Inquiring apparatus and method thereof
First Claim
1. An inquiring apparatus, provided in an electronic apparatus having a central processor unit (CPU), the electronic apparatus comprising a clock controller, and a main bus, the inquiring apparatus comprising:
- a multiplexer for selectively coupling a first bus or a second bus with the main bus,peripheral device associated with an address;
wherein when the CPU needs to wait for the peripheral device coupled to the main bus to come to an expected state, the CPU activates the inquiring apparatus to inform an awakening unit of the address of the peripheral device and to make the multiplexer couple the second bus with the main bus so that the awakening unit, instead of the CPU, repeatedly inquires the current state of the peripheral device associated with the address to determine whether the current state of the peripheral device agrees with the expected state and so that the CPU is placed into a power-saving state in which the clock controller stops outputting a clock to the CPU.
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Abstract
An inquiring apparatus and method thereof is provided for assisting the CPU to inquire the state of the peripheral device. When the CPU needs to perform an inquiring process to wait for a peripheral device to come to an expected state, an inquiring apparatus is activated, instead of the CPU, to perform an inquiring process. The CPU is placed in a power-saving state which stops outputting the clock to the CPU when the inquiring apparatus performs the inquiring process. The inquiring process includes outputting a read cycle to the peripheral device receiving a current state of the peripheral device in response to the read cycle; and comparing the current state with the expected state. If the current state and the expected state are the same, the clock is outputted to the CPU again.
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Citations
15 Claims
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1. An inquiring apparatus, provided in an electronic apparatus having a central processor unit (CPU), the electronic apparatus comprising a clock controller, and a main bus, the inquiring apparatus comprising:
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a multiplexer for selectively coupling a first bus or a second bus with the main bus, peripheral device associated with an address; wherein when the CPU needs to wait for the peripheral device coupled to the main bus to come to an expected state, the CPU activates the inquiring apparatus to inform an awakening unit of the address of the peripheral device and to make the multiplexer couple the second bus with the main bus so that the awakening unit, instead of the CPU, repeatedly inquires the current state of the peripheral device associated with the address to determine whether the current state of the peripheral device agrees with the expected state and so that the CPU is placed into a power-saving state in which the clock controller stops outputting a clock to the CPU. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An inquiring method, for assisting a CPU to repeatedly inquire a peripheral device, the method comprising steps of:
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when the CPU needs to perform an inquiring process to wait for the peripheral device to come to an expected state, activating an inquiring apparatus, instead of the CPU, to perform an inquiring process; placing the CPU in a power-saving state which stops outputting a clock to the CPU when the inquiring apparatus performs the inquiring process; wherein the inquiring process comprises; outputting a read cycle to the peripheral device to inquire a current state of the peripheral device; receiving the current state of the peripheral device in response to the read cycle; and comparing the current state with the expected state. - View Dependent Claims (8)
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9. An electronic apparatus comprising:
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a processor; a clock controller; an inquiring apparatus comprising; an awakening unit, which is activated instead of the processor to inquire a current state of a peripheral device associated with an address on a main bus when the processor activates the inquiring apparatus to inform the awakening unit of the address of the peripheral device; a multiplexer for selectively coupling one of the processor and the awakening unit to the main bus; and wherein when the processor needs to wait for a peripheral device coupled to the main bus to come to an expected state, the processor activates the inquiring apparatus to inform the awakening unit of the address of the peripheral device and to make the multiplexer couple the awakening unit to the main bus so that the awakening unit, instead of the processor, repeatedly inquires the current state of the peripheral device associated with the address to determine whether the current state of peripheral device agrees with the expected state and so that the processor is placed into a power-saving state in which the clock controller stops outputting a clock to the processor. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification