above, according to the present invention,
The on / off control of the differential input buffer can be controlled according to the presence / absence of data transfer on the USB serial bus.
It is possible to reduce unnecessary power consumption due to the operation of the differential input buffer due to noise on the SB bus and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a computer system according to an embodiment of the present invention.

FIG. 2 is an exemplary view showing a configuration of a USB controller provided in the system of the embodiment.

FIG. 3 is a first timing chart illustrating an on / off control operation of a differential input buffer in a USB controller provided in the system of the embodiment.

FIG. 4 is a second timing chart illustrating the on / off control operation of the differential input buffer in the USB controller provided in the system of the embodiment.

FIG. 5 is a circuit diagram showing a configuration of a differential input buffer in the USB controller provided in the system of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... CPU 13 ... Main memory 16 ... USB controller 18 ... BIOS-ROM 19 ... HDD 31 ... Host controller (HC) 32 ... Root_HUB 33 ... I / O buffer 51 ... Port state circuit 52, 53 ... Register 55, 56 ... AND Circuits 57, 60: OR circuit 58: Output buffer 59: Differential input buffer 60: Port monitor circuit

Claims (7)

[Claims] 1. A USB for controlling a USB device
In a computer system provided with a controller, a USB port to which the USB device is connected, port status monitoring means for monitoring a use state of the USB port, and data transfer via the USB port by the port status monitoring means A computer system comprising: power down control means for powering down an input buffer for inputting data from the USB device via the USB port when it is detected that the USB device has not been touched. 2. A first register configured to be accessible by a CPU of the computer system, in which control information indicating ON / OFF of the input buffer is written, and control information indicating OFF of the input buffer in the first register. 2. The computer system according to claim 1, further comprising: means for powering down the input buffer by using the power-down control means when is written. 3. The information processing apparatus according to claim 1, further comprising a selection unit that selects one of a detection result of the port status monitoring unit and control information of the first register as a factor for powering down the input buffer. And a power-down control based on port status indicating the presence or absence of data transfer via a USB port and a power-down control using software using the first register. Item 3. The computer system according to Item 2. 4. The apparatus according to claim 3, further comprising a second register configured to be accessible by a CPU of said computer system, wherein control information for controlling a selection operation by said selection means is written. Computer system. 5. The input buffer is constituted by a differential amplifier circuit, and the power of the input buffer is shut down by interrupting power supply to the differential amplifier circuit or by a differential input terminal of the differential amplifier circuit. 2. The computer system according to claim 1, wherein said computer system is electrically isolated from a serial bus transmitted from said USB port. 6. A USB for controlling a USB device
In the controller, a port status monitoring unit that monitors a use state of a USB port to which the USB device is connected; and when the port status monitoring unit detects that data transfer via the USB port is not performed, A USB controller, comprising: power-down control means for powering down an input buffer for inputting data from the USB device via the USB port. 7. A first register configured to be accessible by a CPU of a computer system provided with the USB controller, in which control information indicating ON / OFF of the input buffer is written, and wherein the input buffer is provided in the first register. Means for powering down the input buffer by using the power-down control means when the control information indicating OFF is written, and any of a detection result by the port status monitoring means and control information of the first register. Selection means for selecting one of the two as a factor for powering down the input buffer, the power supply control by port status indicating the presence or absence of data transfer via a USB port, and the first register Power down control by software using 7. The USB controller according to claim 6, wherein the USB controller is configured to be able to execute selectively.